dane county chapter 4 risk assessment...the dane county hazard and risk analysis, an appendix to the...

CHAPTER 4 NATURAL HAZARDS RISK ASSESSMENT

Dane County 4.1 Multi-Hazard Mitigation Plan October 2009

Requirement §201.6(c)(2):

[The plan shall include] A risk assessment that provides the factual basis for activities proposed in the strategy to reduce losses from identified hazards. Local risk assessments must provide sufficient information to enable the jurisdiction to identify and prioritize appropriate mitigation actions to reduce losses from identified hazards.

As defined by the Federal Emergency Management Agency (FEMA), risk is a combination of hazard, vulnerability, and exposure. “It is the impact that a hazard would have on people, services, facilities, and structures in a community and refers to the likelihood of a hazard event resulting in an adverse condition that causes injury or damage.”

The risk assessment process identifies and profiles relevant hazards and assesses the exposure of lives, property, and infrastructure to these hazards. The process allows for a better understanding of a jurisdiction’s potential risk to natural hazards and provides a framework for developing and prioritizing mitigation actions to reduce risk from future hazard events.

This risk assessment followed the methodology described in the FEMA publication Understanding Your Risks—Identifying Hazards and Estimating Losses (FEMA 386-2, 2002), which breaks the assessment down to a four-step process:

1) Identify Hazards

2) Profile Hazard Events

3) Inventory Assets

4) Estimate Losses

Data collected through this process has been incorporated into the following sections of this chapter:

Section 4.1: Hazard Identification. Identifies the hazards which threaten the planning area and describe why some hazards have been omitted from further consideration. Discusses the research methodology utilized to gather the data in this plan.

Section 4.2: Hazard Profiles. Discusses each of the included hazards which threaten the planning area. Provides a brief definition and overview of the hazard and reviews significant previous occurrences of the hazard. Includes the following sub-sections for each hazard: description, geographic extent, previous occurrences, probability of future occurrences, exposure assessment, impact assessment, estimating potential losses and development trends assessment, and overall vulnerability summary.

Section 4.3: Vulnerability Summary. Provides a county-wide analysis of exposure to hazards. This is a general picture that assesses common exposures for all hazards and includes specific data such as demographics, property values, and critical facilities. Combines the estimation of a hazard’s occurrence probability with the associated


vulnerabilities of critical infrastructure and populations. Includes a summary of the hazard risk ratings and prioritizes hazards for mitigation implementation purposes.

Section 4.4: Mitigation Capabilities Assessment. An inventory of existing mitigation activities and existing policies, regulations, and plans that pertain to mitigation and affect the County’s net vulnerability.

4.1 Hazard Identification

Requirement §201.6(c)(2)(i): [The risk assessment shall include a] description of the type…of all natural hazards that can affect the jurisdiction.

4.1.1 Methodology

The risk assessment is the basis of the County’s hazard mitigation strategy. As used here, risk assessment means the evaluation of the impact of natural hazards on the human-built environment, businesses, social structure and services, and the natural environment. The risk assessment is essential. It allows the multi-jurisdictional participants to develop targeted mitigation strategies to reduce exposure and potential for loss, which is addressed in the next chapter.

There are various risk assessment methodologies, which differ by focus and scale. FEMA recommends an analysis focused on critical facilities and the potential for future economic losses. Other methods focus on social characteristics and the ability of society to adapt to the hazard. Scale varies from analyzing the direct impact of a single event to examining the complex interplay of events and hazards and the potential ‘ripple effects’ of hazards. Spatial scales range from the analysis of a hazard’s impact on a single, local government through analyzing county, state, or even federal-wide impacts.

The chapter identifies the hazards first. Then, the hazard profiles and vulnerability assessments are combined, and each hazard is discussed separately. A generalized risk analysis follows which interprets the general findings and includes a graphic representation. Finally, a capabilities assessment discusses the county-wide mitigation procedures and tools already in place, utilizing a multi-hazard approach. Specific jurisdictional considerations are included in the relevant jurisdictional attachments. The specific method for profiling and assessing vulnerability varies between hazards and is described in detail in each section but they all follow the same general format.

4.1.2 Potential Hazards List

The Dane County Hazard and Risk Analysis, an Appendix to the County’s Emergency Operations Plan (EOP), served as the starting point for the initial risk assessment. Based on the Hazard Analysis and input from the Citizens Advisory Committee, the planning committee considered 11 hazards for the original plan developed in 2004. The review conducted in 2008-2009 re-examined these hazards, as well as conducted additional research to identify other hazards which should be included in this document. County-wide participation from villages, towns and the City of Madison provided localized knowledge and information to update the plan. Only natural hazards are considered in this document.


Based on the recommendations by FEMA, the HMPC, and historical records for Dane county, the following hazards (listed alphabetically), were considered during the plan update:

• Dam Failure • Drought • Earthquake • Erosion • Expansive Soils • Flood • Fog

• Hailstorm • Landslides • Levee Failure • Lightning • Severe Cold • Excessive heat • Severe Thunderstorm

• Severe Winter Storm • Subsidence • Tornado • Wildfire • Windstorm


Table 4.1 Preliminary Hazard Ranking by the 2009 Hazard Mitigation Planning Committee

Impact Attributes Rating: (0-1-2-3) Hazard Attributes

Rating: (1-2-3) Primary Impact (Short Term – Life and Property)

Secondary Impact (Long Term – Community Impacts)

Hazard

Area of impact

Past history, probability of

future occurrence

Short term time factors

Impact on General

Structures

Impact on Critical

Facilities

Impact on At-Risk

PopulationsSocial Impact

Economic Impact

Severity of other

associated secondary

hazards

Total

Dam/Levee Failure 1.0 1.5 2.5 1.5 1.5 0.5 1.5 1.5 1.5 13.0

Extreme Cold 2.9 2.3 1.2 1.2 1.2 2.2 1.1 1.1 1.2 14.4 Extreme Heat 2.9 2.0 1.1 0.7 0.9 2.9 1.7 1.6 1.6 15.4 Drought 2.8 1.4 1.1 0.1 0.2 1.0 1.3 2.2 1.9 12.0 Erosion 1.5 1.5 1.5 1.0 0.5 0.0 1.0 1.0 1.0 9.0 Flood 1.7 2.1 1.9 2.1 1.6 1.4 1.8 2.1 2.1 16.8 Fog 2.1 2.2 1.8 0.0 0.1 0.2 0.3 0.4 0.8 7.9 Hail Storm 1.2 2.1 2.6 1.4 0.9 0.6 0.6 1.3 1.1 11.8 Landslide 1.0 1.0 2.0 1.0 1.0 0.0 0.0 0.0 0.0 6.0 Lightning 1.1 2.3 2.7 1.3 1.4 0.8 0.8 1.0 1.2 12.6 Tornado 1.2 2.0 2.9 2.9 2.8 2.2 2.4 2.6 2.3 21.3 Wildfire 1.1 1.4 2.2 0.4 0.4 0.9 0.8 0.9 0.7 8.8 Windstorm 2.1 2.3 2.2 1.7 1.7 1.2 1.1 1.6 1.6 15.5 Winter Storm 2.9 2.6 1.3 1.3 1.3 2.2 1.7 2.0 1.9 17.2 Land Subsidence 1.5 1.5 1.5 2.0 1.0 0.5 1.0 0.0 0.0 9.0 Elevated groundwater 3.0 3.0 2.0 2.0 2.0 1.0 1.0 1.0 1.0 16.0

Source: Data Collection Guides.


This table was distributed to the members of the initial planning committee when the Hazard Mitigation was first drafted in 2004. The committee members each completed the table using their own experiences and judgment to assign the numeric values. As part of the update process, all participating members of the HMPC were distributed blank versions of this table again. The input from Dane County government is represented above. This served as the preliminary hazard ranking process for the 2009 Update, which provided focus and scope for the hazard mitigation planning committee and the update team. According to this table, the HMPC ranked Tornado as the most dangerous and costly hazard, with Winter Storms, Floods, Elevated Groundwater Tables, Windstorms, Extreme Heat and Extreme Cold, Hail Storms, Dam Failures, Lightning, Erosion, Subsidence, Fog and Landslides following. Some hazards listed in this table were later combined/consolidated as described in the next section.

Hazard ranking worksheets for individual jurisdictions are presented in their respective annex. This table and additional hazard vulnerability tables in each annex serve the purpose of differentiating the jurisdiction’s risk from each hazard, as they vary from that of the planning area as a whole. Unique or varied risks are discussed in the annex, where applicable.

4.1.3 Hazards Not Included, Added, Modified or Combined

After conducting a cursory review of Dane County’s geographic location and climate, several of the natural hazards included in the initial composite list were discarded because they are not relevant to Dane County. These include: Avalanche, Costal Erosion, Costal Storm, Earthquake, Expansive Soils, Hurricane, Tsunami, and Volcano. Earthquake was considered during the 2009 update, but did not warrant a full hazard profile, as the probability of a damaging event is extremely low based on an analysis associated with the Wisconsin State Hazard Mitigation Plan. Severe Thunderstorm is not included because the damaging effects of such storms (hail, lightning, and high wind) are profiled as individual hazards as this better reflects the individual hazard risks and occurrences for Dane County. Levee failures were researched but there are no documented levees in Dane County, so the hazard was removed from the list. Severe Cold was expanded to include Wind-chill factors. Several new hazards were profiled for the 2009 update, including Dam Failures, Erosion, Landslides and Sinkholes, and Elevated Groundwater Tables. Elevated Groundwater Tables is profiled as part of the Flood hazard, and Landslides and Sinkholes and Erosion are addressed in a single chapter, due to their similar geologic characteristics.

4.1.4 Final Hazards List (updated 2008-2009)

As updated during the plan review conducted in 2008-2009, the final hazards which are extensively profiled, including significant vulnerability assessment, risk analysis, and impact assessments, are listed in alphabetical order:

• Dam Failure • Drought • Flood • Fog • Hailstorm • Landslide, Sinkholes and Erosion • Lightning • Severe Cold & Wind-chill • Excessive heat


• Severe Winter Storm • Tornado • Wildfire • Windstorms

4.1.5 Disaster Declaration History

As part of the hazard identification process, the HMPC researched past events which triggered federal and/or state emergency or disaster declarations in the planning area. Federal and/or state disaster declarations may be granted when the severity and magnitude of an event surpasses the ability of the local government to respond and recover. Disaster assistance is supplemental and sequential. When the local government’s capacity has been surpassed, a state disaster declaration may be issued, allowing for the provision of state assistance. Should the disaster be so severe that both the local and state governments’ capacities are exceeded, a federal emergency or disaster declaration may be issued allowing for the provision of federal assistance. There have been 16 disaster or emergency declarations in Dane County since 1971.1 Table 4.2 details these disasters.

Table 4.2 Disaster Declarations for Dane County 1971-2008

Year Disaster Type Declaration Type Damage Assessment 1976 Ice Storm Presidential Disaster $1.22 Million (Public Assistance)

1976 Drought Presidential Emergency $625 Million (statewide)

1978 Flooding and Tornados Presidential Disaster $180,000 (Public Assistance)

1984 Tornados Presidential Disaster $775,394 (Public Assistance) $11,168,220 (Individual Assistance) Dane and Iowa Counties combined

1990 Flooding and Tornados Presidential Disaster $37,000 (Public Assistance) $30,343 (Individual Assistance)

1991 Severe Storms (Windstorm) Presidential Disaster $1.33 Million (Public Assistance)

1992 Tornados Presidential Disaster $163,000 (Public Assistance)

1993 Flooding Presidential Disaster $888,000 (Public Assistance) $1,439,332 (Individual Assistance) $22.6 Million (Total Damages)

1996 Flooding and Severe Storms Local Sources $940,000 (Public Assistance) $1,2248,684 (Individual Assistance) $3.3 Million (Total Damages)

1998 High Winds and Severe Storms Local Sources $586,000 (Public Assistance)

2000 Severe Storms (Windstorm) and Flooding Presidential Disaster

$940,000 (Public Assistance) $1,248,684 (Individual Assistance) $9.3 Million (Total Damages)

2000 Snow Emergency Presidential Emergency $586,000 (Public Assistance)

2004 Severe Storms and Tornados Presidential Disaster $1.5 Million (Public Assistance)

2005 Stoughton Tornado State Disaster Fund $35 Million (Public Assistance)

2007 Flooding Presidential Disaster FEMA PDA- $3,294,210 Private $1,643,101 Public 758 homes impacted

1 Wisconsin Emergency Management “County Disasters since 1971.” Available online at http://emergencymanagement.wi.gov/sublink.asp?linksubcat2id=38&linksubcatid=87&linkcatid=40&linkid=30&locid=18 last accessed February 11, 2009.


Year Disaster Type Declaration Type Damage Assessment 2008 Snow Emergency Presidential Emergency $1,439,206 (Public Assistance)

2008 Severe Storms, Tornados and Flooding Presidential Disaster

$1,533,659 (Public Assistance) $1.76 Million (Individual Assistance) $1.64 Million (Housing Assistance) $120k other needs, 1,635 households requested aid Total damages $35,789,723

Source: Wisconsin Emergency Management and FEMA Major Disaster Declarations Website

In addition to property losses, there is potential for death or injury from many of the natural hazards that threaten the County. Figure 4.1 depicts the total number of tornados, floods, hail, lightning events and thunderstorm-force winds in Wisconsin from 1982 to 2008. The map shows the events by county and also denotes the number of directly related deaths and injuries to these severe weather events. Dane County has more documented severe weather events than any other county in Wisconsin, with nearly 200 more events than the next closest county. Though Dane County has not experienced as many fatalities directly related to these severe hazards, the numbers indicate that the potential for greater loss of life exists. Dane County does have one of the highest injury rates, which is a likely corollary to a high event occurrence and a high population count. Table 4.3 and Table 4.4 also depict weather-related deaths and injuries, but include additional information regarding heat wave, winter storm, and cold wave-related death and injury. Clearly, natural hazards present a significant threat to the population of Dane County. The past and potential impacts for each of the identified hazards are described in greater detail in each specific hazard profile.


Figure 4.1 Total Severe Weather Events in Wisconsin (1982-2008)

Source: National Weather Service


Table 4.3 Wisconsin Weather Related Fatalities (1988-2008)

YEAR Tornado Wind Hail Flooding Lightning Heat Waves Winter Storms Cold Wave

1988 0 0 0 0 4 1/0 0 0

1989 0 1 0 0 0 0 0 0

1990 0 1 0 0 1 0 0 0

1991 1 1 0 0 1 0 2 0

1992 1 0 0 0 0 0 0 0

1993 0 1 0 1 1 2 0 0

1994 4 0 0 2 0 0 0 0

1995 0 0 0 0 2 82/72 0 3

1996 1 1 0 0 0 0 0 10

1997 2 3 0 0 3 1/0 0 1

1998 0 7 0 2 0 0 0 0

1999 0 2 0 0 1 13/8 1 0

2000 0 0 0 1 2 0 0 0

2001 2 0 0 0 1 10/5 0 0

2002 0 1 0 0 1 3/5 0 0

2003 0 0 0 0 0 0/4 0 0

2004 1 1 0 1 0 0/0 0 0

2005 1 1 0 0 0 0/0 0 0

2006 0 1 0 0 1 3/1 0 0

2007 0 0 0 0 1 0/0 0 0

2008 0 0 0 1 1 0/0 0 4

Total 29 25 0 9 24 116/95 4 31 Note: Deaths listed above are “direct” deaths, in which the weather hazard is the major cause of death. However, for heat waves, the heat and humidity are sometimes labeled as “secondary” or “contributing” causes of death. These are indirect deaths, which if shown, is the second number in the heat wave column. Likewise, nearly all deaths attributed to vehicle deaths on highways in Winter Storms are “indirect” deaths, since the driver was driving too fast for the conditions, etc. In other words, the snow or ice did not kill the individual; the death was the result of a vehicle accident.



Table 4.4 Wisconsin Weather-Related Injuries (1988-2008)

Year Tornado Wind Hail Flooding Lightning Heat Waves

Winter Storms

Cold Waves

1988 4 6 0 0 7 - 0 0

1989 4 11 0 0 10 - 0 0

1990 2 2 0 0 13 - 0 0

1991 6 4 0 0 9 - 0 0

1992 61 3 0 0 3 - 0 0

1993 0 0 0 0 10 - 0 0

1994 55 5 0 0 8 - 0 0

1995 1 32 0 3 9 - 1 21

1996 13 9 0 2 7 - 3 28

1997 2 29 0 0 7 - 0 3

1998 29 70 2 5 1 - 14 0

1999 3 10 0 1 15 - 31 0

2000 16 6 38 5 6 - 0 0

2001 17 8 0 0 7 - 0 0

2002 30 2 0 1 4 - 0 0

2003 1 1 0 0 12 - 0 0

2004 17 6 0 0 1 - 0 0

2005 27 2 0 0 11 - 0 0

2006 1 2 0 0 9 - 0 0

2007 4 1 1 0 0 - 0 0

2008 20 9 0 0 2 - 0 0

Total 656 357 42 17 186 - 49 52 Note: All the injuries listed above are “direct” injuries, in which the weather hazard is the major cause of injury. Heat Wave injuries are considered “illnesses.” And are not are not tabulated above. Likewise, nearly all injuries attributed to vehicle injuries on highways in Winter Storms are “indirect” injuries, since the driver was driving too fast for the conditions, etc. In other words, the snow or ice did not injure the individual; the injury was the result of a vehicle accident. Source: National Weather Service


4.2 Hazard Profiles

The hazards identified in Section 4.1.4 Final Hazards List (updated 2008-2009) are profiled individually in this section. Much of the profile information came from the same sources used to identify the hazards during the initial planning effort in 2003. The information was reviewed for accuracy and applicability and updated where required. Significant occurrences of hazards that have occurred since the original plan’s adoption in 2004 are also included in the updated hazard profiles.

4.2.1 Profile Methodology

Each hazard is profiled in a similar format that is described below. This approach helps create a uniform planning basis and enables comparisons between the hazards. The basic outline is:

Hazard Profile

This provides the basic information for the hazard. For organizational purposes, this information is divided into the following subsections. This section fulfills Sections 5 and 6 of the FEMA Local Mitigation Plan Review Crosswalk.

Description: This subsection gives a generic description of the hazard and associated problems, followed by details on the hazard specific to Dane County.

Geographic Extent: This subsection discusses which areas of the County are most likely to be affected by a hazard event at any given time:

• Isolated: Single site occurrences for each incident • Limited: Less than 10 percent of the planning area • Significant: 10 to 50 percent of the planning area • Extensive: 50 to 100 percent of the planning area

Requirement §201.6(c)(2)(i): [The risk assessment shall include a] A description of thetype, location, and extent of all natural hazards that can affect the jurisdiction. The planshall include information on previous occurrences of hazard events[.]

Requirement §201.6(c)(2)(ii): [The plan shall also include] A description of thejurisdiction's vulnerability to the hazards described in paragraph (c)(2)(i) of this section.This description shall include an overall summary of each hazard and its impact on thecommunity. All plans approved after October 1, 2008 must also address NFIP insuredstructures that have been repetitively damaged by floods.

(A) The types and numbers of existing and future buildings, infrastructure, and criticalfacilities located in the identified hazard areas;

(B) An estimate of the potential dollar losses to vulnerable structures identified inparagraph (c)(2)(i)(A) of this section and a description of the methodology used toprepare the estimate;

(C) Providing a general description of land uses and development trends within thecommunity so that mitigation options can be considered in future land use decisions.


Previous Occurrences: This subsection contains information on historic incidents, including impacts where known. The extent or location of the hazard within or near the Dane County planning area is also included here. Information provided by the HMPC is included here along with information from other data sources. Citations are provided as footnotes.

Probability of Future Occurrences: The frequency of past events is used here to gauge the likelihood of future occurrences. Based on historical data, the likelihood of future occurrences is categorized into one of the following classifications:

• Unlikely: Between .1 and 1 percent chance of occurrence in the next 100 years, or has a recurrence interval of greater than every 100 years.

• Occasional: Between 1 and 10 percent chance of occurrence in the next year, or has a recurrence interval of 11 to 100 years

• Likely: Between 10 and 100 percent chance of occurrence in the next year, or has a recurrence interval of 10 years or less

• Highly Likely: Near 100 percent chance of occurrence in the next year, or happens yearly.

The frequency, or chance of occurrence, was calculated where possible based on existing data. Frequency was determined by dividing the number of events observed by the number of years and multiplying by 100. This gives the percent chance of event happening in any given year. Where this data results in a percent above 100 percent, the hazard is assumed to have a yearly frequency rating. Example: Three droughts over a 30-year period equates to 10 percent chance that the hazard will occur in a given year, and is then rated as “likely”.

Impact Assessment

This examines the potential impacts of the hazard on Dane County using qualitative assessment methods. Based on past experiences in Dane County, in the State of Wisconsin, and nationwide, this is a qualitative discussion of the consequences that could be expected in the aftermath of each of the hazard events. The section fulfills Sections 7, 8, and 9 Element A of the FEMA Local Mitigation Plan Review Crosswalk. Impacts are divided into two categories:

Direct Impacts

This describes the short-term consequences to people and property which occur directly as a result from the hazard.

Indirect Impacts

This describes the short-term and long-term consequences, including social and economic impacts. Secondary hazards are also examined here. Because indirect impacts are much broader and difficult to quantify than direct impacts, the section is abbreviated where appropriate to maintain mitigation focus.

Impact Magnitude and Severity Summary

This subsection summarizes the qualitative magnitude and severity of a hazard based on previous occurrences and the potential direct and indirect impacts. For most hazards the impacts are based on the event of record, or estimated worst case if history of events is limited. Impact magnitude and severity are classified in the following manner:


• Minor: Less than 5 percent of property is severely damaged; facilities and services are inoperable or closed for less than 24 hours. Minor agricultural losses. No fatalities and injuries/illnesses are treatable with first aid

• Moderate: 5 to10 percent of property severely damaged, and/or facilities are inoperable or closed for more than a week. 5-10 percent agricultural losses. Fatalities possible but most injuries/illnesses are treatable and do not result in permanent disability. Minor indirect impacts.

• Critical: 10 to 25 percent of property severely damaged, and/or facilities are inoperable or closed for at least two weeks. 10-50 percent agricultural losses. Injuries and/or illnesses result in permanent disability and some fatalities. Moderate indirect impacts.

• Catastrophic: More than 25 percent of property severely damaged, and/or facilities are inoperable or closed for more than 30 days. More than 50 percent agricultural losses. Multiple fatalities and injuries. Critical indirect impacts.

Vulnerability Assessment

This section provides an analysis of the exposed properties, people and resources in the county specific to the hazard. This section fulfills Sections 7, 8, and 9 Element A of the FEMA Local Mitigation Plan Review Crosswalk. For clarification and ease of mitigation planning, exposures are broken into four major categories:

• Population • General Property • Essential Infrastructure, Facilities, and Other Important Community Assets • Natural, Historic and Cultural Resources

These assessments draw on the countywide data collected in Section 4.3 Vulnerability Summary.

Estimating Potential Losses and Development Trends Assessment

This section provides an estimate of the potential losses to the county, and assesses the impact of development trends on future losses. The section fulfills Section 9 Element B and Section 10 of the FEMA Local Mitigation Plan Review Crosswalk.

Estimating Potential Losses

Potential losses are determined based on available data, so the methodology varies by hazard. For some hazards this may be based on average annualized losses, or using the documented event of record for the hazard and identifying the corresponding damage in dollars, adjusting them for inflation to reflect 2008 costs. Where the hazard occurs in a specific area, such as flood, GIS methods were used estimate losses to structures and critical facilities, as available data permitted.

Development Trends Assessment

This sub-section examines projected growth trends, based on recent census estimates and development trends as indicated in the most current version of the comprehensive plan. This growth potential is compared against the existing hazard data to estimate how much additional damage the county may expect if growth patterns continue.


Overall Risk Summary

Overall vulnerability for the hazard is measured in terms of geographic extent, impacts, magnitude and severity, probability of occurrence, and exposure. These findings are summarized in this section and analyzed to reveal an overall risk rating for the hazard. This rating is calculated by averaging the numeric ratings for each measurement and then assigning a corresponding interpretation to the average. This determines the vulnerability of the County to the hazard, relative to the other hazards profiled. This corresponds to Section 7 Element A of the FEMA Local Mitigation Plan Review Crosswalk. The interpretive ratings are as follows

• Low: Minor risk (0 to 1.9 average) • Medium: Moderate risk (2.0 to 2.9 average) • High: High risk. (3.0 or higher average)

4.2.2 Dam Failure

Description2

A dam is a barrier constructed across a watercourse in order to store, control, or divert water. Dams are usually constructed of earth, rock, concrete, or mine tailings. The water impounded behind a dam is referred to as the reservoir and is measured in acre-feet, with one acre-foot being the volume of water that covers one acre of land to a depth of one foot. Due to topography, even a small dam may have a reservoir containing many acre-feet of water. Dams serve many purposes, including agricultural uses; providing recreation areas; electrical power generation; and erosion, water level, and flood control.

A dam failure is the collapse, breach, or other failure of a dam that causes downstream flooding. Dam failures may result from natural events, human-caused events, or a combination thereof. Due to the lack of advance warning, failures resulting from natural events, such as hurricanes, earthquakes, or landslides, may be particularly severe. Prolonged rainfall that produces flooding is the most common cause of dam failure.

Dam failures usually occur when the spillway capacity is inadequate and water overtops the dam or when internal erosion through the dam foundation occurs (also known as piping). If internal erosion or overtopping cause a full structural breach, a high-velocity, debris-laden wall of water is released and rushes downstream, damaging or destroying whatever is in its path. Dam failures may result from one or more of the following:

• Prolonged periods of rainfall and flooding (the cause of most failures) • Inadequate spillway capacity which causes excess overtopping flows • Internal erosion due to embankment or foundation leakage or piping • Improper maintenance • Improper design • Negligent operation • Failure of upstream dams • Landslides into reservoirs • High winds (leading to wave erosion).

2 Wisconsin Emergency Management “State Hazard Mitigation Plan 2008”. Available online at ftp://doaftp04.doa.state.wi.us/wem/Hazard_Mitigation_Plan/Index.htm last accessed February 27, 2009.


For emergency planning purposes, dam failures are categorized as either rainy day or sunny day failures. Rainy day failures involve periods of excessive precipitation leading to an unusually high runoff. This high runoff increases the reservoir of the dam and, if not controlled, the overtopping of the dam or excessive water pressure can lead to dam failure. Normal storm events can also lead to rainy day failures if water outlets are plugged with debris or otherwise made inoperable. Sunny day failures occur due to poor dam maintenance, damage/obstruction of outlet systems, or vandalism. This is the worst type of failure and can be catastrophic because the breach is unexpected and there may be insufficient time to properly warn downstream residents.

The Wisconsin Department of Natural Resources (DNR) assigns hazard ratings to large dams within the State. Two factors are considered when assigning hazard ratings: existing land use and land use controls (zoning) downstream of the dam. Dams are classified in three categories that identify the potential hazard to life and property:

• High hazard indicates that a failure would most probably result in the loss of life • Significant hazard indicates a failure could result in appreciable property damage • Low hazard exists where failure would result in only minimal property damage and loss

of life is unlikely.

Wisconsin has approximately 3,800 dams, many of which were constructed before 1900. Some dams originally used for logging or milling operations are no longer used for their original purpose. An additional 700 dams were built but have subsequently washed out and no longer exist. Approximately 100 dams have been removed since 1967. The Federal Government has jurisdiction over large dams that produce hydroelectricity (approximately 5 percent of the dams in Wisconsin). Private individuals or former companies own approximately 60 percent of the dams in Wisconsin. The State owns 9 percent, municipalities such as townships or county governments own 17 percent, and 14 percent are owned by various other groups. A dam with a structural height of over 6 feet and impounding 50 acre-feet or more, or having a structural height of 25 feet or more and impounding more than 15 acre-feet, is classified as a large dam. There are approximately 1,160 large dams in the State of Wisconsin.

The Wisconsin Department of Natural Resources regulates all dams on waterways to some degree. However, the majority of dams in Wisconsin are small and not stringently regulated for safety purposes. Figure 4.2 shows the dams in and around Dane County. Dane County has 50 regulated dams. Those that have an estimated hazard class rating of high or significant are represented in Table 4.5. Stewart Lake Dam is rated as a high hazard dam and Dunkirk Millpond is rated as a significant hazard dam, while two others are rated as low hazard. According to the HMPC, Stewart Lake has had some mitigation recently that should reduce its hazard classification. An additional two dams are estimated to be high hazard, and four are classified as significant hazard dams. The Prairie du Sac dam located just outside the northwest corner of the County could potentially have a large impact in Dane County if a failure were to occur. Figure 4.2 shows the extent of inundation from a “sunny day” failure of this dam, which is also similar in extent to the 100 year floodplain on the Wisconsin River in this area of the County. The County has Emergency Action Plans for this dam as well as Stewart Lake, Babcock and Tenney Park Lock and Dam. One of the issues discovered during the planning process is the high number of dams with an ‘estimated’ or ‘unknown’ hazard class. Additional research is needed in this regard.


Table 4.5 Dams in or Affecting Dane County

Dam Name/Impound

Estimated Hazard Rating

Hazard Rating

Max Storage(acre ft)

Height (ft) Owner City

Owner Organization Stream

Mt Horeb Dam/ Stewart Lake High* High* 90 33.5 Dane County Dane County Moen Creek Stoughton Dam/ Stoughton Millpond High - 500 11 Stoughton

City of Stoughton Yahara River

Mazomanie Dam High - 100 14 Mazomanie Village of Mazomanie

Black Earth Creek

Prairie Du Sac Dam/ Lake Wisconsin High - 193,200 50 Prairie Du Sac

Alliant Power Corporation

Wisconsin River

Dunkirk Dam/ Dunkirk Millpond Significant Significant 260 20 Stoughton

Dunkirk Dam Lake District Yahara River

Marshall Dam/ Marshall Millpond Significant - 1100 15 Marshall

Blaschka and Son Milling

Maunesha River

Rockdale Dam/ Rockdale Millpond Significant - 590 14 Cambridge -

Koshkonong River

Tenney Park Lock Dam/Lake Mendota Significant - 160,000 16 Dane County Dane County Yahara River

Source: Wisconsin Department of Natural Resources; *Recently mitigated, designation may change.

Geographic Extent

Based on the location and hazard ratings of regulated dams in Dane County, the potentially impacted area due to a dam failure is less than 50 percent of the total area of the County, but it is probably more than 10 percent. Therefore, the geographic extent rating is significant.

Previous Occurrences

There are no documented occurrences of dam failures in Dane County. However, in June of 2008, Lake Delton in neighboring Sauk County overflowed, destroying four homes in the process.


Figure 4.2 Dams in and Around Dane County


Probability of Future Occurrences

It is difficult to calculate a probability for dam failures because there are no documented occurrences of past events in Dane County, though the potential does exist. Due to the 2008 failure of Lake Delton in neighboring Sauk County the chance of occurrence is assigned an occasional rating (Between 1 and 10 percent chance of occurrence in the next year, or has a recurrence interval of 11 to 100 years).

Impact Assessment

Direct Impacts

Direct impacts are rated based on the actual affect of a dam failure on the category being evaluated. Dam failures can result in extensive downstream impacts, similar to floods, but typically are more devastating due to the high velocities often associated with the events. Populations can be more severely impacted if there is not adequate warning and evacuation time.

Indirect Impacts

Indirect impacts examine those costs which are associated with, but not directly caused by, dam failures. For example, the evacuation of nursing homes which are affected by a power outage caused by the failure of a hydroelectric dam, is considered an indirect impact. Since very little data is collected on these indirect impacts it is difficult to make a statistical estimation of severity.


Without previous data to assess damages and losses or dam failure inundation maps, it is difficult to predict the magnitude and severity of this hazard on the County. However, because there are seven dams rated or estimated to be significant and high hazard dams within the County, and an additional neighboring dam that is rated as a high hazard, a magnitude severity rating of moderate is assigned.


Population

Based on current data and current dam hazard classifications in Dane County, there is limited data on which to assess the populations vulnerable to dam failures. Overall, the vulnerability of populations is estimated to be low. Approximately 70 residential parcels may be vulnerable to failure on the Prairie Du Sac Dam. Using the average household size for Dane County, an estimated 170 persons could be vulnerable to failure of this dam. An inundation mapping and analysis study of Tenny Park Dam was underway at the time of this plan’s writing, but the results were not available.

General Property

Based on the limited number of high and significant hazard dams the overall vulnerability rating on general property is estimated to be moderate. Approximately 70 residential parcels may be impacted by Prairie Du Sac Dam.


Essential Infrastructure, Facilities, and Other Important Community Assets

There is one airport and a facility with hazardous materials in the Prairie Du Sac 100-year and 500-year flood hazard zone that could potentially be impacted by a dam failure. The overall impact on essential infrastructure is low.

Natural, Historic and Cultural Resources

Based on current data and current dam hazard classifications in Dane County, there are no anticipated vulnerable natural, historic or cultural resources. The overall impact of the event on these resources is low.


Potential Loss Estimates

Without GIS-based dam failure inundation maps, quantifiable potential loss estimates are difficult to ascertain. There is one high-hazard dam that drains into Dane County - Prairie Du Sac - that has a mapped flood hazard (based on DFIRM mapping) below it on the Wisconsin River. Assuming the inundation zone would be similar to the 500-year flood, an estimated 364 developed parcels could be impacted. The total improved value is $15,441,400. Assuming 50 percent additional value for contents, the total value of property at risk equals $23,162,100. Many of these parcels are manufactured homes, which would be vulnerable to high velocity flows from a dam failure event, so losses could be as high as 100 percent of this value. The majority of these impacts would be to the Town of Mazomanie (not a participant), and some to the Town of Roxbury.

Development Trends

Hazard classifications for dams may change if new development near the dam could place people or structures at risk in the event of a failure. Development below the existing low hazard dams in the County should be carefully considered. There are no trends that indicate that this development is occurring.


Dam failures present a low risk for Dane County. The events occur infrequently, and the number of known high and significant hazard dams is low; one high hazard dam has recently been decommissioned. The ability to quantify dam failure impacts is difficult without further dam inundation studies and risk analyses. A number of dams within the County need to be assessed for their hazard rating. Depending on these future assessments, the rating for this hazard could increase in the future. Table 4.6 provides the summary for how all aspects of the hazard profile were evaluated to establish an overall hazard rating. This overall rating is compared to the other hazards in Section 4.3 Risk Analysis Summary.


Table 4.6. Overall Risk for Dam Failure

Measurement Rating Value

Geographic Extent Significant 3

Probability of Future Occurrence Unlikely 1

Vulnerability Assessment Low 1

Impact Magnitude and Severity Moderate 2

Overall Risk Rating Low 1.75

4.2.3 Drought

Description

There are a number of different ways to define drought. Generally, drought is a water shortage caused by a reduction in the amount of precipitation received over an extended period of time, usually a season or more in length. This deficiency results in a water shortage for some activity, group, agricultural or environmental sector.

The effects of a drought are aggravated by other factors such as high temperatures, high winds or low relative humidity. The severity of the impact of a drought depends on the duration, intensity, and geographic extent of the event, plus the regional demands on the water supply driven by human activities.

Drought is one of the most complex natural hazards because it is not a distinct event with a clearly defined beginning or end. It differs from other natural hazards in that it has an unusually slow onset, may affect multiple jurisdictions or counties simultaneously, and typically causes no structural damage. The effects impact various sectors in different ways and with varying intensity.

Categories of Drought

Droughts are categorized into four groups based on the severity and impact of the occurrence and measured by the industries affected. These categories are meteorological, hydrological, agricultural, and socioeconomic. It is possible for these conditions to exist simultaneously.

A Meteorological drought is the traditional conceptualization of a drought, and is defined solely on the basis of the degree of dryness. This is expressed as a relationship between actual precipitation and the expected average or normal amount, using a monthly, seasonal, or annual time scale. A meteorological drought considers only the physical attributes of the event and not the impact on social or environmental systems. 3

Hydrological droughts examine the effects of precipitation shortfalls (including snowfall) on surface or subsurface water supply (e.g., stream flow, reservoir and lake levels, ground water). The frequency and severity of hydrological drought is often defined on a watershed or river basin scale. Hydrologists examine how these events impact the entire hydrologic

3 National Drought Mitigation Center, “What is Drought? Understanding and Defining Drought” updated 2006. Available online at http://drought.unl.edu/whatis/concept.htm. Last accessed January 8, 2009.


system. Hydrological droughts are usually out of phase with or lag behind the occurrence of meteorological and agricultural droughts. It takes longer for precipitation deficiencies to appear in components of the hydrological system such as soil moisture, stream flow, and ground water and reservoir levels than in other systems. As a result, the impacts of a hydrological drought are also out of phase with drought measurements in other economic sectors. For example, a precipitation deficiency may result in a rapid depletion of soil moisture that is almost immediately discernible to agriculturalists, but the impact of this deficiency on lake and stream levels may not affect fisheries or recreational uses for many months.4

Agricultural drought links various characteristics of meteorological and or hydrological drought to agricultural impacts. This view of drought focuses on precipitation shortages, differences between actual and potential evapotranspiration, soil water deficits, reduced groundwater or reservoir levels, and the relative effects on agricultural production. Since plant water demand depends on prevailing weather conditions, biological characteristics of the specific plant, its stage of growth, and the physical and biological properties of the soil, agricultural drought accounts for the variable susceptibility of crops during different stages of crop development from emergence to maturity.5

Socioeconomic definitions of drought associate the supply and demand of economic goods with elements of meteorological, hydrological, and agricultural drought. The supply of many economic goods such as water, forage, food grains, fish, and hydroelectric power depend on weather conditions. The natural variability of climate means that water supply is ample in some years but insufficient for human and environmental needs in other years. Socioeconomic drought occurs when the demand for an economic good exceeds supply as a result of a weather-related shortfall in water supply.6

Measuring Drought

There are numerous ways to measure the meteorological intensity of drought. Examples of some of the more common indices include percent of normal precipitation, the Palmer Drought Index (PDI), the Standardized Precipitation Index (SPI), and the Surface Water Supply Index (SWSI). For the purposes of this plan, The Palmer Index is used because it is the most effective in determining long-term drought (a matter of several months) and is commonly used by the Federal Governments when measuring drought and determining drought-based aid eligibility. The Palmer Index is a measurement only of meteorological drought.

The Palmer Drought Index uses temperature and rainfall information to determine dryness or wetness over a period of time. The index is based on the supply-and-demand concept of the water balance equation, which takes into account not only the precipitation deficit at a specific location, but the water content of the soil as well. The values generated for the Palmer Index generally range from –6.0 to +6.0, with negative values indicating drier conditions and positive values indicating wetter conditions. A value range of -/+0.5 indicates “normal” conditions, while values greater than +4.0 or –4.0 indicate periods of extreme wetness or extreme drought, respectively.

The advantage of the Palmer Index is that it is standardized to local climate, so it can be applied to any part of the country to demonstrate relative drought or rainfall conditions.

4 Ibid. 5 Ibid. 6 National Drought Mitigation Center, “What is Drought? Understanding and Defining Drought”.


The limitation is that it is not useful for short-term forecasts, and is not particularly useful in calculating supplies of water locked up in snow.7

Geographic Extent

Drought is a regional phenomenon and affects the entirety of Dane County relatively simultaneously. The geographic extent rating is considered extensive.


Figure 4.3 shows the average Palmer Index values from 1985 to 2002. Dane County has experienced Palmer Index values that would indicate extreme drought five times: 1930, 1933, 1938, 1962, and 1976. This graph takes into consideration all months of the year. Because agricultural drought is a major concern in Dane County, average Palmer Index values are also represented for the growing season in Dane County (May-September) in Figure 4.4. Generally, Wisconsin experiences low quantities of precipitation accumulation in the winter months. This alone is not a problem, because demand for water is lowest during this time. However, drought in the summer months can cause financial loss or ruin for the agricultural and recreational sectors as the demand for water increases and the shortfalls become apparent.

Figure 4.3 Average Palmer Index for Dane County

7 National Drought Mitigation Center, “What is Drought? Drought Indices” updated 2006. Available online at http://drought.unl.edu/whatis/indices.htm. Last accessed January 8, 2009.


Source: Midwest Regional Climate Center, University of Illinois

The Hazard Analysis for the State of Wisconsin developed by Wisconsin Emergency Management in 2002 describes the occurrence and impact of drought on the state level. This plan relies heavily on state level data regarding past events and the following description is taken directly from the state hazard analysis:

“Droughts, both agricultural and hydrologic, are relatively common in the state. Small droughts of shortened duration have occurred at an interval of about every ten years since the 1930's. Extended, widespread droughts have been infrequent in Wisconsin. The five most significant droughts, in terms of severity and duration, are: 1987-1988, 1976-1977, 1955-1959, 1948-1950 and 1929-1934.”8

These droughts, along with the more recent occurrences in 2002-2003 and stretching over the summer of 2005, are profiled below. The selections are drawn from the National Climatic Data Center (NCDC) database. In more recent years, the NCDC has been tracking drought conditions and their consequences in greater detail. Where possible, these accounts are edited and annotated to reflect primarily Dane County information.9

Figure 4.4 Average Palmer Index for Dane County: Growing Season

-6.00

-4.00

-2.00

0.00

2.00

4.00

6.00

8.00

1895

1898

1901

1904

1907

1910

1913

1916

1919

1922

1925

1928

1931

1934

1937

1940

1943

1946

1949

1952

1955

1958

1961

1964

1967

1970

1973

1976

1979

1982

1985

1988

1991

1994

1997

2000

Years

Palm

er In

dex

Valu

e

Source: Midwest Regional Climate Center, University of Illinois

8 Wisconsin Emergency Management, Hazard Analysis for the State of Wisconsin, November 2002, p 17. 9 National Climactic Data Center, “Storm Events”, limited to Dane County, Wisconsin. Available online at http://www4.ncdc.noaa.gov/cgi-win/wwcgi.dll?wwevent~storms, last accessed January 8, 2009.


1929-1934

The 1929-1934 drought was probably the most significant in Wisconsin history considering both the event’s duration and severity. This drought had at least a 75-year recurrence interval in most of the State and over 100-year recurrence interval in certain areas. The austere economic aspects of the Depression compounded its effects. The drought continued with somewhat decreased effect until the early 1940s in some parts of the state.

1948-1950

The drought that occurred during 1948-1950 was most significant in the northern part of the state. In the most severely affected areas, the drought had a recurrence interval of greater than 70 years.

1955-1959

The drought of 1955-1959 had a recurrence interval of between 30 and 70 years in all but the northwestern corner of Wisconsin.

1963-1964

The 1963-64 drought looks like it had its start in 1962 when Dance County received only 21.63 inches of rain at Truax Field. 1963 had 26.19 inches and 1964 had 23.62 inches of rain. Normal yearly precipitation for 1869-2008 is 31.67 inches.

1976-1977

The drought of 1976-1977 was most severe in a wide band stretching from north to south across the state. Stream flow measuring stations recorded recurrence intervals from 10 to 30 years. Agricultural losses during this drought were estimated at $624 million. Sixty-four counties were declared federal drought areas and deemed eligible for assistance under the Disaster Relief Act. Additionally, numerous private and municipal wells went dry. Federal assistance was used to help communities drill new wells and obtain new water supplies.

1987-1988

Some believe the drought of 1987-1988 was the most severe ever experienced in Wisconsin and much of the Midwest. It was characterized not only by below normal precipitation, but also by persistent dry air and above normal temperatures. Stream flow measuring stations indicated a recurrence interval of between 75 and 100 years. The effects were most severe in north-central and northeastern Wisconsin. The drought occurred early in the growing season and resulted in a 30-60 percent crop loss, with agricultural losses estimated at $1.3 billion. Fifty-two percent of the state's 81,000 farms were estimated to have crop losses of 50 percent or more, with 14 percent estimated having losses of 70 percent or more. A combination of state and federal drought assistance programs helped the state's farmers recover a portion of their losses. All Wisconsin counties were designated eligible for drought assistance.

The effect of this drought on municipal and private water supplies was not as severe as in 1976-77, with only a few reports of individual wells drying up. A number of municipal water utilities experienced maximum use of their water delivery systems. Many water utilities imposed some type of water-use reduction rules or restrictions, usually involving the limitation of lawn sprinkling and yard watering.


2002 – 2003

This drought extended during the summers of 2002 and 2003 over south central and southeast Wisconsin. Many farmers saw their corn crops wither and there were reports that soybeans stopped growing or the pods stopped filling. Alfalfa hay cutting also suffered. Grass growth slowed dramatically, or stopped altogether. Most locations received less than 1 inch of rain for the first 11 days of August. Madison's Truax Field only measured .61 inches of rain, all of which fell on a single day. Newspaper reports indicated that agricultural experts expected the corn crop yield at harvest time in the fall to be 1/2 to 2/3 of normal, and the outlook for soybeans was worse. Sweet corn yields were expected to be 20 to 30 percent below normal. Some farmers reported that their wheat crop died. Large cracks developed in many fields and the grasshopper populations were above normal. In addition, flowage on most rivers and streams was only 15 to 25 percent of normal for early August.

Only 0.87 inch of rain fell during August 2003 at Truax Field. Both the Milwaukee and Madison August monthly rainfall totals were 3.46 inches below normal. Conditions continued through the month of October 2003 across south-central and southeast Wisconsin. The entire area was in a moderate (D1) to severe drought (D2) status during the month of October. The monthly rainfall at Madison's Truax Field was 1.60 inches, or 0.58 below normal. Only 5 days received 0.10 inches or more of precipitation. Water levels in lakes, rivers, and streams remained below normal for the entire month, and at some spots they were near record-low levels. Newspaper reports indicated that some farmers didn't harvest much of anything in October.

2005

Drought conditions developed over south-central and southeast Wisconsin in July 2005, after the weather pattern turned quiet in mid and late June 2005. The drought classification for south-central and southeast Wisconsin worsened from D0 at the start of the month to severe drought (D2) on July 19, with the exception of the southeast corner consisting of Walworth, Racine, and Kenosha counties. The drought in these three counties worsened to extreme (D3) on July 19th. The drought was preceded by a long period of below-normal precipitation extending back to March 2005. Madison's Truax Field (Dane Co.) reported a 4.08 inch deficit from the beginning of March through the end of July.

A warm and dry August helped strengthen the drought. Rainfall deficits for August ranged from between 2.50 to 3.50 inches across the area. At Madison's Truax Field (Dane Co.), a 3.11 inch deficit was reported in August, setting the March through August deficit at 7.19 inches. Most of the precipitation observed occurred during the middle of the month, helping to relieve the drought status for the southeast corner of the state toward the end of August. The remainder of south-central and southeast Wisconsin remained in severe drought status (D2).

Drought conditions, both agricultural and hydrological, persisted through October over south-central and southeast Wisconsin. Most of south-central and southeast Wisconsin received less than 1 inch of rainfall (normal monthly rainfall is 2 to 2.5 inches) with monthly temperatures averaging about 2 to 3 degrees above normal. Consequently, the drought conditions didn't improve during the month. The drought rating at the end of the month was D2 (severe) in those counties along and south of a line from Madison to Milwaukee. D3 (extreme drought) conditions existed just south of the Wisconsin-Illinois border. D1 (severe drought) conditions existed over those counties north of a line from Madison to Milwaukee. Newspaper and weather reports indicated that due to the spotty nature of the just-completed warm-season convective showers, soil moisture conditions varied greatly across


individual counties, resulting in varying yields. Harvest reports indicated that overall corn and soybean yields didn't suffer as much as originally expected in July. Undoubtedly there were monetary crop losses due to the drought; however estimations were unavailable from county/state agricultural agencies. Drought conditions continued across south-central and southeast Wisconsin through November, but did show improvement by the end of the month due to above normal precipitation.


Historical data indicates that drought occurs approximately once every five years in Dane County. Using the formula established in Section 4.2.1 Profile Methodology, the assessment reflects (15 drought incidents over [divide by] 72 years) x 100 = 20 percent chance of occurrence and a likely occurrence rating.

Impact Assessment

Direct

Dane County is most vulnerable to agricultural drought. Obvious impacts include the losses associated with crop and livestock yields. Dane County is also vulnerable to hydrological drought. Hydrological impacts of a prolonged drought include lower water levels in the lakes and ponds of the County, reduced stream flow, degradation or loss of wetlands, decreased water quality, and lowering of the water table.

Indirect

The indirect impacts of drought are far reaching. The cascading effects of drought provide a more accurate picture of the drought’s affect on the region and the nation. Unlike many other natural hazards, drought may extend indefinitely, but as with all disasters, the more prolonged the event, the greater the damage and indirect impacts. Less obvious impacts of agricultural drought include increased incidents of insect infestation, plant disease and wind erosion. These problems also impact forests and other wild areas, which can reduce levels of growth or result in large areas of dangerously dry vegetation, which in turn increases the risks for wildfires. The incidence of forest and grassland fires increases substantially during extended droughts. In addition, the loss of vegetation and drying and hardening of the ground can result in flooding, even from average rainfall, as rainwater is unable to soak into the soil.

The National Drought Mitigation Center (NDMC) at the University of Nebraska-Lincoln suggests examining indirect impacts of drought using three broad categories: economic, environmental, and social impacts. In Dane County, most economic impacts occur in agriculture and recreational sectors because these sectors rely on water supply and quality. The resulting income loss from these sectors creates ripples which impact a wide range of other aspects in the local economy. Retailers that supply these industries also face reduced business which in turn impacts suppliers and production levels. This loss of product turnover may lead to unemployment, increased credit risk, loss of tax revenue, and other economic considerations. Depending on the severity, geographic extent and duration of a drought, every sector of a local economy could experience indirect social and economic impacts. Specific examples include:

Agricultural Production

• Reduced yields and crop loss due to water stress, insect infestation, and plant disease.


• Increased irrigation cost for crops. • Reduced productivity of pastureland. • Increased feed costs. • Reduced milk production. • High livestock mortality rates. • Disruption of livestock reproduction cycles. • Wind and water erosion of exposed topsoil. • Cost of new or supplemental water supply. • Income loss.

Recreation and Tourism

• Damage to fish habitat and/or reduction of fish populations. • Income loss to manufacturers, suppliers, and retailers of recreational equipment,

particularly fishing and boating equipment.

Water Utilities

• Increased costs for development of new water sources e.g., cost to drill new, deeper wells.

Residential

• Direct loss of trees, especially young ones. • Increased susceptibility of trees to wind damage. • Increased risk of wildfire in rural areas.

General

• Economic losses to businesses directly dependent on agricultural production e.g., farm cooperatives, food processors, and dairies.

• Unemployment from drought-related declines in production. • Revenue losses to state, and local governments. • Fewer agricultural producers due to bankruptcies or cessation of farming operations. • Conversion of farmland to suburban development. • Increased demand on disaster assistance programs. • Increase in food prices.


The severity of drought impacts to the county depends on the type of drought. Agricultural drought, for example, will affect rural and farming communities more severely than urban communities. Socio-economic drought will impact the industries most closely tied to water resources more than unrelated industries. Since agriculture is a significant part of the Dane County economy, and the indirect impacts of drought are extensive and long-lasting, the magnitude/severity rating of a drought is considered critical.


The vulnerability of the people, buildings, and economy of Dane County is very difficult to quantify. Typically, structures and people are not directly vulnerable to drought, though secondary or indirect impacts may eventually increase vulnerability ratings. As discussed in the impacts section, the potential impacts for drought are systemic. However, some areas


are more vulnerable overall than others and, therefore, benefit from adequate mitigation planning and implementation. For Dane County, the agricultural economy is the most vulnerable to drought and will benefit the most from mitigation efforts. Overall, property and people are not highly vulnerable to drought. Economic resources tied to agricultural production are extremely vulnerable to drought, with secondary vulnerabilities attributed to economic income based on recreational use of natural resources. An overall vulnerability rating for drought is medium.

Vulnerability to Agricultural Drought

Dane County ranks as one of the country’s leading agricultural producers. In 2007, the total market value of agricultural products sold in Dane County was about $280 million (see Table 4.7).

Table 4.7 Major Agricultural Commodities in Dane County in 2007

Item Quantity Rank Market value of Agricultural Products Sold ($1,000)

Total value of agricultural products sold 470,593 1

Value of livestock and poultry 336,187 1

Value of crops including nursery 134,406 1

Top Five Commodities – Value of Sales ($1,000)

Dairy products 206,247 3

Grains, oilseeds, dry beans and dry peas 109,384 1

Cattle and Calves 46,362 3

Nursery, Greenhouse, Floriculture and sod 13,521 6

Hogs and Pigs 5,031 6

Top Five Commodities – Livestock Inventory (number)

Cattle and calves 145,460 2

Layers 75,052 9

Pheasants 26,247 9

Hogs and Pigs 21,977 4

Broilers and Other Meat-type Chickens 9,962 9

Top Five Commodities – Crop Area (acres)

Corn for grain 172,733 1

Forage-land used for all hay and haylage, grass silage, and green chop 76,970 4

Soybeans for beans 71,684 1

Corn for silage 32,780 2

Wheat for grain, all 12,045 7 Source: 2007 Census of Agriculture, Dane County Profile, USDA National Agricultural Statistics Service. Rank is compared to other 71 counties in the state.


This is the highest overall value in the state, and in the top 2 percent nationwide. This is a 64 percent increase from the 2002 Census.10 There are approximately 3,331active farms in the County, covering 535,756 acres. The average size of a farm is 161 acres. Overall, the size of farms has decreased 10 percent since the 2002 Agricultural Census, but the number of farms and overall farmland use has increased 15 percent and 4 percent respectively. Crop sales account for 29 percent of market value production, while livestock sales account for 71 percent. This is a 64 percent increase over the 2002 Census. Corn, hay, and soybeans are the major crops grown in the County, accounting for more than 354,000 acres of cropland.

In addition to the value of the agricultural products, the costs and values of agricultural processing must be considered. The 2007 Census of Agriculture notes an additional $18.5 million of income for farm-related sources such as rent, custom work, or recreational services. A 1996 study cited in the Dane County Executive’s “Design Dane” report describes that impact as more than $430 million in wages and salary (5.6 percent of the Dane County total), $936 million in value-added income (7.8 percent of the County total) and 18,900 jobs (6.3 percent of the County total).

Vulnerability to Socioeconomic Type Drought

Socioeconomic drought occurs when the demand for an economic good exceeds supply as a result of a weather-related shortfall in water supply. The greatest potential social impact of drought for Dane County residents is lack of water for household and recreational uses, while the greatest potential economic impacts remain agriculture and recreation-derived income.

The Dane County Wisconsin Comprehensive Plan (DCWCP) offers the following observations about water supply for the county: “Groundwater supplies nearly all of the water for domestic, commercial and industrial uses in Dane County. Over 60 million gallons per day (mgd) of groundwater is withdrawn and used- about 140 galloons per person per day. Most of this water is returned to surface water after use. Public water supplies account for about 75 percent of total groundwater use. This includes water withdrawn and used in municipal and private systems for residential, industrial, and commercial purposes. Urban areas account for 80 percent of groundwater use. The City of Madison is the largest single consumer, withdrawing over 30 mgd, and accounts for over half of the total use in the County.”11

Thirty-two water utilities supply water to urban service areas, with a total population of approximately 352,000. The remainder of County residents (approximately 60,000 people) obtains water from private wells. The 2000 Census estimates 21,000 private wells are in service for over 55,000 residents.12

The DCWCP does identify ten plans, projects, or commissions which address water resources. These include state-sponsored plans (the Department of Natural Resources Basin Plan and the Department of Natural Resources Fisheries, Wildlife and Habitat Management Plan for Wisconsin), regional efforts (Dane County Water Quality Plan and the Regional Hydrologic Model and Monitoring Program), and county programs (Lakes and

10 USDA, National Agricultural Statistics Service, 2007 Census of Agriculture. Available online at http://www.agcensus.usda.gov/Publications/2007/Full_Report/Volume_1,_Chapter_2_County_Level/Wisconsin/index.asp last accessed March 19, 2009. 11 Dane County Wisconsin Comprehensive Plan, p 53, October 2007 12 Dane County Wisconsin Comprehensive Plan, p 53, October 2007


Watershed Commission, Shoreland and Wetland Zoning, Floodplain Zoning, Stormwater and Erosion Control, the Dane County Land and Water Resource Management Plan, and the Waterbody Classification and Riparian Management Project). Each of these plans addresses the social impacts of water supply. Drought impacts may be inferred from these resources, and the potential exists to gather greater tangible data in these efforts, which will improve the ability to analyze the impact of drought on the county and help drive mitigation efforts.



The level of analysis needed to calculate the potential for future drought losses encompasses a number of subjective variables. To calculate the future impact of agricultural drought, for example, first a unit of impact must be selected. Assuming fiscal loss to farmers is the primary concern, data would then need to be collected regarding the predictions of future crop yields for the year, statistical information based on rainfall-to-harvest yields to estimate impact of weather and water on the growth of the crop, predicted crop cost/sales ratios, and then an extrapolation of various scenarios, all of which must be considered for market value of the crop in question, which varies yearly and sometimes seasonally. Accurate prediction of these goods is probably unreliable more than one season in advance. Since droughts are often regional, long-term hazards, this method of analysis does little to implement proactive mitigation efforts.

The same is true for estimating socioeconomic losses of drought, which would incorporate all of the previous data plus expected water demand for household and recreational use, models for impact on lake and stream levels, and comparative data to estimate revenue lost by lower utilization of the recreation. Obviously, then, potential future losses are best discussed by patterns of assumption.

Given the occurrences of past droughts, it is reasonable to assume that there is real risk of a significant drought for Dane County. A considerable portion of Dane County’s economy is reliant on agriculture and is therefore, vulnerable to drought losses. There is, however, no readily available model or data that can be used to quantify that vulnerability. Based on the documented state-wide losses for the 1987-1988 drought it is possible to experience a 30-60 percent loss in crops. Assuming a severe drought will result in a 50 percent loss of crops, this equates to a potential loss of revenue of $67 million, based on 2007 dollars for crop market value. Assuming drought also impacts livestock production and sales, but to a lesser extent, the planning team assumed a 25 percent loss of livestock sales. This estimate equates to a potential loss of revenue of $84 million in livestock sales. Overall, Dane County could lose $151 million in agricultural revenue during a severe drought, or 32 percent of the total agricultural production revenue.

Development Trend Assessment

The projected growth trends in Dane County will result in increased demand on water for household, commercial and industrial use poses concerns regarding the existing water supply for Dane County. These concerns are addressed in the plans listed above. Protecting existing water supplies is a major component to drought mitigation, and therefore the future growth of the county, and the associated impact on water supplies that will serve as indirect impacts of drought, are already being addressed. As recommended previously, the increased incorporation of drought data collection into these plans will enhance water protection and quality efforts for the county, as well as provide statistical data for a drought risk analysis.


The Dane County Water Quality Plan notes that “although there is a relatively unlimited groundwater supply in the county, it is critically important that the quality of groundwater be protected for these uses. Groundwater is also very important in providing baseflow discharges to wetlands and streams, which support these resources especially during periods of dry weather.”13 The commercial impact on ground water is currently considered a more significant threat to the county’s water supply and quality than a prolonged drought, as addressed in the Water Quality Plan and the Comprehensive Plan, but the potential for cascading affects is addressed. The Water Quality plan also notes that “the removal of groundwater, and its eventual return to surface water in a different location, can have indirect but serious impacts on local hydrology and water quality conditions.” Though this impact is “particularly pronounced in urban areas”, it potentially threatens the recreational incomes of watersheds dependant on the flow of underground water sources, which may already be depleted during a drought.

Groundwater (water-table) has been above normal in 2008 and 2009 due to heavy rains in August, 2007, record snowfalls for the 2007-08 winter season, heavy rains in June, 2008, and above normal snowfall during the 2008-09 winter season. From February, 2006, through February, 2009, there was a surplus of about 26 inches of precipitation at Madison’s Truax Field. Well into the 2009 summer one could still see water in some low spots in Dane County farm fields and other lows spots that normally become dry during summers.


Overall, Dane County experiences a medium risk from drought. Though occurrences are fairly likely and are geographically widespread, there is no economic or medical data to indicate that droughts have a serious impact on the county in terms of population, essential infrastructure, general property, or cultural and historic resources. Agricultural drought, which has the greatest fiscal impact on the county, is the larger concern. The potential impact on recreation due to drought is high, but again there is no data to indicate a strong correlation between droughts and loss of revenue from water-based recreation.

Table 4.8 provides the summary for how all aspects of the hazard profile were evaluated to establish an overall hazard rating.

Table 4.8 Overall Risks for Drought


Geographic Extent Extensive 4

Probability of Future Occurrence Likely 2

Vulnerability Assessment Medium 2

Impact Magnitude and Severity Critical 3

Overall Risk Rating Medium 2.75

13 Dane County Water Quality Plan, 2004, http://danedocs.countyofdane.com/webdocs/PDF/capd/waterq/WaterQPlan_chap2.pdf, p 31


4.2.4 Flood

Much of the following hazard profile is the result of incorporating a previous stand alone flood mitigation plan developed by the County in 2003 and adopted in 2004. The Dane County Flood Mitigation Plan was incorporated into this multi-hazard mitigation plan during the 2009 update. This profile includes more detail than many of the other hazards, due to the availability of information in the Flood Mitigation Plan and associated extensive analyses of this hazard. In addition it is one of Dane County’s most costly, and complex, hazards.

Description14

Flooding is the accumulation of water within a water body (e.g., stream, river, lake, and reservoir) and the overflow of excess water onto adjacent floodplains. Floodplains are lowlands, adjacent to water bodies that are subject to recurring floods. Floods are natural events that are considered hazards only when people and property are affected. Nationwide, hundreds of floods occur each year, making it one of the most common hazards in all 50 states and U.S. territories (FEMA, 1997).

There are a number of types of floods in Dane County, including the following:

• Riverine flooding, including overflow from a river channel, flash floods, ice-jam floods, and dam break floods

• Local drainage or high groundwater levels • Fluctuating lake levels • Debris flow

The most common type of flooding event is riverine flooding, also known as overbank flooding. Riverine floodplains range from narrow, confined channels in the steep valleys of mountainous and hilly regions, to wide, flat areas in plains and coastal regions. The amount of water in the floodplain is a function of the size and topography of the contributing watershed, the regional and local climate, and land use characteristics. In steep valleys, flooding is usually rapid and deep, but of short duration, while flooding in flat areas is typically slow, relatively shallow, and may last for long periods of time.

The cause of flooding in large rivers is typically prolonged periods of rainfall from weather systems covering large areas. These systems may saturate the ground and overload the rivers and reservoirs in numerous smaller basins that drain into larger rivers. Localized weather systems (i.e., thunderstorms), may cause intense rainfall over smaller areas, leading to flooding in smaller rivers and streams. Annual spring floods, due to the melting of snowpack, may affect both large and small rivers and areas.

While there is no sharp distinction between riverine floods, flash floods, ice jam floods, and dam-break floods, these types of floods are widely recognized and may be helpful in considering the range of flood risk and appropriate responses:

Flash flood is a term in wide use by experts and the general population, but there is no single definition or clear means of distinguishing flash floods from other riverine floods. Flash floods involve a rapid rise in water level, high velocity, and large amounts of debris, which can lead to significant damage that includes the tearing out of trees, undermining of buildings and bridges, and scouring new channels. The intensity of flash flooding is a

14 Wisconsin Emergency Management “State Hazard Mitigation Plan 2008” pp 4-14 to 4-16.


function of the intensity and duration of rainfall, steepness of the watershed, stream gradients, watershed vegetation, natural and artificial flood storage areas, and configuration of the streambed and floodplain. Dam failure (see Dam failure hazard profile) and ice jams may also lead to flash flooding. Urban areas are increasingly subject to flash flooding due to the removal of vegetation, covering of ground cover with impermeable surfaces, and construction of drainage systems.

Ice jam floods are primarily a function of the weather and are most likely to occur where the channel slope naturally decreases, culverts freeze solid, reservoir headwaters, natural channel constructions (e.g., bends and bridges), and along shallows.

Local drainage floods may occur outside of recognized drainage channels or delineated floodplains due to a combination of locally heavy precipitation, a lack of infiltration, inadequate facilities for drainage and stormwater conveyance, and increased surface runoff. This type of flooding has not typically been mapped by the NFIP, and the NFIP only requires local governments to impose land use regulations in a mapped floodplain. Such events frequently occur in flat areas, particularly during winter and spring in areas with frozen ground, and also in urbanized areas with large impermeable surfaces. High groundwater flooding is a seasonal occurrence in some areas, but may occur in other areas after prolonged periods of above-average precipitation. Losses associated with local drainage and high water tables are similar to flood, therefore they are not analyzed as a distinct hazard.

Dane County’s Flood Problems

During the development of the initial Flood Hazard Mitigation (2003) a comprehensive assessment of the impacts and problems associated with floods in Dane County was performed using a combination of survey, public meetings, interviews and GIS. The flood mitigation planning committee’s analysis revealed that flooding in Dane County is the result of a combination of highly complex factors that can be distinguished by four main categories: contributing influences, resulting impacts, conflicts, and complicating factors. The category of contributing influences can be further broken down into controllable variables and uncontrollable variables.

Controllable variables are those that can be adjusted or modified through regulation of human behavior. Uncontrollable variables are those that are difficult if not impossible to manipulate. In describing the flooding problem, the uncontrollable variables are those that describe the natural process and the lay of the land. None of these variables are problematic in themselves, but combined, they provide an accurate portrayal of where and what kinds of problems are likely to occur. Even so, these factors only become problematic when structures or developments are located in areas of vulnerability. Likewise, none of the controllable variables are problematic unless the uncontrollable variables indicate a risk if a certain use or practice is instituted at a certain site or location. The controllable variables can be adjusted depending on the conditions presented or likely to be presented by the uncontrollable conditions.

Contributing influences to flooding in the County include:

• Controllable − land use; − zoning regulations; − erosion control management practices; − building codes; − education;


− amount of impervious surfaces; − general engineering practices; − loss of wetlands; − insufficient capacity for stormwater; − debris in streams; − and development in high-risk areas.

• Uncontrollable − soil type; − local topography; − depth of the water table; − floodplains; − weather events; and − climate change.

Resulting impacts of flooding include:

• residential and commercial flooding; − flooded basements; − sewer backups; − structural damage to buildings; − damage to the contents of buildings.

• road, shoulder and ditch washouts; • crop loss;and • health and safety concerns.

Each of these categories comes into focus depending on the scale of the analysis. Generally, contributing influences are associated with a regional perspective, and resulting impacts are associated with a site-specific perspective on the flooding problem. Defining the problem in purely physical terms (watersheds, land use, rivers, homes, roads, crops) is not sufficient to completely understanding the flooding problem in the County. Political, social, governmental, and environmental conditions or positions frame and define the problem. Some of the conflicts and complicating factors recognized in this process are:

Conflicts:

• Cognitive Conflicts (Search for the truth) − hydrologic systems are dynamic systems, regulations treat them as static systems; − varying levels of public awareness; − interrelatedness of flooding with many other variables makes an objective

comprehension of problem difficult; − low levels of communication and cooperation across borders distort reality.

• Distributional Conflicts (Search for what is acceptable) − uneven regulatory field for local units of government; − discrepancy in need and desire for County intervention; − desire for a quick, local solution to a complex, regional problem; − differing social expectations for lake level and waterway aesthetic and function; − discernment of the appropriate party to solve the problem.

• Value Conflicts (Search for what is good − varying and conflicting economic, social, and environmental values; − distrust of higher levels of government.

Complicating Factors:


• high level of regulatory complexity; • roles for programs and government departments are unclear.

Contributing Influences

The survey and assessment of past flood events shows that there is a wide range of factors that contribute to flooding problems. Dane County is primarily a drainage area. The County fully or nearly fully contains the headwaters of most of the rivers and streams that flow through and out of the County. While there are predictors of where floods will occur and the impacts that will result, Dane County does not have a major river and associated floodplain system that can be used to predict a damage potential given a certain probability flood. There are exceptions such as Black Earth Creek and Koshkonong Creek where flooding does typically occur as riverine flooding of a well-defined floodplain. The Yahara River and chain of lakes is another such exception. Flooding around the chain of lakes is not typical riverine flooding, however, the impact of flooding can be readily predicted given lake level elevations.

Development in Flood-prone Areas (Areas with inherent flood risk)

There are areas of the County that if developed, have an inherent risk of flooding and resulting flood damage. These typically are areas that in their natural state, are associated with floodplains, low lying shorelands, wetlands (existing or drained) and steep slopes with highly erodible soils.

Floodplains

Developing and building in areas with a natural flood risk is a well-documented cause of subsequent flood damages. The floodplain is very simply the land that has been or may be covered by floodwater during a flood. A cross-sectional view of a typical floodplain is illustrated in Figure 4.5. The 100-year floodplain, 1 percent annual chance flood, Special Flood Hazard Area, and Base Flood are different terms for the same level of flooding, and the level that floodplain regulation in the United States is based upon. The floodway is a zone within the Special Flood Hazard Area that has even stricter regulations, as it is typically where flood flows are highest and deepest. Shallower flooding with slow or no velocity happens in the “flood fringe.” To build or develop in a floodplain exposes the owner to an inherent risk of flooding at some point in the future. Figure 4.6 shows the location of mapped floodplains.


Figure 4.5 Floodplain Definition Sketch.

Source: FEMA, August 2001.

The locations and delineation of floodplain boundaries, however, are not static. Floodplains change over time. Though they are represented as a line on a Flood Insurance Rate Map (FIRM), floodplains and flood risk are not black and white. The floodplain maps are designed to indicate areas with a risk of flooding, but those areas are constantly changing. Increasing impervious surface areas with new development, soil saturation, rainfall intensity, stream conditions, shoreland and wetland modifications (both restoration and degradation), and stormwater management practices all affect the extent to which flooding will occur. And these influences are constantly changing as well. The survey identified frequent reports of areas that never flooded in the past, but do flood now.

In addition to this, there is a widely held perception that the 100-year floodplains shown on a FIRM represent a clear boundary of flood risk. On one side of the line, there is a flood risk, on the other side, there is not. This is not what the maps are intended to show. Flood risk is a continuous spectrum and the floodplains shown on the FIRM represent but one increment of that spectrum, the 1 percent probability of flooding. For regulatory and insurance purposes, a line has to be drawn somewhere. There is a danger in using this line as the end-all in determining flood risk. The maps are intended to represent the risk as accurately as possible, but they are merely a prediction of the extent of flooding that could occur in the future, based on a snapshot of present and past conditions.

Nevertheless, the location of mapped floodplains is a major indicator of where flooding will occur in the County and it is a major indicator of subsequent damages. While the accuracy of FEMA’s Flood Insurance Rate Maps (FIRM) has been the subject of much debate, these maps still provide the best information available regarding the location of floodplain boundaries.

Hydric Soils

Though mapped/regulatory floodplains are a good predictor where flooding occurs, floodplains do not account for all of the flooding in the County. The location of certain soil types, hydric soils in particular, is also a good predicator of where flooding is likely to occur.


Hydric soils are formed under conditions of saturation, flooding, or ponding long enough during the growing season to develop anaerobic conditions in the upper part. They are a good indicator of the historic locations of wetlands or other wet areas. As such, development in areas with hydric soils is another prime indicator of where flood damages are likely to occur, especially in areas where urbanization has not altered the natural hydrology of the area. Figure 4.6 shows the locations of hydric soils in Dane County.

Topography

The topography of the County affects the spatial extent of flooding. In the western portion of the County where topography is most exaggerated, flooding occurs in small areas, yet the water flow rate is much higher than in the eastern part of the County. There, landowners experience expansive flooding, since the water is able to stretch across the landscape more easily. This contributes to greater crop loss. Topography and hydric soils are useful indicators of the frequency and extent of flooding outside the floodplain.

Impediments to the Flow of Water

Changes in stream conditions and impediments to the flow of water were identified as a significant factor in increasing flood problems along the rivers and streams of the County. Impediments to flow reduce the overall capacity of the stream to convey water and cause water to back-up behind the blockage. These impediments include blockages caused by accumulation of sediment, over growth of weedy, non-native vegetation, or excessive debris in the stream channel. Reduced conveyance capacity and blockages can and do occur in all components of the natural and human-made components of the drainage system, including detention ponds, stream channels, drainage ditches and culverts.

Debris in the Drainage System

Debris in streams has been identified as a significant problem in numerous areas of the County. Debris refers to a wide range of materials that may include tree limbs and branches that may accumulate naturally or garbage and trash that has been dumped into channels or drainage ditches. There is often a very fine line between debris that should be removed to improve conveyance capacity and natural material that is necessary for fish and wildlife habitat.

Silt and Sediment

Silt and sediment has also been identified as a significant impediment to flow in numerous streams and ditches of the County. Farmlands and construction sites typically contain large areas of exposed soil. Surface water runoff can erode soils from these sites and carry sediment into downstream waterways. Erosion also occurs along streambanks and shorelines as the volume and velocity of flow destabilizes the banks and washes away the soil.

Sediment suspended in the water tends to settle out where the flowing water slows down. It can clog storm sewers, culverts, and ditches and reduce the water conveyance capacity of rivers and streams. Not only is the drainage system less able to carry water, but the sediment in the water also reduces light, oxygen, and water quality and often carries agricultural chemicals and other pollutants into the water.


Figure 4.6 Mapped Floodplains and Hydric Soils in Dane County


The erosion control elements of the County’s Stormwater Management and Erosion Control ordinance are designed to address these issues. Even with the ordinance in place, however, streams that are currently restricted by sediment will remain restricted unless the existing sediment is removed.

Human Constructed Impediments to Flow

Bridges, culverts, and drainage ditches that are improperly sized have been noted as a significant factor in restricting the flow of water and exacerbating flood problems. This does not appear to be a systematic problem, but rather one that occurs in a few isolated areas of the County.

Loss of Wetlands

Wetlands are often found in floodplains and low-lying areas of a watershed. Many wetlands receive and store floodwaters, thus peak flows and volumes of floodwaters. Wetlands also serve as a natural filter, which helps to improve water quality. Wetland loss has affected all of Dane County. Wetlands have been tiled and drained to produce fertile farm fields and they have been filled and paved to prepare for development. Wetlands on the Yahara Chain of Lakes have also been lost during recent flood events as rising floodwaters detach and lift sections of marsh. The floating marsh sections have been subsequently removed to eliminate the navigational hazards they posed. Lakes in the Yahara Chain of Lakes have lost between half and nearly all of the wetlands associated with them since 1835.

Healthy wetlands have the potential to store large volumes of floodwater. As wetlands become destroyed or degraded, their capacity to store water may be reduced. Water that would otherwise have been stored in the wetlands then contributes to increasing flood levels and flows. The maintenance and restoration of wetlands has the potential to be a very effective flood management tool.

Upland Development and Stormwater Issues

Dane County is among the fastest growing and developing counties in the State of Wisconsin. The challenges of managing this rapid development are wide-ranging; however, one of the more significant impacts is the effect of development on the hydrology of the watershed. The effect of upstream development on downstream properties was widely recognized as significant contributing factor in Dane County’s flood problems. In fact, development and other changes to the landscape in areas far outside the floodplain can have a profound impact on the magnitude and frequency of downstream flooding. This is a highly complex issue that includes elements of land-use decision-making, property rights, intergovernmental cooperation (or lack of), as well as the hydrology of the watershed and stormwater management practices. Many of these elements are well beyond the scope and charge of this Plan, however, the issues as related to stormwater management can at least be framed here.

The Dane County Board of Supervisors adopted the Erosion Control and Stormwater Management Ordinance effective August 22, 2002, acting on the recommendation of the Dane County Lakes and Watershed Commission after 11 public hearings and hundreds of hours of meetings with citizens, technical experts, developers, builders, local municipalities, and other stakeholders. The Board found that construction site erosion and uncontrolled stormwater runoff from land disturbing and land development activities have significant adverse effects upon regional water resources including the health, safety, property and general welfare of the community, diminishing the public enjoyment and use of natural


resources. The Board also found that effective erosion control, sediment and stormwater management depends on proper planning, design, timely installation and continued maintenance of erosion control and stormwater management practices. Specifically, they found that soil erosion and stormwater runoff can:

• carry sediment, nutrients, pathogens, organic matter, heavy metals, toxins and other pollutants to regional lakes, streams and wetlands;

• diminish the capacity of water resources to support recreational and water supply uses and a natural diversity of plant and animal life;

• clog existing drainage systems, increasing maintenance problems and costs; • cause bank and channel erosion; • increase downstream flooding; • reduce groundwater recharge, which may diminish stream base flows and lower water

levels in regional lakes, ponds and wetlands; • contaminate drinking water supplies; • increase risk of property damage and personal injury, and; • cause damage to agricultural fields and crops.

Effective January of 2006, revisions to the erosion control and stormwater management ordinance were made to meet state standards for infiltration and to make shoreland erosion control requirements of Chapter 11 consistent with Chapter 14. More information on the ordinance can be referenced in Section 4.4.2 Additional Capabilities.

The Effects of Urbanization

Urbanization is one of the most severe land use impacts in terms of its lasting effects on hydrology, due to the much higher percentages of impervious or paved areas covering the land. Rural land surfaces are almost completely pervious, while about one-third of the land surface in urban areas is covered by rooftops and paved areas. The main effects of urbanization on the hydrology of an area include:

• An increase in the total amount of rainfall running off the surface of the land; • A decrease in the amount of rainfall infiltrating into the soil; • More rapid runoff and much higher peak flows; and • Reduced baseflows in streams during dry weather periods.

In addition to generating more surface runoff, which erodes the land surface and washes off more pollutants, the hydrologic effects of urbanization have less direct but more important downstream impacts. The increased peak storm runoff rates and reduced base flow associated with urbanization have serious negative impacts on receiving streams, usually resulting in erosion, sedimentation, streambank instability, and flooding. Combined with reduced base flow, the scenic, recreational and habitat values of the receiving streams can be seriously degraded unless a vigorous effort is made to provide management practices and programs to counter the effects of urbanization.

Climate Change

The earth’s climate is predicted to change because human activities are altering the chemical composition of the atmosphere through the buildup of greenhouse gases – primarily carbon dioxide, methane, nitrous oxide, and chlorofluorocarbons. The heat trapping property of these greenhouse gases is undisputed. Although there is uncertainty about exactly how the climate will respond to the increased concentrations of greenhouse gases, observations indicate that detectable changes are already occurring. There will most


likely be increases in temperature and changes in precipitation, soil moisture, and sea level, which will likely have adverse effects on many ecological systems as well as on human health and economy.

Water resources are affected by changes in precipitation as well as by temperature, humidity, wind, and sunshine. Because evaporation from streams and lakes is likely to increase with warmer climate, it could result in lower river flow and lower lake levels, particularly in the summer. In addition, there is also a trend toward fewer, but more intense rainfall events, which in turn could lead to both increased droughts and increased flooding. Groundwater supplies could also be reduced if streamflow and lake levels drop. This increasing variability has to be considered in water resource planning for the future.

Geographic Extent

Flooding is generally a regional phenomenon in Dane County. The impact varies based on geographic location to waterways, soil content and ground cover, and construction. The extent of the damage of flooding ranges from very narrow to widespread based on the type of flooding and other circumstances such as previous rainfall, rate of precipitation accumulation, and time of year. Dane County’s mapped floodplains are shown in Figure 4.7. It is considered to have a significant geographic impact rating. Refer to the County profile section of this plan for a thorough description of the County’s major drainage basins and associated rivers, streams and lakes.

The 2003 flood survey included an assessment of the impacts and problems associated with floods in Dane County. The survey and associated maps describe the causes and effects of flooding as well as the geographical location of each problem. Map and Flood Mitigation Plan Survey data were transposed into a geographical information system (GIS) for further analysis.

The results of the process were represented as points on a countywide map. Each point represents an area delineated on a map by a survey respondent and carries with it a unique set of flooding problems recorded by the survey. This area is referred to as a “problemshed.” The total number of problemsheds recorded through the survey is 184. The land area of the problemsheds range from 100’s of acres to down to a single block. The severity of the problem or problems that a problemshed represents also ranges from severe to minor. Figure 4.7 shows the geographical distribution of the points or problemsheds, within the watersheds of the County.


Figure 4.7 Watershed and Problemshed Locations


Figure 4.8: The Distribution of Flood Problem Areas across the County, Based on the Flood Mitigation Plan Survey

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Dane County received Presidential disaster declarations for widespread flooding seven times since 1971. Significant damages were also recorded in 1996. Cumulative losses for these disasters exceed $65 million, including private, public and agricultural damages. Damage assessment summaries for those years are shown in Table 4.9. As shown, losses caused by widespread flooding have been substantial. Private and public losses shown as “estimated” are based on a compilation of local damage assessment figures. Public and private losses shown as “actual” are based on FEMA public and private assistance program payments. Agricultural losses are based on Dane County UW-Extension and USDA Farm Service Agency (FSA) estimates. Figure 4.9 shows the number of events, deaths and injuries related to flood events for the entire state of Wisconsin from 1982 through 2008. Dane County is tied for the fifth most total flood events.


Table 4.9 Damages from Disaster-Declaration Floods in Dane County (1971-2008)

Year Loss Type Amount Year Loss Type Amount

Private losses: Not available Private losses: $5.0 million (est.)

Public losses: $180,000 (actual**) Public losses: $1.1 million (actual) 1978

Agricultural: Not available

2000

Agricultural: $3.2 million (est.)

Private losses: $30,343 (actual*) Private losses: $3.3 million (est.)

$585,000 (actual*)

Public losses: $37,000 (actual**) Public losses: $1.8 million (est.) 1990


2007


Private losses: $11.5 million (est.) Private losses: $7.45 million (est.)

$1.75 million (actual*)

Public losses: $1.1 million (actual) Public losses: $6.07 million (est)

$1.5 million (actual **)

1993

Agricultural: $10 million (est.)

2008

Agricultural: Not Available

Private losses: $6.8 million (est.)

Public losses: $1.7 million (est.) 1996

Agricultural: $2.5 million (est.)

Source: Dane County Emergency Management; * Federal Individual Assistance Payout; ** Federal Public Assistance Payout


Figure 4.9 Total Flood Events for Wisconsin 1982-2008

Source: National Weather Service, 2009

A brief description of past flood events, and their impacts are listed below. Accounts prior to 2002 are taken from the 2004 Dane County Flood Mitigation Plan. More recent events are pulled from the National Climactic Data Center Database.


Spring, 2009

During the 2009 update of this plan flood problems began in early March in some areas of the County, notably the northern portion. Road flooding and some residential flooding was reported in the towns of Vienna and Roxbury. Fish Lake in the Town of Roxbury was threatening residential properties with rising lake levels. Substantial rainfall on still-frozen ground may have been a contributing factor to this flooding. Several roads were underwater and closed around Crystal Lake. 22 Recreational vehicles or other structures at the Crystal Lake RV Resort and Campground were substantially damaged.

July 11, 2008

A series of thunderstorms dumped heavy rains of 1 to 3 inches within an hour or two that generated flash flooding. May urban roads were flooded with fast-flowing water of 1 to 2 feet in depth. Basement flooding was noted with damage to contents. A series of thunderstorms developed into clusters and short lines that moved east-southeast through southern Wisconsin. Due to a moist atmosphere, heavy rains were reported overnight in the range of 1 inch to slightly over 4 inches. Due to a saturated ground, flash flooding was the result.

June 7, 8, & 12, 2008

Heavy rains resulted in flash flooding as water reached depths of 3 feet or more and several cars stalled. This was the last of 6 flash floods in Dane County on 3 different days. The first one occurred on June 7th, the next two on June 8th, and the last three on June 12th. In all six cases, damage to homes, businesses, and crops was noted. It was nearly impossible to break down the damages by flash flood event. Therefore, the collective breakdown is provided in this last June 12th flash flood StormData entry for Dane County. Some farm fields remained flooded into early July. The breakdown for residential home losses were: 2,020 minimally affected, 248 with minor damage, 109 with major damage, and 3 destroyed (total of $6.797 million). The breakdown for business losses were: 152 with minor damage, and 3 with major damage (total of $677 thousand). Crop losses were estimated at $64.6 million. Public sector damage was about $6.067 million. Several roads and bridges sustained damage. A series of clusters of strong to severe storms ahead of a cold front moved east/northeast across south-central and southeast Wisconsin. Copious amounts of moisture were available that allowed repeated heavy rains. Additionally, there was sufficient vertical wind shear to allow for the generation of supercell thunderstorms with rotating updrafts that led to seven tornadoes in this part of the state of Wisconsin.

August 22, 2007

Flash flooding occurred due to repeated thunderstorms with heavy rains on top of a saturated ground. From Madison to Sun Prairie many roads had fast-flowing water depths of 6 inches to 1 foot, and several were closed. Sandbagging also took place to control the flash flooding. A 1-hour rainfall total of 2.26 inches was measured by a spotter in Madison. Soil erosion and crop damage also occurred on several other farms in that area. Additionally, a few basements had water damage to contents. August, 2007, rainfall totals in inches include: 15.18 at Madison Truax Field, 14.58 at the UW-Charmany Farm, 14.92 at Mazomanie, 14.43 in Middleton, 18.48 near Mt. Horeb, 16.37 in Stoughton, 15.74 in Sun Prairie, and 13.49 at the UW Arboretum. Up to 20 may have fallen in the southwest corner.

During the afternoon and evening hours of August 22nd, the second round of storms for the calendar day moved across south-central and southeast Wisconsin. The clusters or short


lines of storms moved east at a speed of about 30 knots (35 mph), and generated damaging downburst straight-line winds that toppled trees and power-lines, and heavy rains that triggered flash flooding. Synoptically, a stationary front stretched from northern Iowa to Wisconsin/Illinois border. Warm, moist, unstable air flowed north over the front in association with an upper-level short-wave trough, resulting in thunderstorm generation. Hourly rainfall rates peaked around 2 inches. By the end of August, 2007, many locations in south-central and southeast Wisconsin established new August rainfall records and all-time/any month rainfall records. Many locations measured 10 to over 20 inches for the month of August, 2007, or about 200 percent to over 400 percent of normal. Normal August precipitation in southern Wisconsin is about 4 to 4.25 inches.

August 23 and August 24, 2006

A stagnant weather pattern on August 23rd and 24th resulted in waves of heavy rain and severe thunderstorms. A warm front pushed north during the afternoon of August 23rd. A very unstable airmass with moderate shear caused thunderstorms to break out during the afternoon and continue through most of the overnight as a warm front moved north through the area. After a brief respite of only 3 hours during the morning hours of August 24th, more storms developed during the late morning and afternoon hours. More heavy rain, large hail, damaging winds, and vivid lightning resulted from these storms. Urban flooding in Dane and Kenosha counties caused a few hundred thousand dollars in structural damage. Some two-day rainfall totals across Dane County include 5.70 inches in Oregon, 5.38 inches in Cottage Grove, 3.26 inches in Middleton, 2.77 inches at Beloit College, and 2.73 inches at Madison Truax Field. Roughly 12,000 customers lost electrical power due to downed power lines and lightning strikes.

July 27, 2006

A 1-in-a-100-year flash flood occurred from the west side of Madison to around the Capitol Square after 3 to 5 inches of rain fell within a 90 minute timeframe. There were no reports of injuries or deaths. The heavy rain resulted from slow-moving and back-building thunderstorms that essentially remained nearly stationary over the city of Madison. The hilly terrain and a typical urban setting of a lot of concrete and asphalt enable the runoff water to quickly overwhelm the storm sewers and concentrate water in low-lying areas of the city. Water depths reach to the top of small vehicles - 4 to 5 feet deep in spots. Many roads became impassable due to the flood waters, and many residential homes and businesses on or near the UW-Madison campus had flooded basement and first-floor flooding. Some basement apartment units had water depths of 6 to 8 feet. Nearly all campus buildings had flooding of varying degrees of intensity, and the Camp Randall football field sustained damage. Some campus buildings had flat roofs that quickly flooded as storm drains became plugged, which allowed water to run through the walls and ceilings of buildings. The buildings that sustained the most damage were the Memorial Union, Computer Sciences, and Veterinary Medicine. Numerous vehicles on or near the campus were damaged or totaled by the flood waters, and some were reported to be floating away. Unofficial rain gages measured 4.5 to 5 inches from just west of West High School up to the Capitol Square. WSR-88D Doppler rainfall estimates were in the 3 to 5 inch rain, therefore it appears the unofficial rain gages were very accurate. Rainfall amounts quickly fell off to 1 to 1.5 inches near the south Beltline. It is nearly impossible to assess the monetary value of the flash flood damage.


June 9-12, 2004

Scattered, widespread heavy rains across south-central and southeast Wisconsin during this period kept many rivers and streams at or above flood stage for most of the month. Monthly rainfall totals generally ranged from 4 to 7 inches across south-central and southeast Wisconsin. During this time, high water levels submerged most of the bottom-level land near rivers and streams; closed some major state highways; forced water into basements; damaged corn, soy bean, and alfalfa crops; delayed planting of entire fields; washed out gravel road shoulders; and damaged foundations of homes and businesses. In general, the flooding was the worst since 1993 on a widespread basis and locally in the past 25 to 30 years. Federal Disaster Declaration 1526 covered all 20 counties in south-central and southeast Wisconsin for storms, tornadoes, and flooding for the period of May 19-July 3, 2004. All counties qualified for "individual assistance". In Dane County, lake levels were 1 to 3 feet above normal. Minor basement flood damage to 127 homes, and major damage to 3 homes, was reported and property damages were estimated at $1 million. Estimated crop losses were $3million.

2001

2001 started very dry, beginning in the fall of 2000, with all regions of the state below 50 percent of the October precipitation average. Beginning in the winter, precipitation was highly variable and the state went through a series of wet and dry spells. However, by May the central and southern portions of the state had received 160 percent of normal precipitation. After a July dry spell, severe thunderstorms on August 1-2 dumped heavy rain over a large portion of Dane County. Most areas of the County received between 2 and 5 inches of rain. The heaviest rainfall was centered over the northwest portion of Dane County. A credible report to the National Weather Service indicated that an 11-inch capacity rain gage had overflowed in the Village of Black Earth. Flash flooding occurred in the Black Earth Creek with significant impact to the Villages of Black Earth and Mazomanie. Flash flooding also occurred in Roxbury Creek, causing a significant impact on the village area in the Town of Roxbury.

2000

The month of May 2000 was a particularly wet month in the southern half of the state. Data from the National Weather Service indicates that it was the wettest May ever recorded for most locations in southern Wisconsin, including Dane County. Generally, 8 to 12 inches of precipitation was measured, with some locations in Dane and Iowa Counties unofficially receiving between 16 and 18 inches. Normal rainfall for May is 3.14 inches. Finally, the wet rainy weather culminated in a series of severe thunderstorms and heavy rains that began on May 26 and continued into early June. Those storms dumped nearly 6 inches of rain on already saturated soils. This caused most, if not all of the rainfall to run off instead of infiltrating into the ground. The result pushed most area rivers over flood stage, raised all of the Yahara Lakes to record or near record levels, and caused severe, widespread flooding. Dane County received a presidential disaster declaration and was eligible for public and private assistance programs.

1996

The County experienced widespread flooding in 1996, largely as a result of a June 16-18 storm. Over this period of time, heavy rains fell over most of the region of southern Wisconsin. The National Weather Service recorded 5.25 inches of rain in Madison. The Sun Prairie Wastewater Treatment Plant recorded 5.77 inches over this same time period. Lake


levels of the Yahara Chain of Lakes were within inches of all-time record highs and most rivers and streams were at or above flood stage. The flooding that resulted caused severe problems on agricultural lands as well as in the City of Madison, the City of Monona, the City of Sun Prairie, the Villages of Mazomanie and Black Earth. In the Department of Emergency Management’s damage assessment, nearly every local unit of government in the County reported at least some damage to public and private facilities.

1993

Flooding was also widespread across the County in 1993. The flooding in 1993 was a result of above average precipitation for each month from March through August, as recorded by the National Weather Service. The primary significance of the 1993 storm events was not the intensity, but the frequency. Most days during June and July had at least a minor rainfall event. Between June 28 and July 11, there were only two days out of 14 with no rain. There was also one significant individual storm during this time period, a 3.75-inch rainfall event on July 5, 1993. This was approximately a 5- to 10-year storm (10 percent to 20 percent annual probability) event. The total precipitation for this 14-day period was 7.86 inches while the average is 1.83 inches. Therefore, during most of June and July, the soils of the County remained saturated and did not have time to dry out between storms. This caused significant crop loss, and the resulting increased runoff raised most area rivers over flood stage and raised all of the Yahara Lakes to record or near record levels. Dane County received a presidential disaster declaration and was eligible for public and private assistance programs.

July 1990

Torrential rains and flooding caused an estimated $14 ($18.4) million in damages in 14 counties in southern Wisconsin. In the City of Madison, 12 trees were lost due to high winds, storm sewers backed up, and two homes caught fire due to lightning strikes, one sustaining $50,000 ($65,800) in damages. Several parts of the Military Ridge bicycle and hiking trail were washed out. Also, high water lifted a car off the ground on University Avenue and washed it across a parking lot. Businesses dependent upon water-based recreation lost money having to cancel boat trip due to high waters in rivers.

Summer 1980

Heavy rains drenched central Wisconsin and Dane County. August rainfall broke the month’s record, setting the bar at 9.49 inches. The National Weather Service issued numerous flash flood warnings. Madison Gas and Electric reported 15 power outages. Two hundred people were affected on Madison’s west side and another 200 were affected in the Springfield area. At the same time, more than 2 inches of rain fell in Mount Horeb. Lake Mendota rose 17.5 inches above the normal of 850 feet above sea level. Lake Monona was also above the seasonal average. Media outlets designated southern Wisconsin including Dane County as “rain alley.”

July 1978

Former President Jimmy Carter declared a flooding disaster for 16 southern and western Wisconsin counties—Dane included. In July, Wisconsin experienced rainfall that was 75 percent above normal. An estimated $53 ($139.8) million in damage was produced from a series of weekend storms July 8-9. Rain fell heavily throughout the state from May through September, producing a bumper crop for some farmers, but other farmers were not so lucky. In Dane County, about 9,000 acres of cropland on 800 farms were damaged in June


and early July rains. Crop losses approached $2.1 ($5.5) million on 500 farms; corn and soybean crops were most severely damaged suffering $1.4 ($3.7) million in losses. Tobacco and cabbage losses were estimated at $700,000 ($1.8 million). Floodwater also eroded soil from fields and scattered debris, increasing costs to farmers. Residents in the City of Monona along Lake Monona also flooded.

1973

Flooding again comes to the Mississippi river as Wisconsin is declared a disaster area as one of 8 states that split $147 ($570) million in Federal aid. Then-governor Lucey estimated private and public damage at almost $2.3 ($8.9) million. Madison broke a 17-year-old, 24-hour rainfall record as streets and sewers flooded. The City of Madison received 25 calls for flooded basements. The hardest hit areas in Madison on the east side included East Washington, and Milwaukee St., on the west side Odana Hills, Crestwood, Meadowood, Park St., and Manitou Way. Streetlights shorted, auto accidents were reported. Rain and debris frustrated street crews. Monona police reported flooding in Maywood Park and stalled motorists on Lake Monona shoreline streets. The federal government began offering funding for repairs due to flooding, but only to those units of government with a flood plain ordinance. Dane County and most incorporated areas did not comply with Federal regulations.

1960

In 1960, citizens in Dane County were complaining about flooding in Starkweather Creek northeast of Madison, as well as the creek’s resident insects and putrid odor. Additionally, basements were flooding and sewers were backing-up in the area and there were calls for dredging of the Creek.15

High Lake Levels

The Yahara Chain of Lakes runs directly through the most urbanized areas of the County. Flooding occurs in low areas surrounding many of the lakes when lake levels rise. Survey data collected indicated that lakeshore flooding is a significant problem, especially in the Yahara River and Lake Monona watershed. High lake levels in the Yahara Chain of Lakes during and after major storms events has affected hundreds of homes, flooding basements or first floors and damaging unimproved property. Total damages to residences along the lakes were by far the highest reported. Historical data shows that the lake levels are becoming more volatile. The lakes were at record or near record high levels for all three of the major flooding events of the past decade. Record levels were set in 1993, broken in 1996, and then broken again in 2000. Table 4.10 indicates the levels of the lakes with respect to the base flood elevations shown in FEMA’s Flood Insurance Rate Maps for Dane County.

15 Dane County Department of Emergency Management “Dane County Flood Mitigation Plan 2004” p 31.


Table 4.10 Lake Levels in Peak Flood Years

Lake Base Flood Elevation

Pre-1990 Peak

Elevation 1993 Peak Elevation

1996 Peak Elevation

2000 Peak Elevation

2007 Peak Elevation

2008 Peak Elevation

Mendota 852 851.5 (Set in 1978) 852.25 851.46 852.74* 851.80 851.99

Monona 848 847.2 (Set in 929) 847.13 847.26 847.48* 847.46 847.86

Waubesa 847 Unknown 846.69 846.72* 847.05 846.94 847.07

Kegonsa 845 Unknown 844.84 845.35* 845.04 844.07 845.72 * Record high level Source: Dane County Public Works, 2009 FEMA Flood Insurance Rate Maps, Wisconsin State Journal; Source of 2007-08 data is Dane County Land and Water Resources Department lake levels website.

The data shown in Table 4.10 highlights an interesting element of the flooding in Dane County. It doesn’t take a 100-year rainfall event for the Yahara Lakes to reach the mapped 100-year flood levels. For Dane County, a 100-year rainfall event is defined as 6 inches of rain falling over 24-hours. Peak rainfalls in a single day approached this level in 1996, but the rainfall was much more spread out in the other flood years. Yet in all of these years, the lake levels for all four lakes were very near or above the base flood elevation. This helps to underscore the fact that 100-year rainfall events are different from 100-year flood events. From the perspective of lake level response to storm events, circumstances such as soil saturation and frequency and duration of the rainfall events are as significant as or more significant than 24-hour rain intensity.

Flood Insurance Claims

There are approximately 65 properties in Dane County on record as having made flood insurance claims between 1978 and 2002. Between 2002 and 2008, an additional 123 claims have been paid, for a total of $1,699,049 in flood insurance payments. This number represents a small sample of the actual number of homes impacted by flooding in the County. The majority of these properties are located along the Yahara Chain of Lakes (City of Madison, City of Monona), but also the Village of Oregon and Village of Mazomanie, and City of Edgerton has had claims. Table 4.11 provides more detail on the number of paid flood insurance claims in Dane County since 1978. Note that a number of the claims are in the X zone, which is considered to have no or minimal flood potential.

Table 4.11 Paid Flood Insurance Claims

Community Name FLOOD_ZONE POST_FIRM # of CLAIMS Total Payments Black Earth, Village Of A N 2 $4,969Black Earth, Village Of A Y 3 $9,754Black Earth, Village Of X N 1 $262Cross Plains, Village Of X N 1 $1,724Dane County A N 30 $836,017Dane County OTH 1 $7,023Dane County X N 15 $419,566Dane County X Y 7 $62,496De Forest, Village Of X N 1 $7,258De Forest, Village Of X Y 3 $13,051


Community Name FLOOD_ZONE POST_FIRM # of CLAIMS Total Payments Edgerton, City Of A N 5 $67,102Edgerton, City Of OTH N 2 $3,103Edgerton, City Of X N 1 $8,077Madison, City Of A N 3 $9,100Madison, City Of OTH 1 $649Madison, City Of X N 9 $46,962Madison, City Of X Y 2 $16,066Marshall, Village Of OTH 1 $222Marshall, Village Of X Y 1 $15,351Mazomanie, Village Of A N 6 $10,830Mazomanie, Village Of X N 2 $401Monona, City Of A N 4 $25,002Monona, City Of X N 7 $43,229Oregon, Village Of A N 15 $163,376Oregon, Village Of A Y 1 $26,221Oregon, Village Of OTH 1 $6,894Oregon, Village Of X N 3 $9,798Sun Prairie, City Of X N 1 $2,964Waunakee, Village Of X Y 2 $34,220 TOTAL 131 $1,851,689

Source: FEMA; Data as of end of year 2008


The studies used to generate the Flood Insurance Rate Maps are based on calculations of the probability of future flooding. Flood studies use data and modeling, as well as historical records to determine the potential for floods of a certain magnitude to occur. Such events are measured by their recurrence interval, e.g., a 25-year flood or a 100-year flood. These terms can be misleading. People often interpret the 100-year flood to mean once every 100 years. This is not correct. The 100-year flood is actually a statistical term that refers to the odds of a flood of that size happening in any given year. This converts to a probability of 1 percent that a flood of this magnitude will occur. A 100-year flood could occur twice in the same year, two years in a row, or four times in 20 years. A 500-year flood has a 0.2 percent probability of occurrence any given year. Smaller, less extensive and less damaging events happen more frequently, but even 100-year events can occur in back-to-back years. Based on the National Weather Service’s records of 27 damaging flood events in the 1982-2008 time period, or 27 years, a flood occurs somewhere in Dane County on average every year and thus warrants a highly likely occurrence rating. Flooding that merits a presidential disaster declaration (7 events between 971-2008) occurs every 5 years on average in the County.

Impact Assessment

Because of the varied nature and widespread damage floods cause, this profile is not discussed in terms of direct and indirect potential impacts. Instead, each area that flooding impacts is broken down and explained, including an analysis of both direct and indirect


impacts thereof. The impacts of flooding in Dane County are far ranging. Specific examples of how floods negatively impact Dane County are summarized below:

• Floods cause damage to private property that often creates financial hardship for individuals and families;

• Floods cause damage to public infrastructure resulting in increased public expenditures and demand for tax dollars;

• Floods cause loss of personal income for agricultural producers that experience flood damages;

• Floods cause loss of income to businesses relying on recreational uses of County waterways;

• Floods cause emotional distress on individuals and families; • Floods can cause injury and death.

Health and Safety

There is very little available data on health problems caused by flooding in Dane County because data collection mechanisms are varied, particularly in terms of reported occurrences versus actual occurrences. The first impact comes from the water itself and is considered the direct impact of flooding. Floodwaters carry whatever was on the ground that the upstream runoff picked up, including dirt, oil, animal waste, and lawn, farm and industrial chemicals. Pastures and areas where cattle and hogs are kept can contribute polluted waters to the receiving streams.

Floodwaters saturate the ground, which can lead to infiltration into sanitary sewer lines. When wastewater treatment plants exceed capacity, there is nowhere for the sewage to flow. Infiltration and lack of treatment lead to overloaded sewer lines that can back up into low lying areas and homes. Even though diluted by floodwaters, raw sewage can be a breeding ground for bacteria, such as E.coli, and other disease causing agents.

The second set of health concerns occur after the water is gone, and are considered indirect impacts of flooding. Stagnant pools become breeding grounds for mosquitoes, and wet areas of a building that have not been cleaned breed mold and mildew. A building that is not thoroughly and properly cleaned becomes a health hazard, especially for small children and the elderly. Another health hazard occurs when heating ducts in a forced-air system are not properly cleaned after inundation. When the furnace or air conditioner is turned on, the sediments left in the ducts are circulated throughout the building and breathed by the occupants.

Finally, flooding creates long-term psychological impacts on victims. The cost and labor needed to repair a flood-damaged home puts a severe strain on people, especially the unprepared and uninsured. There is also a long-term problem for those who know that their homes can be flooded again. The resulting stress on floodplain residents takes its toll in the form of aggravated physical and mental health problems. This is also considered an indirect impact of flooding.

Building Damage

In terms of numbers of people affected and total economic losses, damage to buildings, especially residences is usually the County’s largest single flood problem. Due to the relatively shallow flood depths, soaking causes the most common type of damage inflicted by a flood. When soaked, many materials change their composition or shape. Wet wood will swell and, if dried too quickly, will crack, split or warp. Plywood can break apart. Gypsum


drywall will fall apart if it is bumped before it dries out. The longer these materials are wet, the more moisture, sediment and pollutants they will absorb. Walls present a special problem: a “wicking” effect pulls water up through wood and wallboard, soaking materials several feet above the actual high-water line. Structural damage to buildings has not been a common problem in Dane County.

Soaking can also cause extensive damage to household and other building contents. Wooden furniture may become so badly warped that it cannot be used. Other furnishings such as upholstery, carpeting, mattresses, and books usually are not worth drying out and restoring. Electrical appliances and gasoline engines will not work safely until they are professionally dried and cleaned. In short, while a building may look sound and unharmed after a flood, the waters can cause a lot of damage. To properly clean a flooded building, the walls and floors should be stripped, cleaned, and allowed to dry before being recovered. This is expensive and can take weeks.

Sewer and Wastewater

Sewer and wastewater service and infrastructure are compromised during flooding events in many locations around the County with consequences for homes as shown in Figure 4.10. Sewer backups in residential basements are the primary result of overtaxed wastewater systems. Survey respondents reported 100’s of residences that have had sewer backup problems. During major storm events, flows to the treatment plants increase, and in some cases triple due to water infiltration into the piping system. Failing pumps, and inflow meter damage, are also a problem. Additionally, flooded roads inhibit the timely repair of pumping stations.

Figure 4.10 Number of problemsheds in each watershed impacted by sewer back-ups.

Sewer Backups

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Source: 2003 flood mitigation planning survey

Commercial Flooding

Flooding of commercial structures is not a significant problem in Dane County as shown in Figure 4.11. Outside the metropolitan area, surveys completed documented only very few


occurrences of any damage of this type. The majority of commercial flooding occurs on the isthmus between Lake Mendota and Lake Monona, a densely urbanized area, which was historically wetland.

Figure 4.11 Number of Impacted Commercial Structures in Each Watershed

Commercial Flooding

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Source: 2003 flood mitigation planning survey.

Road, Shoulder, and Ditch Flooding

Forty percent of problemsheds reported by survey respondents included flooding on roadways. A possible contributing factor is under-sized culverts that become damaged during high water flows. Very few bridges have been damaged though they may play a role in constricting water flows. This flooding, and often-associated road or ditch damage, inhibits emergency vehicle movement and could compromise public safety.


Figure 4.12 Number of problemsheds in each watershed that have been impacted by road, ditch or culvert damage

Road/Culvert Flooding

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Source: 2003 flood mitigation planning survey

Farmland Flooding

Dane County is the one of the most fertile counties in the state of Wisconsin, and as a result farming plays a major role in the local economy. Flooding of farm fields and crop loss is an additional stress on an already highly stressed profession. The amount of crop loss in the County per acre varies across the landscape depending upon the topography—generally the more flat the land the more pervasive the problem. The east side of the County experiences relatively severe crop losses on occasion; the west side of the County, though not without this impact, is less affected. Crop loss is capricious—timing of storms, duration of standing water, and type of crops play a part. Prolonged flooding occurring while crops are immature can lead to total crop loss for a year. Corn, for instance, has difficulty withstanding flooded soil. Flooding of short duration or later in the growing season may have little or no effect on the harvest.

Floods have caused crop losses throughout the County. Figure 4.13 shows that the most heavily affected area is the Upper Koshkonong watershed. Total acres affected by flooding reported through the 2003 survey approaches 5,500 acres and losses are in the 10’s of millions of dollars over 1993-2003. The owners of approximately 55 different parcels of land have filed for flood insurance claims countywide.


Figure 4.13 Number of Acres of Agricultural Land in Each Watershed that Have Been Impacted by Severe Flooding

Farmland Flooding

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Erosion and Stream Pollution

Due to the agricultural character of rural Dane County, erosion is a concern. Ditches that once conveyed water quickly have become laden with soil, decreasing their capacity to convey water. Construction sites also contribute to siltation in streams. Siltation and trash also compromise stream quality.

Ongoing and successful stream restoration projects, and the depositing of organic materials in streams, increase woody matter in stream channels. The buildup of organic material slows water flows. Woody material builds up along the buttresses of bridges and other human-made obstructions in the river channels and alongside river channels themselves. While the slowing of water may be beneficial for downstream residents, areas where the build-ups occur increase the risk of flooding.


Due to the wide variety and severity of the impacts that flooding can have in Dane County an overall critical impact magnitude and severity rating is appropriate.



Population

Vulnerable populations in Dane County include residents living in known flooding areas or near areas vulnerable to flash floods. Special population include the students at the University of Wisconsin at Madison, those living in long-term care facilities, mobile homes, hospitals, and temporary shelters, people who speak English poorly, tourists and visitors, the elderly and very young, and those with developmental, physical or sensory disabilities. These populations may be more vulnerable to flooding because of limitations on movement, fiscal income, challenges in receiving and understanding warnings, or unfamiliarity with surroundings.

As part of this plan’s 2009 update an estimate of the population exposed to flooding was created using a GIS overlay of the 2008 DFIRM on potentially flooded residential parcels. The total number of residential parcels was aggregated by municipality and multiplied by the average household size in Dane County (2.43 persons) to estimate population resident in the 100 year and 500 year flood zones. According to this analysis, 2,474 persons are potentially vulnerable to flooding from the 100-year event, and an additional 936 are vulnerable to the 500-year event. The City of Madison, Village of DeForest, City of Stoughton and Town of Dunn all have more that 200 persons resident in the floodplain. the City of Monona, the villages of Cross Plains and Mazomanie and towns of Westport, Pleasant Springs, Albion and Mazomanie have between 100-146 persons in the 100 year floodplain. The HAZUS-MH analysis performed for the State Mitigation Plan update in 2008 estimates that 4,340 households would be displaced by 100-year floods, and that 8,107 would seek temporary shelter in public shelter. The HAZUS methodology is more general and likely overestimates the population vulnerability.

Table 4.12 Floodprone Population Estimate

Jurisdiction Population Est. 100-yr Flood Zone

Population Est. Flood Zone X500

Total Population Estimate

City of Madison 289 168 457

City of Middleton 10 68 78

City of Monona 146 19 165

City of Stoughton 250 - 250

City of Sun Prairie 15 2 17

City of Verona 61 - 61

Village of Belleville 5 27 32

Village of Black Earth 36 53 90

Village of Cambridge 17 2 19

Village of Cottage Grove 2 - 2

Village of Cross Plains 100 12 112

Village of DeForest 258 75 333

Village of Marshall 61 63 124

Village of Mazomanie 143 112 255

Village of McFarland 49 39 87

Village of Oregon 53 7 61


Jurisdiction Population Est. 100-yr Flood Zone

Population Est. Flood Zone X500

Total Population Estimate

Village of Rockdale 10 2 12

Village of Waunakee 29 49 78

Town of Albion 107 - 107

Town of Berry 5 - 5

Town of Black Earth 7 - 7

Town of Blue Mounds 2 - 2

Town of Bristol 15 - 15

Town of Burke 15 - 15

Town of Christiana 5 5 10

Town of Cottage Grove 17 - 17

Town of Cross Plains 12 - 12

Town of Deerfield 2 - 2

Town of Dunkirk 7 - 7

Town of Dunn 209 - 209

Town of Madison - 124 124

Town of Mazomanie 109 58 168

Town of Medina 5 - 5

Town of Montrose 15 27 41

Town of Oregon 7 - 7

Town of Perry 2 - 2

Town of Pleasant Springs 114 15 129

Town of Roxbury 56 - 56

Town of Rutland 7 - 7

Town of Springdale 2 - 2

Town of Springfield 5 - 5

Town of Sun Prairie 7 - 7

Town of Vermont 5 - 5

Town of Verona 7 - 7

Town of Westport 146 5 151

Town of Windsor 49 2 51

Total 2,474 936 3,409

Historical data yields little information on deaths or injuries by flooding and flash flooding in the County. This is likely due to the slow-rise nature of flooding around lakes and lowlands, giving people adequate time to evacuate. Most flood deaths and injuries are associated with persons who try to drive vehicles into flooded roads and underestimate the depth and velocity of floodwaters.

General Property

Flooding of residential structures in Dane County is a major concern. This type of flooding has several causes: river flooding, high lake levels, sewer backups, stormwater runoff from


urban areas as well as farmland, and high groundwater. Effects include flooded basements and first floor flooding. Combinations of these elements have damaged many structures and put even greater numbers at risk. Table 4.12 demonstrates the number of residents impacted by flooding from the major watersheds and rivers in the Dane County area. Figure 4.15 illustrates the levels of flooded basements for each watershed, and Figure 4.14 displays the number of residences flooded into the first floor.

Figure 4.14 Number of Problemsheds in Each Watershed that Have Been Impacted by First Floor Flooding

First Floor Flooding

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Figure 4.15 Number of Problemsheds in Each Watershed that Have Been Impacted by Flooded Basements.

Basement Flooding

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Repetitive Loss Properties

A “repetitive loss” property is one that has received two or more flood insurance claim payments for at least $1,000 each in any 10 year period since 1978. There are thirteen “repetitive loss” properties in Dane County, which is an increase from the seven identified in 2003. The general locations of these properties are illustrated in Figure 4.16. These properties are important to the National Flood Insurance Program because they account for one-third of national flood insurance claim payments. There are several FEMA programs that encourage communities to identify the causes of their repetitive losses and develop a plan to mitigate the losses. The repetitive loss properties in the County are all residential structures and are scattered around the County, thus there are not many distinct repetitive loss “areas.” There are two located in the City of Monona and three in the Village of Oregon. The Village of Mazomanie, Village of Black Earth, Village of DeForest, City of Madison, Town of Madison, Town of Roxbury, Town of Albion, and Town of Cottage Grove have one each. Addressing the areas where these repetitive losses occur is both a County and national priority.


Figure 4.16 Dane County Repetitive Flood Loss Properties



GIS analysis of flood hazards and recently developed critical facilities databases during the 2009 update of this plan indicate that there are several critical facilities that are potentially exposed to the flood hazard. A summary table of the potentially impacted facilities can be referenced in Section 4.3 Vulnerability Summary. A map of the location of critical facilities within the floodplain is shown in Figure 4.17. Detailed facility information can be referenced in the jurisdictional annexes. 259 structures were identified as within the DFIRM 100-year flood zone. 173 of those structures are manufactured homes, leaving 86 facilities of other types. 36 of the other types are bridges, which may or may not be susceptible to flood damage or inundation. 42 structures were identified as within the DFIRM 500-year flood zone, 19 of which are manufactured homes. An additional 100 structures were identified in flood hazard areas delineated by FEMA’s HAZUS-MH program that are not in a DFIRM flood zone.


Figure 4.17 Critical Facilities Potentially Vulnerable to Flooding



Natural resources are generally resistant to flooding except where natural landscapes and soil compositions have been altered for human development or after periods of previous disasters such as drought and fire. Wetlands, for example, exist because of natural flooding incidents. Areas that are no longer wetlands may suffer from oversaturation of water, as will areas that are particularly impacted by drought. Areas recently suffering from wildfire damage may erode because of flooding, which can permanently alter an ecological system.

Vulnerable cultural resources include the University of Wisconsin campus located in downtown Madison. GIS analysis of flood hazards and historic structure databases during the 2009 update of this plan indicate that there are eight historic properties that are potentially vulnerable to flooding (5 in the 100-yr, 2 in the 500-yr, and 1 in a HAZUS only flood area). No further detail on the historic structures was available.



Given the interplay of the contributing influences, the potential exists for flood damages to continue to rise. While the potential for future damages is difficult to calculate accurately, there are indicators and acceptable methods for estimating future losses.

Residential Losses

The Federal Emergency Management Agency recommends a methodology of estimating future losses based on an inventory of buildings and structures that lie within the flood hazard boundary of the 100-year flood event. Table 4.13 provides an estimate of the extent of damage from various flood depths on different types of structures. This table is from FEMA’s cost-benefit analysis module and has been compiled based on flood damage data from across the country. To utilize this table, the approximate elevations of both the building first floor and the water level during the 100-year flood are needed. From the 100-year flood elevation, subtract the first floor elevation of the building. This figure then can be used to estimate the extent of damage to the type of building that was flooded. For example, if the 100-year flood event elevation is approximately 848 feet above mean sea level and a one story home assessed at $112,000 has a first floor elevation of 844 feet, it is estimated that this four feet of flooding would cause 28 percent or $31,360 in damage to the building.

Table 4.13 Estimation of Damage to Structures

First Floor Flood Depth (Feet)

One Story No Basement (% of Building

Damaged)

Two Story No Basement (% of Building

Damaged)

One or Two Story with Basement

(% of Building Damaged)

Manufactured Home (% of Building

Damaged)

-2 0 0 4 0

-1 0 0 8 0

0 9 5 11 8

1 14 9 15 44

2 22 13 20 63

3 27 18 23 73


First Floor Flood Depth (Feet)


Damaged)


Damaged)

One or Two Story with Basement

(% of Building Damaged)

Manufactured Home (% of Building

Damaged)

4 29 20 28 78

5 30 22 33 80

6 40 24 38 81

7 43 26 44 82

8 44 29 49 82

>8 45 33 51 82 Source: Federal Emergency Management Agency. Estimation of damage potential to buildings based on flood depth relative to the first floor of the building. The negative numbers in the First Floor Flood Depth column indicate flood levels that are lower than the first floor of the building. The resulting flood damage potential is expressed as a percentage of the assessed value of the building.

Flooding also causes damages to the contents of buildings that are flooded. Table 4.14 provides a method for estimating the damage potential to building contents. Contents damage includes damage to furniture, appliances, clothing, and other incidental items not included in the building value.

Table 4.14 Estimation of Damage to Building Contents

First Floor Flood Depth

(Feet)


Damaged)


Damaged)

One or Two Story with Basement (% of Building

Damaged)

Manufactured Home(% of Building

Damaged)

-2 0 0 6 0

-1 0 0 12 0

0 13.5 7.5 16.5 12

1 21 13.5 22.5 66

2 33 19.5 30 90

3 40.5 27 34.5 90

4 43.5 30 42 90

5 45 33 49.5 90

6 60 36 57 90

7 64.5 39 66 90

8 66 43.5 73.5 90

>8 67.5 49.5 76.5 90 Source: Federal Emergency Management Agency. Estimation of damage potential to building contents based on flood depth relative to the first floor of the building. The negative numbers in the First Floor Flood Depth column indicate flood levels that are lower than the first floor of the building. The resulting flood damage potential is expressed as a percentage of the total value of the building contents.

During the 2003 development of the Flood Mitigation Plan a detailed flood loss assessment for Dane County was estimated by using a comparison of a digital version of FEMA’s Flood Insurance Rate Maps, Dane County parcel data, and the single and two family residence inventory conducted in 2000 by the Capital Area Regional Planning Commission. While it took a detailed approach, including a method of estimating first finished flood elevations based on GIS-based 2-ft contours, it was limited to the available data at the time and did


not estimate losses for several structures located in A zones. The results of that assessment were summarized by watershed.

During the 2009 update improvements to flood hazard data and inventory data were used to develop a comprehensive flood risk assessment. This included an analysis of all property types that are potentially within mapped floodplains, aggregated by jurisdiction. The County’s 2008 DFIRM was used as the primary flood hazard layer. In addition to the DFIRM, a flood hazard polygon and depth grid was available that was produced during a countywide flood risk analysis using FEMA’s HAZUS-MH. This was developed during the update to the Wisconsin State Hazard Mitigation Plan. Though the flood hazard areas delineated by this program may not be as accurate as the DFIRM, in most areas they are consistent. The advantage to the HAZUS-MH depth grid is that the depth of flooding can be visualized and analyzed, communicating how the risk varies with flood depth. The flood depth was analyzed by jurisdiction, represented in Table 4.14. The average flood depth for the county is 2.5 ft. To create a comprehensive flood hazard layer, the DFIRM and HAZUS-MH flood polygon layers were merged.

The County parcel layer, with 2008 assessed valuations data linked to it, was used as the inventory basis. This was used instead of a structure footprint layer, which was not complete in some urban areas of the County. This layer was intersected with land use and municipal boundary GIS layers so those attributes could be used for aggregation and analysis purposes. Using GIS analysis, parcels that intersected the flood hazard layer and that had an improved value greater than zero were selected. This parcel layer was converted to “centroids” or points that represent the center of a parcel. Those parcels whose center was not within a flood hazard zone were removed from the analysis. Those with their center within the flood hazard layer were assumed to be potentially flood prone. The improved value was assumed to be the structure value, and the contents value was estimated at 50 percent of the improved value.

Using the 2 ft flood as the average depth and assuming a one or two story building with basement, a depth-damage ratio of 20 percent was applied to the exposed structure and estimated content value to develop the loss estimate. While there are limitations to this assessment, and in certain ways it is not as detailed as the 2003 assessment, it does provide a consistent method to estimate loss. The overall loss estimate to the County is shown in Table 4.15 by general land use. Over 1,600 improved parcels are potentially at risk, the majority of them residential. Flood loss totals could exceed $105 million. Note that this analysis does not account for property that may have been elevated to or above the 100-year floodplain, thus it assumes no mitigation in place. This analysis does not capture flood losses in areas outside of mapped floodplains, which is known to be a problem in the County, thus it may actually underestimate the potential losses. According to the HAZUS-MH flood loss done for the State Hazard Mitigation Plan, total losses from flooding are estimated at $460 million. HAZUS-MH inventory data is more generalized that the analysis presented below, but it also accounts for relocation costs, lost wages, and rental income losses, which are not accounted for in this analysis.

Table 4.15 County Flood Loss Estimate Summary DFIRM 100 Year Flood

Property Type Improved

Parcel Count

Improved Values Contents Value

Total Values (Content & Imp.)

Estimated Loss

Residential 1,018 $184,289,200 $92,144,600 $276,433,800 $55,286,760

Other 361 $80,220,600 $40,110,300 $120,330,900 $24,066,180



Parcel Count

Improved Values Contents Value

Total Values (Content & Imp.)

Estimated Loss

Agriculture 192 $28,228,300 $14,114,150 $42,342,450 $8,468,490

Commercial Services 31 $24,640,200 $12,320,100 $36,960,300 $7,392,060

Industrial 15 $15,104,900 $7,552,450 $22,657,350 $4,531,470

Commercial Sales 20 $14,237,200 $7,118,600 $21,355,800 $4,271,160

Transportation 5 $3,283,200 $1,641,600 $4,924,800 $984,960

Institutional/Government 3 $1,483,300 $741,650 $2,224,950 $444,990

Total 1,645 $351,486,900 $175,743,450 $527,230,350 $105,446,070

In addition to the 100-year event, the additional damage from a 500-year flood was analyzed. Table 4.16 shows the summary of property types that are located within a 500-year flood zone, according to the 2008 DFIRM. The table indicates an additional $252 million in property is exposed to this hazard and could result in another $50 million in losses.

Table 4.16 County Flood Loss Estimate Summary DFIRM 500 Year Flood


Parcel Count

Improved Values Contents Value Total Values

(Content & Imp.) Estimated

Loss

Residential 385 $51,731,600 $25,865,800 $77,597,400 $15,519,480

Other 43 $26,119,300 $13,059,650 $39,178,950 $7,835,790


Commercial Services 29 $43,651,800 $21,825,900 $65,477,700 $13,095,540

Industrial 26 $25,426,300 $12,713,150 $38,139,450 $7,627,890

Recreation 23 $5,743,900 $2,871,950 $8,615,850 $1,723,170

Total 541 $168,099,200 $84,049,600 $252,148,800 $50,429,760

The 2008 DFIRM data also allowed an analysis of properties located in the floodway, or zone of 100-year flooding that is anticipated to have the greatest depths and velocities. Table 4.17 is a summary of these properties, which could be considered a priority for mitigation. According to this analysis Deforest, Cross Plains, Verona, Cottage Grove, Black Earth, Mazomanie have the highest concentrations of properties in the floodway.

Table 4.17 County Summary of Floodway Properties

Property Type Improved Parcel Count Improved Values Contents Value Total Values

(Content & Imp.) Estimated Loss

Residential 152 $22,903,600 $11,451,800 $34,355,400 $6,871,080

Other 67 $14,517,900 $7,258,950 $21,776,850 $4,355,370

Agriculture 26 $4,390,000 $2,195,000 $6,585,000 $1,317,000



Property Type Improved Parcel Count Improved Values Contents Value Total Values

(Content & Imp.) Estimated Loss

Commercial Services 4 $2,852,600 $1,426,300 $4,278,900 $855,780

Industrial 4 $860,400 $430,200 $1,290,600 $258,120

Total 258 $49,122,900 $24,561,450 $73,684,350 $14,736,870

A summary of the loss by jurisdiction is provided in Table 4.18, sorted by number of improved parcels in the floodplain. Note that the highest count of floodprone parcels does not necessarily indicated the highest flood losses, since the loss is dependent on the value of the exposed property. According to this analysis the Town of Dunn, City of Madison, City of Stoughton and Village of Deforest have more than 100 developed properties within the floodplain. The City of Middleton, City of Madison, City of Stoughton and City of Monona have the potential for the highest dollar losses. A countywide map with the locations of these developed, potentially flood-prone parcels, is shown in Figure 4.17. More detailed maps and tables are included in the jurisdictional annexes.

Table 4.18 100-Year Flood Loss Summary by Jurisdiction

Jurisdiction Avg

Depth of flood (ft)

Improved Parcel Count

Improved Values Content Total Values


Loss

City of Fitchburg Total 1.30 3 $825,000 $412,500 $1,237,500 $247,500

City of Madison Total 1.14 131 $31,155,300 $15,577,650 $46,732,950 $9,346,590

City of Middleton Total 1.74 26 $44,842,600 $22,421,300 $67,263,900 $13,452,780

City of Monona Total 1.37 72 $26,874,700 $13,437,350 $40,312,050 $8,062,410

City of Stoughton Total 0.71 109 $28,948,800 $14,474,400 $43,423,200 $8,684,640

City of Sun Prairie Total 2.39 7 $1,775,100 $887,550 $2,662,650 $532,530

City of Verona Total 4.18 28 $5,633,900 $2,816,950 $8,450,850 $1,690,170

Village of Belleville Total 0.76 4 $384,000 $192,000 $576,000 $115,200

Village of Black Earth Total 3.28 23 $5,304,200 $2,652,100 $7,956,300 $1,591,260

Village of Cambridge Total 2.53 10 $2,440,300 $1,220,150 $3,660,450 $732,090

Village of Cottage Grove Total 2.33 1 $163,800 $81,900 $245,700 $49,140

Village of Cross Plains Total 3.11 45 $7,395,300 $3,697,650 $11,092,950 $2,218,590

Village of DeForest Total 0.96 115 $21,229,100 $10,614,550 $31,843,650 $6,368,730

Village of Marshall Total 4.66 27 $4,549,500 $2,274,750 $6,824,250 $1,364,850


Jurisdiction Avg

Depth of flood (ft)




Loss

Village of Mazomanie Total 2.39 76 $6,733,200 $3,366,600 $10,099,800 $2,019,960

Village of McFarland Total 1.71 21 $4,144,000 $2,072,000 $6,216,000 $1,243,200

Village of Oregon Total 0.44 28 $4,954,300 $2,477,150 $7,431,450 $1,486,290

Village of Rockdale Total 1.02 4 $489,100 $244,550 $733,650 $146,730

Village of Waunakee Total 0.32 21 $8,886,600 $4,443,300 $13,329,900 $2,665,980

Town of Albion Total 2.90 68 $6,525,700 $3,262,850 $9,788,550 $1,957,710

Town of Berry Total 2.80 16 $1,425,700 $712,850 $2,138,550 $427,710

Town of Black Earth Total 3.21 13 $1,848,400 $924,200 $2,772,600 $554,520

Town of Blooming Grove Total 3.26 3 $597,200 $298,600 $895,800 $179,160

Town of Blue Mounds Total 6.80 9 $1,462,200 $731,100 $2,193,300 $438,660

Town of Bristol Total 2.56 34 $4,082,900 $2,041,450 $6,124,350 $1,224,870

Town of Burke Total 1.74 17 $4,624,700 $2,312,350 $6,937,050 $1,387,410

Town of Christiana Total 2.92 14 $2,082,900 $1,041,450 $3,124,350 $624,870

Town of Cottage Grove Total 3.25 43 $6,507,700 $3,253,850 $9,761,550 $1,952,310

Town of Cross Plains Total 3.93 10 $1,681,200 $840,600 $2,521,800 $504,360

Town of Deerfield Total 7.46 15 $1,649,600 $824,800 $2,474,400 $494,880

Town of Dunkirk Total 2.97 19 $3,109,100 $1,554,550 $4,663,650 $932,730

Town of Dunn Total 1.32 117 $16,637,400 $8,318,700 $24,956,100 $4,991,220

Town of Mazomanie Total 1.58 79 $7,509,500 $3,754,750 $11,264,250 $2,252,850

Town of Medina Total 0.00 23 $4,082,500 $2,041,250 $6,123,750 $1,224,750

Town of Middleton Total 0.87 2 $235,200 $117,600 $352,800 $70,560

Town of Montrose Total 2.12 33 $5,243,300 $2,621,650 $7,864,950 $1,572,990

Town of Oregon Total 3.18 11 $3,184,000 $1,592,000 $4,776,000 $955,200

Town of Perry Total 2.44 7 $550,600 $275,300 $825,900 $165,180

Town of Pleasant Springs Total 0.35 67 $12,780,100 $6,390,050 $19,170,150 $3,834,030

Town of Primrose Total 4.77 6 $541,500 $270,750 $812,250 $162,450


Jurisdiction Avg

Depth of flood (ft)




Loss

Town of Roxbury Total 0.66 33 $5,132,900 $2,566,450 $7,699,350 $1,539,870

Town of Rutland Total 2.74 18 $3,003,800 $1,501,900 $4,505,700 $901,140

Town of Springdale Total 5.37 23 $5,328,100 $2,664,050 $7,992,150 $1,598,430

Town of Springfield Total 1.70 12 $1,820,800 $910,400 $2,731,200 $546,240

Town of Sun Prairie Total 4.73 24 $3,886,600 $1,943,300 $5,829,900 $1,165,980

Town of Vermont Total 2.80 26 $3,955,200 $1,977,600 $5,932,800 $1,186,560

Town of Verona Total 2.90 22 $4,340,100 $2,170,050 $6,510,150 $1,302,030

Town of Vienna Total 8.08 2 $7,000 $3,500 $10,500 $2,100

Town of Westport Total 3.99 76 $22,003,900 $11,001,950 $33,005,850 $6,601,170

Town of Windsor Total 5.73 40 $7,156,100 $3,578,050 $10,734,150 $2,146,830

Town of York Total 0.99 12 $1,762,200 $881,100 $2,643,300 $528,660

Grand Total 1,645 $351,486,900 $175,743,450 $527,230,350 $105,446,070

2008 Flood Damage Analysis

Dane County Emergency Management requested FEMA Individual Assistance claims data associated with the 2008 flood disaster to supplement the analysis of the flood hazard for this plan. The County geo-located the addresses of those that requested and received Individual Assistance from FEMA, indicating that they were impacted by flooding. 1,627 total claims were able to be geolocated with GIS. This enabled them to be analyzed in relation to other flood hazard layers in GIS, including the DFIRM, HAZUS, and hydric soils layers. In general the claims were in scattered locations around the County. The exceptions were clusters in the Villages of Deforest, Marshall and Sun Prairie and the City of Monona. There is also a significant cluster of claims in the Town of Cottage Grove. Privacy restrictions with the data prevented it from being published in the plan. Interestingly, the majority did not intersect either of the mapped flood hazard areas. The breakdown resulted in the following: • DFIRM 100 year zone: 34 claims • DFIRM 500 year zone: 46 claims • HAZUS (where not coincident with DFIRM): 57 claims • Hydric soils: 158 claims • None of the above: 1,445 claims

This preliminary analysis leads to some initial conclusions:

• Much of the flood risk is outside of mapped floodplains.


• Stormwater drainage issues may be more of an issue than floodplain-related flooding • High groundwater table flooding may be more of an issue than floodplain-related

flooding • Hydric soils areas do contribute to flood problems, but perhaps not as much as initially

believed. • Mitigation and floodplain management is working in Dane County mapped floodplains.

Properties identified in the floodplain with the parcel-DFIRM modeling do not account for elevation or floodproofing that may be in place.

A more detailed analysis of the flood risk in Dane County is needed to refine the flood problems and solutions, or quantify the losses avoided from floodplain management activities. Development Trends

Dane County’s continued population, housing, and employment growth, creates pressure for land use change and the supporting infrastructure improvements. Floodplain management practices implemented through local floodplain management ordinances should mitigate the flood risk to new development in floodplains. The County’s Floodplain development permits are tracked using a paper log that eventually is transferred into a database. This system did not allow an analysis of floodplain development trends during the 2009 update to this plan, as many permits remained to be entered into an electronic log. Urbanization and increasing impervious surface areas tend to increase both the rate and the volume of stormwater runoff. Problems with the regional volume of stormwater runoff remain. Particularly in the case of the Yahara Lakes, it appears that the lakes are acting as a large wet detention basin, holding ever-increasing volumes of stormwater runoff. Thus the largest issue with development trends is urbanization and stormwater drainage issues that add to the volume of floodwaters in floodplains.


Overall, flooding presents a high risk for Dane County. The events occur frequently and have caused damage over significant portions of the county. Although flooding affects residents countywide, based on analysis of past flood events, survey data, and future damage potential estimates, the following areas of the County emerge as areas where there is a likelihood of continued problems in the future.


Figure 4.18 Flood Risk Map


Residential flooding and corresponding losses in the entire Yahara River Basin has been a significant problem in the past. The damage potential for a 100-year flood indicates that the highest monetary loses in the County would be experienced along the Yahara River and Chain of Lakes. Details of the losses estimated for each jurisdiction indicate that the City of Madison, City of Monona, City of Middleton, and Village of De Forest could continue to experience damaging flood events.

• Residential flooding and corresponding losses in the Black Earth Creek Watershed has also been a significant problem in the past. The damage potential analysis indicates that Black Earth Creek Watershed has more buildings located within the mapped floodplain than any other watershed in the County. While the potential monetary losses are not as high as those in the Yahara River Basin, a 100-year flood in the Black Earth Creek Watershed is likely to impact a greater number of people than a similar event in any other individual watershed. These most at-risk communities, including Mazomanie Village and Town, and Black Earth Village and Town, chose not to participate in this plan during the 2009 update.

• Agricultural flooding and corresponding crop loss in the Upper Koshkonong Creek Watershed.

• Residential flooding in the Roxbury Creek Watershed. Areas at risk of future flood losses include the hamlet of Roxbury, Fish Lake, and the floodplain of the Wisconsin River.

• Residential flooding from high groundwater tables in areas of hydric soils and poor drainage.

Table 4.19 provides the summary of how all aspects of the hazard profile were evaluated to establish an overall hazard rating.

Table 4.19 Overall Risk Summary for Flooding

Measurement Rating Value Geographic Extent Significant 3

Probability of Future Occurrence Highly Likely 4

Vulnerability High 3

Magnitude/Severity Critical 3

Overall Risk Rating: High 3.25

4.2.5 Fog

Description

Fog is a cloud made up of water droplets suspended in the air at the earth's surface. Fog forms when air is cooled to its dew point, which is the temperature at which air is saturated with moisture. When air reaches its dew point it condenses into very small particles, forming the tiny water droplets that create clouds. When this occurs very close to the ground, the event is called fog. The intensity and duration of fog varies with the location and type of fog. Severity ranges from early morning ground fog that burns off easily to prolonged valley fog that can last for days. Generally, strong winds prevent fog formation. The following list summarizes several possibilities for the formation, intensity, and duration of fog in the upper Midwest, as compiled in the “Hazardous Weather Resource Guide” by FEMA:


Ground Fog is associated with clear nights, stable air (winds less than 5 mph), and a small-temperature dew point range. It forms when heat radiates away from the ground, cooling the ground and surface air. When air cools to its dew point, fog forms, usually a layer of less than 100-200 feet. It is common in many areas of the United States and generally burns off from the morning sun.

Advection Fog is associated with horizontal wind, warm, humid air, and winter temperatures. It forms when wind pushes warm humid air over the cold ground or water, where it cools to the dew point and forms fog. Advection fog can cover wide areas of the central U.S. in winter. During the winter this is common when snow covers much of the Midwest. The snow cools the bottom portion of the moist air mass often resulting in condensation. This type of fog can be widespread, covering very large areas.

Evaporation Fog is associated with bodies of water. It forms as cold air blows over warmer water, causing the water to evaporate into the cold air, increasing the humidity to the dew point. Vapor condenses, forming a layer of fog 1 to 2 feet thick over the water. It can form over ponds and streams on fall days.

Precipitation Fog is associated with warmer rain and cooler air. It forms when rain evaporates, and the added vapor increases the air to its dew point. The vapor then condenses into fog. Precipitation fog forms on cool, rainy days.

Geographic Extent

Fog may occur anywhere in the county, at any point during the day. Records indicate fog is most likely in the early morning or late evening. Dense fog occurs during every month of the year in Wisconsin. It is more common during the cooler months of September through April. During the fall and spring, fog is more common during the early morning hours and during the winter fog can occur anytime favorable conditions are present. Fog is a semi-regional phenomenon, affecting large portions of the county simultaneously. It may also form in patches, or uniformly across the entire region or county. Based on the available data, fog incidents are expected to cover between 50 and 100 percent of the county, resulting in an extensive geographic extent rating.


The National Weather Service (NWS) and the National Climatic Data Center (NCDC) have been tracking fog and dense fog occurrences since 1999. This information is captured in Table 4.20. Some selected descriptions are compiled below. The majority of these descriptions are also drawn from the NCDC database. Additional sources are cited appropriately.

Table 4.20 Fog/Dense Fog Events in Dane County (1999-2008)

Date Time Type Date Time Type

12/03/1999 04:00 AM Fog 02/20/2002 02:00 AM Fog

12/12/1999 10:00 PM Fog 04/13/2002 01:00 AM Fog

01/09/2000 12:00 AM Fog 03/20/2003 12:00 AM Dense Fog


03/20/2000 09:00 PM Fog 2/26/2004 02:00 AM Dense Fog


Date Time Type Date Time Type


08/24/2000 12:00 AM Fog 10/28/2004 10:00 PM Dense Fog

10/23/2000 10:00 PM Fog 12/9/2004 07:00 PM Dense Fog








06/07/2001 05:30 PM Fog 03/09/2007 05:00 PM Dense Fog





12/16/2001 07:15 PM Fog 02/04/2008 06:00 AM Dense Fog Source: The National Climactic Data Center. Available online at http://www4.ncdc.noaa.gov/cgi-win/wwcgi.dll?wwEvent~Storms last accessed on February 4, 2009.

January 9, 2000

Dense fog with visibilities frequently near or below 1/4 mile blanketed south-central and southeast Wisconsin for about 29 hours, leading to many airline delays or cancellations at area airports. Area newspapers noted dozens of vehicle accidents. South to southeast winds pulled mild air (maximum temperatures in the upper 30s to lower 40s) into southern Wisconsin resulting in considerable snowmelt, while scattered light rain passed overhead. Consequently, there were ample amounts of low-level moisture to initiate the widespread dense fog.

November 15, 2001

Dense fog developed overnight across parts of south-central and southeast Wisconsin, lowering visibilities to near zero to 1/4 mile. The lowest visibilities were found in river valleys west of a line from Madison (Dane Co.) to Beloit (Rock Co). Local airplane traffic was delayed until visibilities improved. Several vehicle accidents were noted in newspapers. In northwest Dane County near Mazomanie on Highway 78, the driver of a vehicle was killed when the vehicle struck a horse standing on the road (fatality indirectly related to fog). Visibility was reported to be about 10 feet around the accident time of about 1:45 a.m. on November 16th. Sixteen children were injured (indirectly related to fog) when a truck struck a Monticello (Green Co.) school bus at 7:46 am on the 16th. Poor visibility was an indirect factor in this accident. The dense fog resulted from the combination of clear skies and light winds after a couple days of rain.


February 20, 2002

Dense fog developed overnight across south central and southeast Wisconsin due to light rain and persistent, on-shore southeast to northeast winds. Visibility was reduced to 1/8 to 1/4 mile, especially in river valleys and other low spots. This led to several vehicle accidents and flight delays or cancellations at airports.

March 20, 2003

Dense fog developed early on March 20th, and dropped visibilities to 1/4 mile or less. Air traffic was delayed or grounded at both Milwaukee's Mitchell Field (Milwaukee Co.), and Dane County Regional Airport. Several school districts delayed school openings by 2 hours, and newspapers reported many vehicle accidents. The dense fog was the result of clear skies, a light south-southeast surface wind, and leftover, low-level moisture

February 26, 2004

Dense fog developed overnight, resulting in visibilities of 1/4 mile or less. Newspaper reports indicated that many icy frost deposits occurred on roads and bridges. Snowmelt due to maximum temperatures in the mid to upper 30s on February 25th contributed the moisture needed to saturate the air as the night progressed. Newspaper reports indicated that some airplane flights were delayed and at least a dozen vehicle accidents occurred.

October 12, 2004

Dense fog developed overnight, reducing visibilities to 1/8 to 1/4 miles. Some school buses were delayed a couple hours, and some airplane traffic was delayed.

December 28, 2005

Dense fog developed overnight over much of south-central and southeast Wisconsin, resulting in the delay or cancellation of some airline flights from Milwaukee Mitchell Field (Milwaukee County). Visibilities fell to 1/8 to 1/4 mile. The dense fog was a result of light southeast winds, a moist low-level atmosphere, and snow-melt.

September 14, 2006

Dense fog developed overnight across parts of south-central and southeast Wisconsin, thanks to clear skies, light winds, and a very moist ground due to recent rains. Visibilities were reduced to zero to 1/4 mile. One person was killed (indirectly-related death) in a vehicle accident southwest of Whitewater and just inside Walworth County. There was another driver killed (indirectly-related death) in a vehicle accident near Madison (Dane Co.). Several airplane flights were delayed or cancelled at Madison's Truax Field and other local airports.

November 20, 2007

A moist, low-level flow ahead of a Dakota low pressure allowed dense fog to develop over Sauk, Washington and Dane Counties. Dew points started off in the 40s but dropped into the 30s as the low pressure moved east along the Wisconsin-Illinois border to southern Lake Michigan. Visibilities dropped to 1/8 to 1/4 mile. Some airplane flights were delayed or cancelled. The media noted a few vehicle accidents. Over the remainder of south-central and southeast Wisconsin visibilities dropped only to 1/2 to 1 mile.


December 19, 2007

Dense freezing fog developed over parts of south-central and southeast Wisconsin and reduced visibilities to 1/8 to 1/4 mile. Untreated road and sidewalk surfaces were coated with thick rime/frost, as well as trees and other cold-surface objects. Newspaper reported indicated that at least a dozen vehicle accidents occurred in each county listed in this event. Moist air moving over a cold, snow-covered terrain initiated the dense freezing fog. Several airline flights were delayed or canceled at Madison Truax Field.

January 6, 200816

Dense fog caused a 100 car pile-up traffic accident which stretched about 5 miles long along Interstate 39/90. There were many injuries, with approximately 54 individuals taken to area hospitals. Two indirect deaths were reported.

February 4, 2008

Widespread dense fog developed after sunset across a good portion of south-central and southeast Wisconsin. Visibilities were reduced to 1/8 to 1/4 mile. The area affected was mostly southeast of a line from Darlington to Madison to Beaver Dam to Sheboygan. Several flights were canceled or delayed at Milwaukee Mitchell Field and other airports. The media noted a few vehicle accidents. Synoptically, diminishing winds, night-time cooling, and a very moist air mass near the ground allowed the dense fog to develop.


The frequencies of past dense fog events provide a base line to predict the risk of future occurrences. Fog events are documented multiple times each year, and there are no climactic indications that these occurrences will change in the measurable future. Based on the past history of events, dense fog has a 100 percent chance of occurrence in a given year, which correlates to a highly likely occurrence rating.

Impact Assessment

Direct Impacts

Direct impacts are rated based on the actual affect of fog on the category being evaluated. The most common direct impact of fog is reduced visibility for motorists. Fog ranges in intensity, duration, and density, with a highly variable onset time. The difficulty in mitigating reduced visibility conditions caused by fog increases the severity of this impact. There is not a readily available source of data to examine the effects of potential impact mitigation, such as street lighting, warning systems, variable speed limit signs, or increased driver awareness programs. It is difficult to quantify the impact of reduced visibility directly. However, the indirect impacts of fog and reduced visibility provide additional insight into the hazard’s impact on Dane County.

Indirect Impacts

Indirect impacts examine those costs which are associated with, but not directly caused by, fog. The increased number of automobile accidents during foggy conditions is an indirect

16 Dane County Local Hazard Mitigation Plan Data Collection Guide, 2009.


impact of fog. The higher damages of automobiles (which are damaged in the increased incidents of motor vehicle accidents) and the associated injury and death rates of the population in these events increase the magnitude of the indirect impacts from this hazard. The specific numbers for these impacts are available in the population and general property subsections of this profile.


The severity of fog events varies. In some cases, accidents attributed to fog may result in multiple fatalities and extensive vehicular property damage, meriting a catastrophic magnitude and severity rating. However, even though these events have a high fatality ratio (determined by the number of killed divided by the number of involved people), the percentage of the population involved in these events is usually minimal. Fog does not prevent facilities and services from operating and does not create undue strain on emergency response capabilities. Therefore, even though fog events may result in tragic situations, the magnitude/severity rating is moderate.


Vulnerability is measured by examining the exposure of four categories to fog: Population, General Property, Essential Infrastructure, and Natural, Cultural or Historic Resources. In general, the greatest exposure to fog is population and general property, both of which are subject to increased incidents of damage (or injury and/or death, in the case of the population) as a result of poor visibility conditions associated with foggy conditions. This is particularly profound when examining traffic statistics. However, this is a small percentage of exposure compared to the overall contents of the County. Fog has a minimal exposure value on essential infrastructures, resources, and other types of general property. The fog itself is not dangerous- the indirect conditions fog creates are. Overall, Dane County has a low vulnerability to fog.

Population

Fog poses the greatest danger to people traveling, particularly on the highways of the County. Dane County’s extensive highway transportation system includes three intersecting interstate highways, major federal and state highways, and County and local roads. These numerous heavily used major thoroughfares in Dane County constitute nearly 3,500 miles of roadway in the County. While people are not directly vulnerable to fog, the hazard greatly increases the danger of driving on the roads. The population is indirectly vulnerable, then, to the accidents and dangerous traveling conditions caused by the fog. Average weekday traffic on the Beltline Highway and Interstate 90 reached a volume of more than 84,000 in 2002. Average weekday traffic on the major arterials outside of the Beltline and I-90 reached a volume of more that 36,000 in 2002. In the 2002-2007 time frame, over 3,000 accidents occurred in Dane County, when fog or smoke was present. Over 1,200 injuries were related to these accidents and 36 people were killed.17 Overall, the population of the county has a medium vulnerability to fog.

17 Wisconsin Department of Transportation “2007 Wisconsin Traffic Crash Facts: Section 2, Crashes.” Available online at http://www.dot.wisconsin.gov/safety/motorist/crashfacts/index.htm last accessed March 3, 2009.


General Property

Vehicles are the most vulnerable aspect of general property, as most accidents during fog are vehicle-to-vehicle. The Dane County Comprehensive Plan (Volume II) reports that Dane County residents own almost 350,000 personal vehicles. Although the number of accidents and deaths are considered indirectly related to the actual weather conditions, they far exceed the number of people killed due to tornadoes or floods for Dane County during this period. These accidents are considered indirectly related because law enforcement officials and the insurance industry assert that most accidents that occur in fog are the result of motorists following too close to the vehicle ahead of them and driving too fast for the weather conditions. The poor visibilities do not allow motorists to adjust when the vehicle in front stops or makes a quick turn.

Fog also increases the vulnerability of those on water, and so boats may also be at a higher vulnerability but there is no data to examine this claim. Some property, such as businesses, homes, utility poles, or other objects located near roadways, may be vulnerable due to vehicle-object crashes impacted by the presence of fog, but there is not a quantifiable way to measure a heightened risk for non-vehicular general property. The overall vulnerability of general property is low.


The most vulnerable aspect of essential infrastructure for the community is the airport. The Dane County Regional Airport (DCRA) in Madison is the second largest airport in the State, providing service to commercial air passenger and cargo carriers, general aviation, and the military. Over 100 daily flights are provided on an average day. In 2006, 1.6 million passengers travel through the DCRA. Records of past incidents report cases of flight delays or cancellations at Dane County Regional Airport due to severe weather and fog. From June 2003 through November 2008, 3.8 percent of all delays into Truax Field were weather related. Nationally, more than 73 percent of all delays are weather-related.18 These figures do not detail when National Aviation System delays are weather related. In 2007, airline delays cost approximately $8,089 million nationwide.19

Generally, hospitals, command centers, fire and police stations, jails, schools, and other examples of essential facilities and infrastructures are not vulnerable to fog. The people employed at these institutions experience the heightened vulnerability discussed in the ‘population’ subsection and emergency vehicles are theoretically subject to the same risks expressed in the ‘general property’ subsection. However, out of 207,756 units involved in accidents in 2007, only 46 involved emergency response vehicles, or less than .03 percent.20 Therefore, the vulnerability of emergency vehicles to traffic accidents is minimal, and the increased vulnerabilities attributed to fog are not measurable. The overall vulnerability of essential infrastructure is medium, due to transportation disruptions.

18 Research and Innovative Technology Administration, Bureau of Transportation Statistics, “Airline On-Time Statistics and Delay Causes” Available online at http://www.transtats.bts.gov/OT_Delay/OT_DelayCause1.asp, last accessed February 4, 2009. 19 Air Transport Association, “Cost of Delays” Available online at http://www.airlines.org/economics/specialtopics/ATC+Delay+Cost.htm, last accessed February 4, 2009. 20 Wisconsin Department of Transportation “2007 Wisconsin Traffic Crash Facts: Section 4, Vehicle Data.” Available online at http://www.dot.wisconsin.gov/safety/motorist/crashfacts/index.htm last accessed February 27, 200



These resources are not vulnerable to fog, excepting those located near roadways, as discussed in the General Property subsection of this profile. The overall impact of fog events on these resources is low.



The vulnerability of motor vehicles to fog is difficult without quantitative data to determine the number of accidents caused by fog relative to all other traffic accidents. According to the 2007 Wisconsin Traffic Crash Facts, 10,255 accidents were reported in Dane County over the year. 46 of these accidents resulted in at least one fatality, while another 3,022 caused injury. Only Milwaukee reported more accidents on a County level. Statewide, 125,123 accidents were reported. 769 of these accidents occurred in fog (or similar condition) with 11 fatal accidents and 255 injury-causing accidents. These accidents were most likely to occur in dark, unlit areas (317). The road conditions were overwhelmingly wet (454). This indicates that 0.61 percent of accidents in Wisconsin are caused by foggy conditions. Applying this percentage to Dane County accidents in 2007, an estimated 62 vehicles were involved in car accidents during foggy conditions.

There is no County-specific data available for the costs and damages of these car crashes, however crash reporting thresholds indicate that these crashes all caused at least $1,000 to “any one person’s property”.21 In addition, cost calculations used in the Crash Facts document assigned values of $1,249,000 for fatal accidents and an average of $32,300 for injury-causing accidents. Applied to the estimated number of accidents in Dane County, fog accounted for approximately $1,909,858 in damages in 2007.22

Economic losses from travel delays, both road and air, could be significant, but the costs and losses from those events is not systematically collected and compiled and thus difficult to estimate. Property, facilities, and natural, historic, and cultural resources are not vulnerable to fog, so their potential loss estimates are minimal.

Development Trends

Populations are considered indirectly vulnerable to fog due to the increased incidents involving traffic accidents; therefore as the population continues to grow, the likelihood of traffic accidents during foggy conditions also increases. Additional development of property will not change the vulnerability rating of the County to fog from a property standpoint. The development of urban areas with fog mitigation technology, including adequate street lighting or variable speed-limit signs, will reduce the exposure of the population and property to indirect impacts of fog. Increased public awareness of appropriate cautions to use in foggy conditions may help prevent an increased vulnerability of the population.

21 Wisconsin Department of Transportation “2007 Wisconsin Traffic Crash Facts: Section 1, General Highlights.” Available online at http://www.dot.wisconsin.gov/safety/motorist/crashfacts/index.htm last accessed February 27, 2009. 22 Wisconsin Department of Transportation “2007 Wisconsin Traffic Crash Facts: Section 2, Crashes.” Available online at http://www.dot.wisconsin.gov/safety/motorist/crashfacts/index.htm last accessed February 27, 200



The overall risk for fog is medium. Fog poses no direct risk to the structures or facilities of Dane County, but contributes to fatal automobile accidents. The indirect impacts of fog are related to increased incidence of traffic accidents and travel delays. As demonstrated in the past history data, the occurrence of fog is common in Dane County. The numbers of auto accidents and flight delays where fog is a factor is available, but the costs and losses from those events is not systematically collected and compiled.

Table 4.21 Overall Risk for Fog







4.2.6 Hail

Hazard Profile

Hail falls from thunderstorm clouds that extend miles high into extremely cold air. Updrafts bring raindrops from the bottom to the top of the cloud where they freeze into ice pellets. The pellets then fall only to be blown back up where another coating of rain freezes to the hailstone and it grows larger, layer by layer. This layering affect increases the size of hailstones, sometimes to the size of baseballs or grapefruits. Typically the stronger the updraft, the more times a hailstone repeats this cycle and consequently, the larger it grows. Once hailstones reach a weight sufficient enough to overcome the updrafts, they fall to the ground. Since the stone is not in the warm air below the thunderstorm long enough to melt before reaching the ground, it falls as ice.

Dane County averages about 3 days with hail per year. The period of time with the most frequent occurrence of hail producing severe thunderstorms is May through September.

Geographic Extent

Hail falls in swaths ranging from 20-115 miles long and 5-30 miles wide, and typically one-half mile wide and five miles long. The swath is rarely a large, continuous bombardment, but generally consists of a series of hail strikes that are produced by individual thunderstorm clouds traversing the same general area. A single storm will produce several series of hail storms as it moves. The swaths may partially overlap but often leave completely undamaged gaps between them.23 Given these facts, the geographic extent rating is significant.

23 Wisconsin Emergency Management. (July 2001). “State of Wisconsin Hazard Mitigation Plan.”


Past History

The National Weather Service and the National Climatic Data Center (NCDC) maintains a listing of reported hail events, with a hail size greater than 0.75 inches, from 1950 through 2008. In Dane County, 111 hailstorms have been recorded since May of 2003. Of those storms, 53 percent created hail of .88” in diameter or larger. 7 incidents produced baseball-sized hail or larger. The largest hail size ever recorded in the County was four inches in diameter in July of 1960.

Hail events historically occur most frequently in June, July, and August, although hail has been reported with thunderstorms in every month of the year statewide. During the summer months there is over a 60 percent chance that a hail event will occur.

July 7, 1991

Dane County received a presidential disaster declaration for damages resulting from a storm on July 7, 1991. Winds topping 80 mph, hail, rain, and lightning caused extensive damage in Dane County. The storm left 60,000 people without electricity and downed so many tree branches that it took weeks for clean up to be completed. Dane County Regional Airport was estimated as receiving $4-5 million in damages losing some planes completely and severely damaging others. Twenty buildings were also damaged at the airport. Local farms sustained $3.1 million in damages to crops and buildings due to hail and high winds. Two people were reported injured in Dane County.

May 18, 2000

A supercell thunderstorm moved east/northeast across Iowa County. Hailstones up to 2.00 inches in diameter pelted and damaged many vehicles and home sidings, while stripping some of the corn and soybean crops. This storm then headed east into Dane County where it unleashed damaging straight-line winds in addition to large hail. Winds were estimated to reach hurricane-force level as the storm tore through Fitchburg where a home's garage was blown over. The storm then hit Madison with powerful winds and golf ball size hail. A Madison home's roof was torn off by the winds, and many large trees were felled. At least 200 vehicles sustained moderate to severe hail damage in Dane County.

August 11, 2002

A cluster of severe thunderstorms blossomed over western Dane County, resulting in wind, hail, and flash flood damage in the Pine Bluff area, west of the Madison metro-area. In the Pine Bluff area, hurricane-force downburst winds reached estimated speeds of 70 kts (80 mph), resulting in toppled trees and power lines. The fringe effects of this powerful macro-burst resulted in some tree damage north to the Cross Plains to Middleton area. The thunderstorm cluster also produced hail up to 2 inches in diameter in the Pine Bluff area, resulting in major damage to at least 100 vehicles, and to roofs and siding of homes.24

April 13, 2006

A cluster of isolated severe thunderstorms hammered Dane County. Hailstones, some the size of tennis balls, hammered southern Wisconsin on Thursday night, denting cars and covering lawns as the storm moved west to east. The largest specimen, with a diameter of

24 National Climactic Data Center. (2003). http://www4.ncdc.noaa.gov/cgi-win/wwcgi.dll?wwevent~storms


4.25 inches, was found in Jefferson County, said Darrin Hansing, a National Weather Service meteorologist. In southwestern Wisconsin, a weather service employee recorded 2.5-inch hail in Dodgeville around 9 p.m., and an Iowa County law enforcement officer saw hailstones 2.75 inches in diameter. In Madison, trained weather service spotters reported 2-inch hail on Fish Hatchery Road and 1.75-inch hail at West Towne Mall about 9:30 p.m. A few minutes later, other spotters reported 3-inch hail in Monona and Cottage Grove. Major damage was done to automobiles in Madison area. Homeowners suffered major damages as roofs and shingles were severely damaged by the hail.

April 18, 2006

Severe storms, with large hail and damaging, straight-line, downburst winds, developed ahead and along a cold front, which plowed east into an unseasonably warm, moist airmass over southern Wisconsin. The hail stones ranged from 3/4 inch to 2 inches in diameter, resulting in several vehicles receiving dents (in Lafayette, Sauk, and Dane County). The damaging winds were mostly in the 60 to 70 mph range resulting in numerous reports of uprooted trees. Dozens of power lines were pulled down as broken tree branches fell on them.


The frequencies of past hail events provide a base line to predict the risk of future occurrences. Hail events are documented multiple times each year, and there are no climactic indications that these occurrences will change in the measurable future. Based on the past history of events, hail has a 100 percent chance of occurrence in a given year, which correlates to a highly likely occurrence rating.

Impact Assessment

While hail is usually a geographically isolated event, it is rarely isolated meteorologically. Hail almost always occurs in conjunction with a severe thunderstorm. Storms capable of producing large hail are also likely to produce lightning, high winds, heavy rain, and possibly tornadoes. Damages associated with these storms result from the combination of all of these factors.

Insurance industry representatives involved in this planning effort indicate that a large hailstorm is one of their greatest concerns in terms of potential losses and insurance payouts. Hailstorms can cause extensive property damage in both urban and rural settings. Most hailstorms produce marble size or smaller hailstones, which can damage crops, but do not typically cause damage to automobiles or buildings. Larger hailstones can destroy crops and can cause extensive damage to buildings, including roofs, windows, and siding. Vehicles and even aircraft can be a total loss. When windows or roofs are damaged due to hail, water damage from often accompanying heavy rain can be significant. A major hailstorm can cause cumulative damages to crops and personal property running into the millions of dollars. Serious injury and loss of human life, however, are rarely associated with hailstorms.


No deaths or injuries have been directly attributed to hail in Dane County. According to the National Weather Service, financial losses due to hail are approximately $7.5 million in property damages since 2002. As a result, the impact assessment of hail is moderate.


In general, all Dane County agricultural crops, buildings, and vehicles are to some degree vulnerable to hail damage. The essential functions of the critical facilities are not likely to be impacted by hail. Nor are any at-risk populations any more vulnerable than the general population. Table 4.22 summarizes the County’s potential exposure to hail damage:

Table 4.22 Property Vulnerable to Hail Damage

Item Number Estimated Value

Crops

Corn for grain or seed (acres) 158,370 Varies

Corn for silage (acres) 25,392 Varies

Wheat (acres) 4,759 Varies

Soybeans (acres) 87,185 Varies

Forage (acres) 78,264 Varies

Vegetables harvested for sale (acres) 2,446 Varies

Residential improvements (parcels) $16,348,209,309

Commercial improvements (parcels) $6,291,971,200

Automobiles 350,000 Varies

The numbers in Table 4.22 represent the total, cumulative value of property and crops that are exposed to the potential for damage or destruction due to hail. Damaging hail does not affect the entire County in one event. Hail is a geographically isolated event that affects only several square miles at any one time. In terms of crop losses, the actual damages that occur will depend on the type of crop and the growth stage of the plants when the hail occurs. In terms of property losses, the actual damages will depend on the housing density and density of automobiles in the impacted area. This is highly variable across the County. A storm with large hail over a crowded shopping mall on a Saturday afternoon will have a significantly different impact than the same storm over a suburban area in the evening when most of the cars are parked in garages. Likewise, a hailstorm in a rural area in the early spring when the plants are just emerging will have much less of an impact than a storm of the same intensity occurring later in the growing season when the plants are more susceptible to damage and when there is no time to replant if the crop is a total loss. These facts lead to a vulnerability assessment of medium.

Potential Future Losses and Development Trends

The potential for future losses due to hail damage is estimated based on an extrapolation of losses from past events. There are limitations to this method:

• Hail damage is not typically a meteorologically isolated occurrence. Damages occur in conjunction with high winds and heavy rain and storm damage estimates are usually


cumulative of all of these effects. The NCDC website provides data on only a handful of events where significant hail damage estimates are isolated from other causes.

• The exposure to damage increases as the population of the County increases. Future damages may increase simply due an increase in the amount of exposed property.

• The damages resulting from a hailstorm depend greatly on where and when the storm hits. The use of average losses from past events does not account very well for these variables.

The NCDC database indicates that since 2003, Dane County has seen more than 37 hailstorms with hail size greater than .75 inches, ten occurrences with hail at least 2 inches in diameter, and six of those events causing over $7.6 million in reported damages. Using statistics and averages, based on the data collected in the NCDC database, an average correlation between hail damage and size can be extrapolated. The damage amount is cumulative, and drawn primarily on inference, as not all events reported a damage estimate. Therefore, this estimate is only a rough prediction of potential damage for any given hail event. In the last twenty years, the average size of hail falling in the County is 1.14 inches and the total reported damages to crops and property is about $8.1 million. Assuming that the damage was evenly distributed over the twenty year span, the average hailstorm is predicted to cause approximately $150,000 worth of damage.


Hail poses risk to the structures and facilities of Dane County, as well as automobiles. Hail’s greatest threat is to agricultural commodities produced in Dane County. As demonstrated in the past history data, the occurrence of hail is common in Dane County. Since hail only affects small portions of the County at any one time, the overall risk for hail is medium.

Table 4.23 Overall Risk for Hail


Geographic Extent Significant 3


Vulnerability Assessment Moderate 2

Impact Magnitude and Severity Medium 2


4.2.7 Landslides, Sinkholes and Erosion

Description

Landslides, sinkholes and erosion are geological phenomena that can pose a hazard to structures and people. Although none of these events are likely to cause a major natural disaster in Dane County, all three present some level of risk to the County’s citizens.

A landslide is a relatively sudden movement of soil and bedrock downhill in response to gravity. The movement of the soil can cause damage to structures by removing the support for the foundation of a building or by falling dirt and debris colliding with or covering a


structure. Landslides can be triggered by heavy rain, bank or bluff erosion, or other natural causes.25

A sinkhole is a depression in the ground caused by an evacuation of support from below the soil. Sinkholes can form naturally in areas with karst geology – areas that have limestone or other bedrock that can be dissolved by water. As the limestone rock under the soil dissolves over time from rainfall or flowing groundwater, a hollow area may form underground, into which surface soil can sink. Sinkholes also can be caused by human activity. Identifying areas with karst conditions is important, and not just for public safety and the protection of structures. Karst features provide direct conduits to groundwater. Areas with karst conditions can be subject to groundwater contaminants from pollutants entering a sinkhole, fissure or other karst features.26

Erosion is the detachment and movement of soils or rock fragments by water, wind, ice or gravity.27 Erosion may contribute to the likelihood and occurrence of landslides, particularly when stream banks or bluffs are eroded. The State Hazard Analysis from 2002 cites several examples where structures that were otherwise considered not vulnerable to landslides and flooding were endangered due to soil and streambank erosion.28 Plans for regulating potential sources of erosion, including stormwater, streambank, farming, and construction sites, appears multiple times in the Dane County Comprehensive Plan (published in October of 2007) and indicates that mitigation efforts for erosion are ongoing.

Geographic Extent

According to the United States Geological Survey (USGS), “Landslides occur in every state and U.S. territory. The Appalachian Mountains, the Rocky Mountains and the Pacific Coastal Ranges and some parts of Alaska and Hawaii have severe landslide problems. Any area composed of very weak or fractured materials resting on a steep slope can and will likely experience landslides.”29

In Wisconsin, landslides generally are not dramatic. However, there have been instances of bluff slumping along the shore of Lake Michigan, rock fall along the bluffs of the Mississippi River and the collapsing of hillsides during heavy rainfall. 30 Figure 4.18 indicates areas of landslide incidence and susceptibility. For Dane County, most of the land demonstrates both a low susceptibility and incidence. The southwest corner of the county demonstrates a moderate susceptibility and low incidence occurring, while a small portion just north of Madison demonstrates a high susceptibility and low incidence of occurrence. Steep slopes are another indicator of potential landslide problem areas, or areas that may have development constraints. Slopes greater than 12 percent are shown in Figure 4.20. The map indicates a concentration of these slopes in the western County.

Some parts of southern and western Wisconsin have experienced sinkholes from abandoned underground mines that have collapsed. 31 Areas with karst potential are indicated Figure

25 Wisconsin Emergency Management “State Hazard Analysis November 2002” p 63. Available online at http://emergencymanagement.wi.gov/docview.asp?docid=116 last accessed February 10, 2009. 26 Ibid., p 64. 27 Dane County Department of Emergency Management, “Dane County Flood Mitigation Plan July 2004” p 107. 28 Wisconsin Emergency Management, “State Hazard Analysis November 2002” p 64. Available online at http://emergencymanagement.wi.gov/docview.asp?docid=116 last accessed March 23, 2009. 29 USGS “Landslides Hazard Program: Landslides 101.” Available online at http://landslides.usgs.gov/learning/ls101.php last accessed February 10, 2009. 30 Wisconsin Emergency Management “State Hazard Analysis 2002” p 63 31 Ibid., p 64.


4.19. The majority of Dane County demonstrates a deeper karst potential, which indicates that the process occurs deeper than five feet below the surface. There are scattered shallow karst potential regions in the southwest corner of the County, consistent with the landslide susceptibility mapping and the presence of the “Driftless Area”. The “Driftless Area” is primarily composed of southwestern Wisconsin, and portions of Minnesota and Illinois, categorized by the lack of glacial drift, or the deposits of debris left behind glaciers. Shallow karst potential indicates the potential for the karst process to occur anywhere between the surface and five feet below the surface.

By contrast, significant portions of Dane County are susceptible to erosion, from a variety of sources. The extent of landslide susceptibility is more than 10 percent but less than 50 percent of the total county area, meriting a significant geographic extent rating. Karst geology is more widespread, covering at least 80 percent of the total county area and is thus rated as geologically extensive. A combined rating is reflected in the overall hazard rating at the end of the chapter.

Figure 4.19 National Landslides Hazard Map


Source: USGS “Landslides Hazard Program: Learning and Education” http://landslides.usgs.gov/learning/nationalmap/. Note: Susceptibility not indicated where same or lower than incidence. Susceptibility to landsliding was defined as the probable degree of response of [the area] rocks and soils to natural or artificial cutting or loading of slopes, or to anomalously high precipitation. High, moderate, and low susceptibility are delimited by the same percentages used in classifying the incidence of landsliding. Some generalization was necessary at this scale, and several small areas of high incidence and susceptibility were slightly exaggerated.

Figure 4.20 Wisconsin’s Shallow Karst Potential (Dolomite Bedrock)

Source: Wisconsin Geological and Natural History Survey, http://www.uwex.edu/wgnhs/karstmap.htm


Figure 4.21 Slopes Steep Slopes - Greater 12%



The Town of Westport submitted the following previous events for landslides and erosion:

During the initial development of the Waunakee Castle Creek neighborhood, there was a large mud slide off the hill which actually damaged some homes under construction along Manchester Crossing and along a drainage system currently in place. During heavy rains, farming practices utilized on a Westport farm located near the intersection of Division and Main resulted in a great deal of sediment flow directly across Division Street and into Six Mile Creek. There was also a great amount of sedimentation moving across Woodland Drive near Mill Road in Westport when the Waunakee Southbridge development was under construction. As of spring 2009 there is still significant water drainage from this area but it is not muddy or silty. During the construction of Bishops Bay on the north shore of Lake Mendota, in Westport, a large quantity of mud washed into the lake because several erosion control measures failed during a heavy rain. There have also been some minor slides into Lake Mendota from properties on the steep portions of the shoreline that were engaging in construction efforts.

Other examples of landslides and sinkholes in the County are not detailed specifically, but are reflected in the numerous erosion controls and ordinances in the County.

There are no documented occurrences of problems associated with sinkholes in Dane County available as of 2008.


There are not enough previous occurrences of landslides, sinkholes, or erosion to calculate a recurrence interval. Based on the absence of documented events, it is assigned a low occurrence rating. It is possible that these events may be occurring more frequently, but having little impact to existing development. Erosion events happen constantly as an ongoing geologic event, but damaging impacts occur less frequently.

Impact Assessments

Direct Impacts

Direct impacts of these hazards impact essential infrastructure and natural resources primarily, with additional, but less severe, impacts on critical facilities and response capabilities. Landslides impact the integrity and navigability of roads, rail lines, and waterways by filling the passages with soil and debris. This impacts the direct usage of the transportation networks and creates secondary impacts on the movement of supplies and goods, including critical supplies such as medications and foodstuffs, between distribution points and commercial centers. Erosion directly impacts the ecology of the County, as discussed in the Comprehensive Plan.

Hydrologic disruption gives rise to physical and ecological impacts as well. Enhanced runoff causes increased erosion from construction sites, downstream areas, and stream banks. The increased volume of water and sediment, combined with the “flashiness” of these peak discharges, result in wider and straighter stream channels. There is substantial loss of both streamside (riparian) habitat through erosion, and in-stream


habitat as the natural streambed of pebbles, rocks and deep pools are covered by a uniform blanket of eroded sand and silt. Loss of tree cover leads to greater water temperature fluctuations, making the water warmer in the summer and colder in the winter.32

Landslides, sinkholes and erosion could impact the ability of response capabilities to navigate between areas. Population, general property, and cultural or historic resources are only impacted directly on a case-by-case basis, where a landslide, sinkhole, or erosion event directly strikes these specific areas. There is no quantifiable way to assess these incident-specific impacts outside of actual occurrences. Examples may include sinkholes damaging structures or croplands, erosion changing previously protected structures into exposed properties for flooding, or landslides damaging physical properties.

Indirect Impacts

The indirect impacts of erosion augment the probability and likelihood of other hazards, including landslides and flooding. The effects on water ecology are also profound, but exceed the scope of this planning process. Chapter 5 of the Comprehensive Plan expands on these details. Landslides may indirectly impact the landscape, which may also have land use or recreational repercussions. Revenue losses are possible due to inaccessibility of affected areas, lost agricultural income due to field degradation, and loss income from natural resources such as parks and waterways due to contamination, damage, or destruction caused by landslides, sinkholes, or erosion.

Magnitude, Severity and Impact Summary

There are not significant reported incidents of landslides or sinkholes in the County, although the karst maps indicate that the potential for these events is present over a large geographic area. The karst maps also indicate that the geography of the County does not lend itself to catastrophic landslides or sinkhole scenarios. The anticipated severity of these events is relatively minor, as no documented injuries, deaths, impacts on essential facilities and services, or significant property damage has been reported.

The significant efforts already in place to mitigate erosion by land use and erosion control ordinances reflect the progress of the County regarding erosion hazards. These measures indicate that erosion posed a very large hazard and/or water quality issue to the County, but is steadily being addressed and mitigated. For now, the overall magnitude, severity and impact rating is minor, both because of the lack of documented events and the large amounts of mitigation efforts already in place. These efforts must be continued, however, for the rating to remain low.


The overall exposure of the County to landslides and sinkholes are difficult to quantify, as the events generally impact specific buildings or aspects of land and the predictability of those is variable. However, some attempt below is made to examine potential vulnerability for planning and mitigation efforts. Erosion potentially affects a greater number of properties and facilities, but it is also a heavily mitigated hazard within the County, as

32 Dane County Comprehensive Plan Vol. II, p 182.


demonstrated by the numerous zoning and erosion control ordinances. Overall, the average vulnerability assessment rating for these hazards is minor.

Population

In general, the population is not overly vulnerable to landslides, sinkholes or erosion except for specific and unpredictable incidents. For example, populations with vehicles are theoretically susceptible to sinkholes in roadways, but there is not a measurable means for examining this vulnerability. Thus the overall vulnerability of population is low.

General Property

General property is only vulnerable to landslides, sinkholes and erosion when it directly strikes the property. The County has several ordinances and controls in place to regulate the development and use of land to prevent most occurrences of erosion. There is not a standard means of examining vulnerability of general property to these hazards without better documentation of previous occurrences or mapping of hazard areas. The continued emphasis on zoning, “smart growth” community plans, and land use ordinances indicate that the County is pre-mitigating the potential for these hazards, rather than reacting to the hazards. The overall vulnerability rating for general property is low.


Dane County had over 43,842 acres developed for transportation usage as of 2000. An additional 6,800 acres were devoted to developed communication, utilities, institutional and governmental uses. Broadly, all of these areas are considered essential infrastructure or critical facilities of some kind. Transportation networks are the most exposed aspect of the County to erosion, landslide and sinkhole incidents because the associated impacts are highest. The loss of transportation networks could potentially cause secondary damage to the overall County’s infrastructure, including revenue, transportation availability, emergency response mechanisms and other essential capabilities by preventing the means of these resources from activating or moving between locations. The vulnerability of the physical buildings and capabilities themselves are more like those outlined in the General Property section of this profile. Again, without more specific past occurrence incidents or hazard mapping, it is difficult to quantify the vulnerability of these facilities. The overall vulnerability rating is considered medium.


Natural resources are perhaps the most exposed element of the County to these hazards. Because landslides, sinkholes and particularly erosion directly impact the geographic makeup of the County, and the associated ecology, these hazards primarily directly impact the natural resources of the County. Historic and Cultural resources experience a vulnerability rating similar to that of General Property, where data and assessments rely more on specific occurrence than a generalization of the event. Overall, because of the potential impacts on natural resources, the vulnerability rating is medium.



There is little data to base a future loss estimate on for these hazards. Generally, the anticipated loss is expected to be limited. This is largely due to the fact that the areas


potentially at risk (southwest Dane County) are also the least developed areas of the County.

Development Trends

Development pressures in Dane County have potential to increase the problems associated with landslides, sinkholes, and erosion, but these impacts can be mitigated by wise land use planning. Construction is consistently cited as a source of erosion, and poorly engineered fill can become landslide hazards. The expansion of the population continues to infringe on natural wetlands and natural landscapes, which increases the potential of erosion and groundwater depletion. As groundwater tables continue to fall, the potential for sinkholes increases. Landslides can often be mitigated by avoiding steep grading in development areas.


As noted in the hazard description, neither landslides, erosion, nor sinkholes are likely to be the cause of a major natural disaster, and thus the overall risk rating is low. However, there is the potential for these hazards that should be considered in land use practices and decisions. This section should be reviewed and updated as more data becomes available. Table 4.24 provides the summary for how all aspects of the hazard profile were evaluated to establish an overall hazard rating.

Table 4.24 Risk Summary for Landslides, Sinkholes, and Erosion


Geographic Extent Significant 3.0

Probability of Future Occurrence Low 1.0

Vulnerability Low 1.0

Impact Magnitude and Severity Minor 1.0

Summary Risk Rating: Low 1.5

4.2.8 Lightning

Description

At any given moment, there are 1,800 thunderstorms in progress somewhere on the earth. This amounts to 16 million storms each year. Lightning detection systems in the United States monitor an average of 25 million strokes of lightning from the cloud to ground every year. . According to the Vaisala Group, an average of nearly 300,000 cloud-to-ground strikes hit Wisconsin each year based on data from 1996 to 2005.

Lightning is caused by the attraction between positive and negative charges in the atmosphere, resulting in the buildup and discharge of electrical energy. This rapid heating and cooling of the air produces the shock wave that results in thunder. During a storm, raindrops can acquire extra electrons, which are negatively charged. These surplus electrons seek out a positive charge from the ground. As they flow from the clouds, they knock other electrons free, creating a conductive path. This path follows a zigzag shape that jumps between randomly distributed clumps of charged particles in the air. When the two charges connect, current surges through that jagged path, creating the lightning bolt. Each spark of


lightning can reach over five miles in length, soar to temperatures of approximately 50,000 degrees Fahrenheit, and contain up to 100 million electrical volts.33

Geographic Extent

Lightning can occur anywhere. All thunderstorms create lightning, and lightning may strike as far as 10 miles away from a thunderstorm.34 The geographic extent of lightning is global, and therefore is usually classified as extensive. The available data regarding lightning events in Dane County further supports this rating, as no region of the county demonstrates an immunity or lower percentage of occurrence than another. However, lightning strikes that cause problems are typically isolated incidents, thus the classification of isolated is assigned.

Figure 4.23 indicates the density of lightning strikes by County in the United States, normalized by population density and implies lightning strike risk level relative to other areas of the country. According to this map, no portion of Wisconsin experiences high flash density. However, relative to the rest of the state of Wisconsin, Dane County falls in the region that experiences the most lightning flash density. This information is further supported in Figure 4.22, which depicts the number of lightning strike events, including associated deaths and injuries, for the entire state of Wisconsin by county. However, Wisconsin lightning data in Figure 4.2.8 (a) is not complete and is based only on newspaper reports. Some lightning incidents are not reported in newspapers. Nonetheless, according to this information, Dane County experiences the second highest number of lightning strikes in the state.


From a national perspective, Wisconsin has a moderate to moderately high risk to lightning-related injury, death and property damage. Wisconsin ranked 28th in the nation for most lightning-related casualties in the period between 1990 and 2003, with 12 reported deaths. Between 1959 and 1994, Wisconsin residents sustained 194 injuries and ranked 16th in the nation for property damage, with more than 500 reports of damage. Actual dollar losses are not specified.35

33 NOAA, “Lightning Safety.” Available online at http://www.lightningsafety.noaa.gov/science.htm, last accessed on February 9, 2009. 34 FEMA, “Thunderstorms and Lightning” Available online at http://www.fema.gov/hazard/thunderstorm/index.shtm, last accessed on February 5, 2009. 35 National Lightning Safety Institute, “Lightning Fatalities, Injuries and Damage Reports in the United States, 1990-2003.” Available online at http://www.lightningsafety.com/nlsi_lls/fatalities_us.html, last accessed February 9, 2009.


Figure 4.22 Lightning Events for Wisconsin (1982-2008)



Figure 4.23 Lightning Flash Density for the United States


Statistics for Dane County are reflected in the risks of the state. Between 1995 and 2008, 40 lightning strikes have occurred in Dane County where damage to person or property has occurred. One death occurred in August 2007 and 10 people have sustained injury over this period. Lighting caused an estimated $1.8 million in property damages between 1995 and 2008. As an example, the NCDC database records a single thunderstorm passing through Dane County on August 2, 2001 that started 5 house fires in 5 different communities.

The NCDC database records severe storms that result in lightning damage. A selection of these events is listed below.

July 6, 2003

Lightning struck a home in Middleton, resulting in a roof/attic fire.

August 22, 2007

A thunder storm lightning strike to a utility pole caused a live wire to fall in a puddle of water at a bus stop as people were getting on a bus in Madison. Three people were killed and a fourth was injured.

August 27, 2007

A man playing golf Monday in Madison died after he was hit by lightning. The golfer sought shelter from the rain under a pine tree but was struck anyway. This was the second deadly incident caused by a lightning strike in Madison in a week.


Lightning events in Dane County show no indication of lessening. Though records on the NCDC database are only available since 1996, severe thunderstorms are documented back into the 1800s. Since all thunderstorms produce lightning of some kind, it is reasonable to assume that lightning strikes have also always occurred in Wisconsin.

Using the formula established in Section 4.2.1 Profile Methodology, the assessment reflects (42 events over [divide by] 12 years) x 100 = 100 percent chance of occurrence and a highly likely future occurrence rating. This occurrence information is drawn from the NCDC database for lightning events in Dane County.

Impact Assessment

Direct Impacts

Lightning follows the shortest, easiest path to earth and often follows several paths simultaneously. Lightning strikes buildings or other objects because the materials in them provide easier paths to the ground than the air. Lightning is more likely to strike on projecting objects such as trees, poles, wires or building steeples than on large, flat surfaces located at the same height or lower. Lone buildings are also primary targets. Lightning can enter a building through a direct strike, by striking a metal object attached to the building, by leaping over to the building after striking a nearby tree, or by following a power line or ungrounded wire fence attached to a building.


Lightning is often perceived as a minor hazard. The effects of lightning, however, can be significant, causing property damage, injury, and death. Damage from lightning occurs in four ways:

• Electrocution, severe electrical shock, and burns of humans and animals • Vaporization of materials in the path of the strike • Fire caused by the high temperatures associated with lightning • Power surges that can damage electrical and electronic equipment

When humans are struck by lightning, the result is deep burns at the point of contact (usually on the head, neck and shoulders.) Approximately 70 percent of lightning survivors experience residual effects such as vision and hearing loss or neuropsychiatric issues. These effects may develop slowly and only become apparent much later.36 Death occurs in 20 percent of lightning strike victims. Nationwide, 85 percent of lightning victims are children and young men ages 10-35 engaged in recreation or work.37

Indirect Impacts

Lightning strikes cause intense but localized damage. In contrast to other hazards, lightning does not cause widespread disruptions with the community. Structural fires, localized damage to buildings, damage to electronics and electrical appliances, and electrical power and communications outages are typical consequences of a lightning strike. Additionally, indirect fatalities may result via electrocution when a person steps from a vehicle into standing water that was previously “charged” by a live power-line that was knocked loose by a lightning strike.

The indirect social and economic impacts of lightning damage are typically associated with the loss of electrical power. Since society relies heavily on electric power, any disruption in the supply, even for a short time period, can have significant consequences. The utilities supplying Dane County have worked closely with emergency response agencies and human services providers to develop plans for responding to planned and unplanned power outages in the County. While Dane County has a generally low vulnerability to wildfires (see Section 4.2.13 Wildfires for more information), they could be an indirect result of a lightning strike.


Based on the above direct and indirect impacts the overall magnitude and severity rating is considered moderate: 5 to 10 percent of property severely damaged, and/or facilities are inoperable or closed for more than a week. 5-10 percent agricultural losses. Fatalities possible but most injuries/illnesses are treatable and do not result in permanent disability. Minor indirect impacts.


Population

While national data shows that lightning causes more injuries and deaths than any other natural hazard except extreme heat, there doesn’t seem to be any trend in the data to

36 FEMA, “Thunderstorms and Lightning” 37 National Lightning Safety Institute, “Lightning Costs and Losses from Attributed Sources”


indicate that one segment of the population is at a disproportionately high risk of being directly affected. Anyone who is outside during a thunderstorm is at risk of being struck by lightning. Aspects of the population who rely on constant, uninterrupted electrical supplies may have a greater, indirect vulnerability to lightning. As a group, the elderly or disabled, especially those with home health care services relying on rely heavily on an uninterrupted source of electricity. Resident populations in nursing homes, Community Based Residential Facilities, or other special needs housing may also be vulnerable if electrical outages are prolonged. If they do not have a back-up power source, rural residents and agricultural operations reliant on electricity for heating, cooling, and water supplies are also especially vulnerable to power outages. These populations are summarized in Chapter 4.3

General Property

According to the event details collected in the NCDC database, the majority of reported damages from lightning are fires to private structures, damage to chimneys or steeples, or small grass fires. Property is more vulnerable to lightning than population because of the exposure ratios. Buildings remain exposed. Mitigation techniques such as choice of building materials or landscaping help reduce the vulnerability of these properties, but there is not data available to segment these properties out of the overall vulnerability assessment.


Some essential infrastructures and facilities can be impacted by lightning. Emergency responders, hospitals, government services, schools, and other important community assets are not more vulnerable to lightning than the general vulnerabilities established for property and population. Some aspects of infrastructure are constructed of materials and/or located in places that increase their vulnerability to lightning. Sometimes, communications and infrastructure are interrupted by lightning strikes. These events raise the vulnerability of the essential functions by delaying response times, hindering interagency communication efforts, or endangering or damaging communication networks.


There are no indications that cultural or historic resources are more vulnerable to lightning than as previously accounted for as general structures. Natural resources may be vulnerable to indirect impacts of lightning, such as wild fires caused by lightning strikes. The presence of large areas of water, or of wide, open spaces in natural habitats may increase the danger of lightning strikes to trees, people, or structures, but these vulnerabilities are not directly related to natural resources. Campgrounds are areas where lightning strikes have more dangerous impacts, so populations utilizing the campgrounds may have a higher vulnerability.



The potential for future losses due to lightning damage is estimated based on an extrapolation of losses from past events. There are limitations to this method:

• The exposure to damage increases as the population of the County increases. Future damages may increase simply due an increase in the amount of exposed property.


• The damages resulting from lightning depend greatly on where and when the storm hits. The use of average losses from past events does not account very well for these variables.

• Indirect impacts are not accounted for. • While the estimation of future losses based on past events is unsophisticated, it still is a

useful method of quantifying the damage potential.

The NCDC database indicates that between 1996 and 2008, Dane County has experienced 40 lightning events where property damage, personal injury or death has occurred. According to the NCDC damages total $1.8 million, injuries total 8, and one direct fatality. Lighting was indirectly responsible for 3 deaths and one injury in 2007. Based on this history and assuming the losses could be proportionately spread over each incident, the estimated average loss per lightning strike event that causes damage is $45,000. Dane County averages 3.2 damaging strikes a year since 1996, which equates to an averaged annualized loss estimate of $145,000. Injuries occur every 1.5 years on average, and deaths every 12 years.

Development Trends

The development of residential areas with parks and open spaces may increase the likelihood of exposed populations occupying those spaces, which in turn raises the vulnerability of the general population. Dane County’s population is growing, which increases the number of people exposed to lightning during a given event. The development of commercial and industrial sectors will minimally impact the vulnerability of the County to lightning. Development plans for more open parks and natural resource protection grounds may increase the potential for exposed populations.


Based on the previous assessments, the overall risk rating for lightning is medium. Table 4.25 provides the summary of all aspects of the hazard profile that were evaluated to establish an overall hazard rating.

Table 4.25 Overall Risk for Lightning


Geographic Extent Isolated 1





4.2.9 Extreme Cold/Wind Chill

Description

Typically, extreme cold temperatures (cold waves) in Wisconsin are accompanied by an active wind that results in an additional wind chill factor. This combination is especially hazardous when temperatures are at least 20 degrees below normal (National Weather Service communication) during the winter season.


Extremely cold temperatures present a variety of problems and impact the population of Dane county both directly and indirectly. Extreme cold is a dangerous situation that can bring on health emergencies in susceptible people, such as those without shelter or who are stranded, or who live in a home that is poorly insulated or without heat. Additionally, extreme cold/wind chill affects agriculture, industry, commerce, and social activities. Extremely cold temperatures may precede, accompany, or follow a winter storm or it may occur during otherwise typical weather conditions.

What constitutes extremely cold temperatures varies across different areas of the United States, based on normal climate temperatures for the time of year. In Wisconsin, cold temperatures are normal during the winter. When temperatures drop at least 20 degrees below normal winter lows, the cold is considered extreme and begins to impact the daily operations of the county. Extreme cold/wind chill impacts inanimate objects, plants, animals and water supplies.

Wind-Chill

The effects of extremely cold temperatures are amplified by strong to high winds that can accompany winter storms. Wind-chill measures how wind and cold feel on exposed skin and is not a direct measurement of temperature. As wind increases, heat is carried away from the body faster, driving down the body temperature, which in turn causes the constriction of blood vessels, and increases the likelihood of severe injury or death to exposed persons. Animals are also affected by wind-chill however cars, buildings, and other objects are not. In 2001, the National Weather Service updated the wind-chill temperature index to take advantages of advances in science and computer modeling technology. Wind-chill effects are shown in Figure 4.24, highlighting the dangers of wind-chill to exposed individuals.

For Southern Wisconsin, including Dane County, the National Weather Service issues Wind Chill Advisories when wind chill values are expected to range from -20 to -34. A Wind Chill Warning is issued when wind chill values are expected to be -35 or lower. For all of Wisconsin, the National Weather Service issues a Wind Chill Advisory when wind chill values are expected to be in the -20F to -34F range (a Cold/Wind Chill documented event in the Storm Data publication), and Wind Chill Warnings for wind chills of -35F or lower (an Extreme Cold/Wind Chill documented event in the Storm Data publication).


Figure 4.24 Wind-Chill Factors


Geographic Extent

Extreme cold/wind chill is generally a regional phenomenon and Dane County is uniformly impacted when it occurs. Therefore, it is considered to have an extensive geographic impact rating. Wind-chill impacts the county with the same variability expected in high-wind disasters. One part of the county may experience significantly colder wind-chill than another, but the movement of the wind also drives the hazard from one location to another. Theoretically, then, the entire county may be impacted by the same hazard at different times. However, because of the variability of wind, the hazard is classified as having a significant geographic impact rating. When the two ratings for the variables within the hazard profile are combined, the overall geographic extent of the hazard is extensive.


The data available on extreme cold/wind chill is limited. A search of data held by the Wisconsin State Climatology Office (SCO) provided observed maximum and minimum temperatures in Madison for every day from January 1, 1971 to December 31, 2008. This data, however, does not indicate wind-chill, nor does it provide any information regarding the impact of severe cold events. The data does provide baseline data for the recurrence interval of such events. Table 4.26 is a summary of the temperature extreme data from the SCO from 1971 through 2008, showing for each month, the number of days with low temperatures less than -10º F.


Table 4.26 Number of Days Below -10º F

Month/Year Number of Days Month/Year Number of Days Month/Year Number of Days

January 1971 10 (3 below –20) January 1979 13

(4 below –20) February 1989 1

February 1971 5 (1 below –20) February 1979 8

(2 below –20) December 1990 2

January 1972 7 (1 below –20) February 1980 1 January 1991 3

February 1972 3 February 1981 1 January 1994 8 (5 below –20)

December 1972 6 January 1982 6 (3 below –20) February 1994 6

(1 below –20)

February 1973 2 February 1982 6 January 1996 2

December 1973 1 February 1983 2 February 1996 6 (4 below –20)

January 1974 2 December 1983 7 (3 below –20) January 1997 2

February 1974 3 January 1984 7 January 1999 3 (1 below –20)

February 1975 1 January 1985 4 (2 below –20) December 2000 4

January 1976 5 February 1985 6 (4 below –20) February 2004 2

February 1976 1 (1 below –20) December 1985 8 February 2005 1

December 1976 6 January 1986 2 (1 below –20) February 2007 1

January 1977 14 (2 below –20) January 1987 1 January 2008 3

February 1977 3 January 1988 10 (1 below –20) February 2008 2

December 1977 1 February 1988 1

January 1978 1 January 1989 10 (1 below –20)

Source: Wisconsin State Climatology Office Website

The National Weather Service and the National Climatic Data Center (NCDC) tracks weather extremes and the related consequences in greater detail. A search of the NCDC website provided the following descriptions of several extreme cold/wind chill and wind-chill events since 1994. These accounts are edited and annotated to reflect only Dane County information.

January 13, 1994

An extended period of extremely cold weather gripped the state. Brisk winds at times combined with record setting sub zero temperatures down to 50 below zero at night to


create wind-chill readings to 80 below zero. During the cold spell numerous schools closed for days at a time, businesses reduced hours, sporting events, winter fest activities, and local government meetings were cancelled. Also many water mains broke and vehicles refused to start. Some people received frostbite and suffered from hypothermia. Heat and power failed in many homes, businesses, and schools. Natural gas and heating oil was consumed at record levels.

December 9, 1995

Bitter-cold arctic air swept into Wisconsin on northwest winds of 20 to 40 mph. Temperatures dropped as much as 15º F in 15 minutes as the strong front moved through. Wind-chill values ranged from -25º F to -50º F. Hypothermia was a secondary cause (indirectly-related) for one death in Dane County. Many schools canceled evening activities, and retailers across the state reported very little shopping activity in spite of the upcoming Holidays. The AAA Club (3,000 calls) and service stations were overwhelmed with requests for assistance with stalled vehicles. There was also a scattering of frozen water pipes that resulted in flooded rooms or basements. At least six frozen water pipe incidents were noted in Dane County.

January 30 – February 4, 1996

After the previous day's ground blizzard, very cold arctic air poured into Southern Wisconsin on northwest winds of 10 to 25 mph. Wind-chills ranged from -35º F to -45º F. Overnight lows across Southern Wisconsin ranged from -5º F to -15º F. Arctic air continued to pour into Southern Wisconsin on northwest winds of 10 to 20 mph overnight. Morning lows dipped to -21º F in Madison. Wind-chills dropped into the -40º F to -60º F range as daytime temperatures never recovered to zero. Service stations were overwhelmed with calls for assistance, and hardware stores reported a booming business due to the demand for space heaters, snow blowers, and other cold-weather gear.

The episode, continued through the first four days of February across south-central and southeast Wisconsin. Ending on the 4th, Madison registered 177 hours below the zero mark. Adding to the misery, wind-chills were in the minus 35º F to minus 60º F range many times during this event. Numerous water main pipes burst, and fiber optic cables froze disrupting telephone service. Schools were closed on the 2nd, and 8,000 homes in Southeast Wisconsin lost electrical service on the 2nd as power companies cut back on output. Service stations and the AAA were overwhelmed with requests for assistance. A new minimum temperature record of -29º F in Madison (now the February record) was set the 3rd.

January 17, 1997

The coldest arctic air of the winter season enveloped southeast and south-central Wisconsin, resulting in many school closings and cancellation of evening activities. Maximum temperatures only reached zero in Madison, roughly 20 degrees below normal. Morning lows ranged from -7º F to -14º F. Coupled with northwest winds of 10 to 20 mph, wind-chills dropped to -30º F to -50º F.

January 5, 1999

The combination of an arctic high pressure ridge, a fresh, deep snow cover, clear skies, and light winds allowed temperatures to plunge to well below zero across south-central and southeast Wisconsin. Observed minimums include Stoughton -23º, and -21º F in Madison.


Thousands of calls to local AAA and car service centers were logged due to stalled vehicles. Maximum temperatures were only around zero.

December 18, 2005

The second cold snap of December 2005 was a contributing or secondary factor (indirect) in the death of a homeless man in Milwaukee. Media news reports indicated that some water pipes (outside faucet) froze on some homes across south-central and southeast Wisconsin. The average temperature across southern Wisconsin for the first 19 days of December 2005 was the coldest since the 1985. Across southern Wisconsin on December 18-19, 2005, maximum air temperatures were only in the teens and lows were around zero to 5 below zero, resulting in daily means around 15 to 17 below normal. In addition, cold temperatures occurred during the period of December 6-8, 2005, when daily means were around 20º F below normal (maximum temperatures in the teens and lows of zero to 10 below zero).

February 3, 2007

The coldest air and lowest wind-chills of the 2006-07 winter season affected south-central and southeast Wisconsin as a massive arctic high pressure pushed southeast through the Western Great Lakes Region over the 4-day period of February 3-6, 2007. Minimum air temperatures tumbled to -5F to -14F on February 3rd with Madison's Truax Field registering -11º F on the 3rd. Daytime maximum air temperatures on the 3rd ranged from 3º F to 10º F. Early morning low temperatures on the 4th ranged from -10º F to -15º F. Afternoon maximum temperatures on the 4th never reached the zero mark, totaling -3º F at Madison. The lowest minimum temperatures of the 4-day period occurred on February 5th. Maximum afternoon temperatures on the 5th ranged from -4º F to 6º F.

On February 3rd and 4th west to northwest winds generally clocked at 15 to 30 mph, which generated wind-chill values of -20º F to -30º F. Lower wind speeds of 5 to 20 mph were noted on February 5th and 6th. In general, the lowest wind-chill values were observed during the early morning hours on February 5th, in the -30º F to -34º F range, corresponding to the lowest air temperatures of the winter season. The cold temperatures resulted in a broken water main and electrical outage in the 100 block of West Main St. near the Madison Capitol Square early Saturday morning, February 3rd. Many public and private schools were closed on Monday and Tuesday, February 5th and 6th. It was the first time in 13 years that the Madison schools closed due to cold temperatures. Additionally, newspaper reports indicated that plumbers answered numerous frozen-pipe calls.

March 27, 2007

On March 27th, a large sink hole developed on State Street in Madison due to a large water main break. This was the 117th water main break in the city of Madison for March, 2007. Usually there is only about 6 to 12 in some of the rougher winter months. Very cold temperatures and little snow cover in the first part of March, 2007, allowed the ground to freeze deeper. Subsequent freeze-thaw periods forced the ground under streets to shift/move, resulting in the numerous water main breaks. Damage was estimated at $300,000.

January 15, 16, 2009

Arctic air blanketed southern Wisconsin and kept temperatures bitterly cold for a 48 hour period. Wind chills reached -35 to -45 F and actual temperatures briefly touched -30 F. All 16 school districts in Dane County cancelled classes, as well as the University of Wisconsin.


Compounding the problem were very slick stretches of road and intersections. Snowfall of almost two inches covered the icy patches making already slippery roads even more dangerous. Road crews worked around the clock to apply sand and salt, but the bitterly cold temperatures rendered the salt virtually useless. Dozens of cars and trucks were involved in slide offs, rollovers, and fender benders on area streets and highways.


Historical data indicates that extreme cold/wind chill is an annual occurrence in Dane County, and there are no climactic indications that the hazard will decrease in the measurable future. Using the formula established in Section 4.2.1 Profile Methodology, the assessment reflects (13 events over [divide by] 9 years) x 100 = 100 percent chance of occurrence and a highly likely occurrence rating.

Impact Assessments

Direct Impacts

Direct impacts are rated based on the actual affect of extreme cold/wind chill on the category being evaluated. The major impact of extreme cold/wind chill is frostbite and hypothermia. Frostbite occurs when the blood flow to the body diminishes enough to prevent adequate heating, and the flesh begins to freeze. It generally begins in the extremities (fingers, toes, tips of ears and nose) and, if untreated, can lead to permanent damage or the loss of limbs. Hypothermia occurs when the body’s core temperature drops below minimum sustainability levels and key organs begin to fail, which can also lead to permanent injury or death. The longer the event lasts, the higher the risk of these vulnerable populations becomes. A study issued in December of 2008 indicates that extreme cold/wind chill is the second-highest cause of death in natural disasters.38 This study is refuted by another article which examines death certificates (noting the medical cause of death) for the same time period. This essay finds that extreme cold/wind chill is the number one cause of death during natural disasters.39 The CDC also recognizes the hazards of extreme cold/wind chill and offers resources targeted at individuals and families to mitigate the effects of extreme cold/wind chill, however, it provides no specific data for analysis.

Indirect Impacts

Indirect impacts examine those costs which are associated with, but not directly caused by, extreme cold/wind chill. For example, the loss of revenue to retail businesses as a result of persons staying indoors during extreme cold/wind chill events. Since very little data is collected on these indirect impacts it is difficult to make a statistical estimation of severity.


The impact magnitude and severity ratings for the population borders between critical and catastrophic based on the average yearly fatalities caused by extreme cold/wind chill. However, while the percent of population affected is not specifically outlined in the

38 Kevin A. Borden and Susan L. Cutter, “Spatial Patterns of Natural Hazards Mortality in the United States” appearing in the International Journal of Health Geographics 7:64 (2008). Available online at http://www.ij-healthgeographics.com/content/7/1/64 last accessed March 4, 2009. 39Indur Golklany, “The Deadliest U.S. Natural Hazard: Extreme Cold.” Available online at http://www.cato-at-liberty.org/2008/12/18/the-deadliest-natural-hazards-for-the-united-states-%e2%80%94-extreme-cold/ last accessed March 4, 2009.


magnitude/severity rating scale, it must be assumed that while the population does experience some fatal or permanent injury events, the majority of the population is not unduly exposed to the hazard. The impact magnitude and severity of the hazard for the majority of the population is moderate. The magnitude and severity of the hazard on property, critical infrastructure and natural, cultural and historic resources is also moderate. Overall a moderate magnitude/severity rating is most appropriate for the extreme cold/wind chill hazards.


Population

While everyone is vulnerable to extreme cold/wind chill events, some populations are more vulnerable than others. Extreme cold/wind chill pose the greatest danger to outdoor laborers, such as highway crews, police and fire personnel, and construction. The elderly, children, people in poor physical health, and the homeless are also vulnerable to exposure. Overall, the population has a medium exposure to severe cold.

General Property

Extreme cold/wind chill presents a minimal risk to the structures of Dane County. Property damage occurs occasionally when water pipes freeze and break. Homes without adequate insulation or heating may put owners at a higher risk for damages or cold-related injury. In cases of periods of prolonged cold, water pipes may freeze and burst in poorly insulated or unheated buildings. Vehicles may not start or stall once started due to the cold temperatures and the risks of carbon monoxide poisoning or structure fires increases as individuals attempt to warm cars in garages and use space heaters. Stalled vehicles, or those that fail to start, may result in minor economic loss if individuals are unable to commute between work, school, and home. Driving conditions may deteriorate if extreme cold/wind chill prolongs icy road conditions, which will impact commutes and emergency response times as well. Landscaping and agricultural products may be damaged or destroyed by unseasonable occurrences of extreme cold/wind chill, causing plants to freeze and die. This may increase the indirect vulnerabilities to severe cold by causing greater economic costs and losses for the year. The overall vulnerability of general property is low.


Like general property, extreme cold/wind chill events have a limited impact on the physical property of essential infrastructures and facilities. Communications lines such as fiber optic cables can freeze. There may be incidents of delayed emergency response due to stalled vehicles, delays in dispatching due to frozen communications lines, or an increased volume in calls. Hospitals may see an increase in cold-related injuries directly or injuries associated as secondary effects of the cold (traffic accidents, broken bones or severe cuts due to slips, etc.) and a prolonged extreme cold/wind chill event may impact hospital personnel capabilities. Personnel working in the cold, such as firefighters, EMTs, police officers and construction workers, have a higher vulnerability due to exposure times, and response capabilities may be hindered. Human services programs that care for at-risk individuals and families may be stressed, but usually can still adequately provide services through the duration of the extreme cold/wind chill event. Unusually high volumes of individuals seeking shelter or food may overwhelm some facilities if the event is prolonged. There may be an increased number of displaced individuals or families due to flooding caused by ruptured pipes, which may strain local aid organizations such as the Red Cross. If the event is extremely extended and impacts multiple other counties and states, which in turn impacts


the availability of mutual assistance, the risk factors may increase. The overall vulnerability of essential infrastructure is medium.


Natural and cultural resources such as campgrounds, lakes, state, county and national parks, and other outdoor venues may suffer vegetative or structural damage from extreme cold/wind chill with the same risks as those outlined in general property. The indirect impacts may increase the vulnerability of these resources to economic loss, as the attendance of outdoor venues in severe cold lessens. Older venues or historical properties suffer the same vulnerabilities associated with private and general properties that are older, with the added vulnerability of damaging historic and often irreplaceable property in the process. The overall vulnerability of these resources is medium.



Property losses due to extreme cold/wind chill are typically minor and isolated. Direct impacts such as water breaks, which may cause water and flooding damage to structures and their contents, are the most likely source of potential property losses. Insurance claims are a potential source of information to verify these numbers, but they were not available for the 2009 update of this plan. There is no reliable data on the county level to quantify the monetary losses associated with critical facilities or infrastructure, but the potential losses to critical facilities is considered minimal.

Potential loss of life and injury due to extreme cold/wind chill is difficult to estimate. Based on statewide severe weather statistics (from Table 4.1), severe cold accounts for 13 percent of all deaths related to severe weather hazards in the state. One method is to examine the number of hospital admissions in a given year for cold-related injury or circumstance, and find the percentage of fatalities from these specific admissions causes. Data from local hospitals was collected on cold-related injuries and deaths in Dane County from 1995-2007. There have been more than 130 admissions of patients as a result of extreme cold/wind chill, with 8 fatalities. These numbers indicate that approximately 6 percent of all cold-related injury admissions to a hospital will result in death. This averages out to roughly 8 extreme cold/wind chill injuries per year, with one death occurring every 1.8 years in this 15 year period. The affected population based on the hospital data was about equal for ages 15 to 24, ages 45 to 54, and ages 75 and above. This belies the assumption that the elderly are more at risk than other population groups. Other than hospitalization records and rough estimates drawn from emergency personnel dispatch records, there are not data sources to further quantify the losses.

Development Trends

New buildings are at a lower risk for indirect damage due to severe cold through utilization of better building materials and insulations. Newer construction may actually decrease the vulnerability of the population it shelters to extreme cold/wind chill, as newer materials and construction techniques may increase the heating effectiveness of residential or commercial facilities. As the population continues to grow and age, the at-risk population will continue to grow as well. There is no current indication that the increasing population will change the overall chance of an exposure-related death in Dane County, however the possibility must be considered. Additional health care facilities or human services locations for at-risk populations will face the same risk levels as existing structures. Public education remains


the primary means of mitigating the risks of extreme cold/wind chill, both to the population and for property protection.


Overall, extreme cold/wind chill presents a high risk for Dane County. The events occur frequently and over significant portions of the county, maximizing the exposed population. While the impacts on structures and the environment are minimal, there are still reports of damage. The ability to quantify these assessments is not currently available, as no accurate financial data for damages incurred exists. Table 4.27 provides the summary of how all aspects of the hazard profile were evaluated to establish an overall hazard rating.

Table 4.27 Overall Risks for Extreme Cold/Wind Chill


Geographic Extent Extensive 4.0

Probability of Future Occurrence Highly Likely 4.0

Vulnerability Assessment Medium 2.0

Impact, Magnitude and Severity Moderate 2.0

Overall Risk Rating High 3.0

4.2.10 Excessive Heat

Description

Excessive heat during the summer season is characterized by a combination of very high temperatures and exceptionally humid conditions. Humid or muggy conditions, which add to the discomfort of high temperature, occur when a dome of high atmospheric pressure settles over the southern part of the country and pulls hot, muggy air north into Wisconsin.

The National Weather Service defines Excessive Heat for southern Wisconsin when these conditions are observed: daytime heat index values of 105 or higher with minimum night heat index values of 75 or higher, for at least a 48-hour period. The National Weather Service issues Excessive Heat Warnings for those conditions. Heat-related deaths may or may not occur during Excessive Heat conditions. The National Weather Service issues Heat Advisories when daytime heat index values are expected to reach 100 to 104. Should 4 consecutive days of heat index values of 100 to 104 be expected, then an Excessive Heat Warning may be issued. History has proven that long durations of heat can adversely affect the general population. A 6 to 7-day heat wave in mid-June, 1995, in which daytime heat index values of 98 to 104 were observed across Wisconsin, there were at least 9 heat-related deaths (National Weather Service).

Heat Index

The National Weather Service uses the “Heat Index” as an estimate of how it really feels when the effect of relative humidity is added to the actual air temperature. The National Weather Service (for the Great Lakes Region, including Dane County) issues Heat Advisories when heat index values are expected to reach 100 to 104 during the daylight hours (for one day or more), or 99 to 99 for four consecutive days. An Excessive Heat Warning is issued when heat index values are expected to reach 105 or higher during the daylight hours and


remain at or higher than 75 at night, for a 48-hour period, or if values of 100 to 104 during the daylight hours are expected for 4 consecutive days. Table 4.26 shows heat index values for a range of temperatures and humidity.

Geographic Extent

Excessive heat is a regional phenomenon often covering large swaths of the United States, and not isolated to counties or states. Figure 4.27 demonstrates the number of heat wave events for the state of Wisconsin from 1982 through 2008, displayed by county. While all counties have documented heat wave events, the number of occurrences increases in the southern and western portions of the state. Heat may be most pronounced in urban areas due to the “urban heat island” effect. Note the high number of heat related deaths in the Milwaukee area. However, the Milwaukee Health Department noted that other social and economic factors were partially the reason for higher number of heat-related fatalities in Milwaukee. The associated geographic extent rating is extensive, with the most pronounced affects in the central, urbanized areas of Dane County in the vicinity of Madison.

Table 4.28 Heat Index Table

Relative Humidity (%)

Temp oF 40 45 50 55 60 65 70 75 80 85 90 95 100

110 136 - - - - - - - - - - - -

108 130 137 - - - - - - - - - - -

106 124 130 137 - - - - -

104 119 124 131 137 - - - -

102 114 119 124 130 137 - - - - - - - -

100 109 114 118 124 129 136 - - - - - - -

98 105 109 113 117 123 128 134 - - - - - -

96 101 104 108 112 116 121 126 132 - - - - -

94 97 100 102 106 110 114 119 124 129 135 - - -

92 94 96 99 101 105 108 112 116 121 126 131 - -

90 91 93 95 97 100 103 106 109 113 117 122 127 132

88 88 89 91 93 95 98 100 103 106 110 113 117 121

86 85 87 88 89 91 93 95 97 100 102 105 108 112

84 83 84 85 86 88 89 90 92 94 96 98 100 103

82 81 82 83 84 84 85 86 88 89 90 91 93 95

80 80 80 81 81 82 82 83 84 84 85 86 86 87

Extreme Danger: Heat Stroke or Sunstroke likely Danger: Sunstroke, muscle cramps, and/or heat exhaustion likely

With Prolonged Exposure and/or Physical Activity:

Extreme Caution: Sunstroke, muscle cramps, and/or heat exhaustion possible Caution: Fatigue possible

Source: National Weather Service Website. http://www.crh.noaa.gov/mkx/summer_page.php



The data available on extreme heat is very limited. A search of data held by the Wisconsin State Climatology Office (SCO) provided observed maximum and minimum temperatures in Madison for every day from January 1, 1971 to December 31, 2008 This data, however, does not indicate heat index, nor does it provide any information regarding the impact of extreme heat events. The data does provide baseline data for the recurrence interval of such events. Table 4.29 summarizes the temperature extreme data from the SCO from 1971 through 2008, showing for each month, the number of days with high temperatures above 95º Fahrenheit. On average, Madison experiences 11 days a year with temperatures above 90º Fahrenheit.


Figure 4.25 Heat Wave Deaths by County for Wisconsin



Figure 4.26 Heat Wave Events by County for Wisconsin



Table 4.29 Heat Incidents for Dane County (1971-2008)

Month/Year Number of Days with high above 95ºF

Month/Year Number of Days with high above 95ºF

July 1971 1 August 1987 1

July 1973 1 June 1988 4 (2 days above 100)

July 1974 4 July 1988 8 (2 days above 100)

June 1976 2 August 1988 7 (2 days above 100)

July 1976 5 June 1994 2

July 1977 6 June 1995 4

Sept 1978 2 July 1995 3 (1 day above 100)

June 1980 1 August 1995 3

July 1980 3 July 1999 1

August 1983 1 July 2001 1

June 1987 1 July 2002 1

July 1987 1 August 2006 1 Source Wisconsin State Climatology Office Website

In more recent years, the National Weather Service and the National Climatic Data Center (NCDC) have been tracking weather extremes and their consequences in greater detail. A search of the NCDC website provided the following descriptions of several excessive heat events, including the most recently documented event in 2006:

June, July 1995

Dane County experienced two periods of prolonged heat in the summer of 1995. From June 17-27, high temperatures were consistently into the 90ºs F with heat index values ranging from 88º F to 104º F. During this period, statewide, 9 people died as a direct result of the heat. The second heat wave, July 12-15, resulted in the greatest number of weather related deaths in Wisconsin history. During this heat wave, 141 people died directly or indirectly from the heat, but no deaths were reported in Dane County. High temperatures were well into the 100ºs, with heat index values of 120º to 130º F.

July 1999

A heat wave over the last two weeks of July, peaking on July 28-31, 1999 pushed local utility companies to the limit. There were no outages in the Dane County area, but there were records set for peak electrical demand. During these four days, high humidity and high temperatures well into the 90ºs produced heat index values to over 110º F. Statewide, the heat was directly responsible for killing 8 people and indirectly responsible for another 6. Dane County had 1 heat-related death.

July 2001

Southern Wisconsin was affected by a heat wave at the end of July 2001. Afternoon heat index values on the 31st reach 110º F for several hours and stayed in the 85º F to 100º F


range through the evening hours. Local utilities again reported new daily record peak demands for electricity. Statewide 15 died because of heat.

October 2003

A 6-month old female died in the city of Middleton. Heat was listed as a contributing cause, thus this death is indirectly related to excessive heat. Maximum temperatures in the Middleton area on October 7th and 8th were around 79º F, about 15 degrees above normal.

July and August 2006

A period of very hot and humid weather began on the evening of July 30th and continued into August 2nd. Overnight temperatures only fell to 70 to 75 on the 30th, and soared into the 95 to 100 degree range during the afternoon of July 31st. With dew points in the low to mid-70s, heat index values only dropped to about 75 overnight on July 30th, and peaked in the 105 to 110 degree range across south-central and southeast Wisconsin during the afternoon of July 31st. An estimated 40 people in Milwaukee County were hospitalized due to heat-related symptoms. Ultimately, this stretch of "heat advisory" conditions resulted in two directly-related heat deaths in Milwaukee County where the urban heat-island effect is enhanced. Air temperatures only fell into the mid 70s across south-central Wisconsin and lower 80s in the Milwaukee Metro area during the early-morning of August 1st. Afternoon air temperatures soared into the 95 to 100 degree range. With dew points in the low to mid-70s, heat index values only dropped into the lower 80s during the morning of the 1st, and peaked in the 105 to 110 degree range across south-central and southeast Wisconsin during the afternoon of August 1st. The oppressive conditions continued during the overnight hours of August 1st with low temperatures around 80 degrees before a cold front swept through during the afternoon, ending the heat wave. On August 2nd, a 67-year-old male died due to high temperatures in his West Allis (Milwaukee Co) residence. Likewise on August 2nd, a 41-year-old male died in his residence due to elevated levels of heat.


Excessive heat events occur about once every other year in Dane County. Though Dane County does not have the highest incidence of heat wave periods, it is located in southern Wisconsin, which is the most area most severely impacted by heat wave events. According to the National Weather Service data shown in Figure 4.26 Dane County has experienced 13 heat wave events in the 27 years between 1982 and 2008. It is extremely likely that heat waves will continue in the future. Using the formula established in Section 4.2.1 Profile Methodology, the assessment reflects (13 events over [divide by] 27 years) x 100 = 48 percent chance of occurrence any given year, or happens on average every 2 years. This equates to a likely occurrence rating.

Impact Assessment

Direct Impacts

The most significant direct impacts of excessive heat are to human health. Some medical conditions, for example, are considered direct impacts of excessive heat. These include dehydration and heat stroke. Adverse health outcomes associated with extreme temperatures include heatstroke, heat exhaustion, dehydration, heat syncope, and heat cramps. Heatstroke is the most serious of these conditions and is characterized by rapid progression of lethargy, confusion, and unconsciousness. It is often fatal despite medical care directed at lowering body temperature. Heat exhaustion is a milder syndrome that


occurs following sustained exposure to hot temperatures and results from dehydration and electrolyte imbalance; manifestations include dizziness, weakness, or fatigue, and treatment is supportive. Heat syncope and heat cramps usually are related to physical exertion during hot weather.

Property impacts from excessive heat are generally minimal.

Indirect Impacts

Indirect impacts examine those costs which are associated with, but not directly caused by, excessive heat. The most common indirect impact of excessive heat is the loss of electricity caused by the overly-high demand for power. This indirect impact from excessive heat increases population vulnerability, as refuge from the excessive heat becomes compromised, and increases the economic impacts associated with power outages. Since very little data is collected on these indirect impacts it is difficult to make a statistical estimation of severity.


Figure 4.25 indicates that Dane County has one documented death caused by excessive heat since 1982. Specific injury reports are unavailable, but hospital records from 1996-2008 indicate that over 200 patients were treated for heat-related injury and illness. According to the National Weather Service, heat waves have been responsible for more deaths in Wisconsin than all other natural disasters combined. For the period 1982 – 2008, at least 116 people have died in Wisconsin where heat was the direct or primary cause. For the same period of time, at least 95 people in Wisconsin have died when heat was an indirect or secondary cause.

Property damage is equally difficult to quantify, as excessive heat does not directly impact property. Based on the known extent of property damage and injury/fatality ratings, the magnitude/severity rating for excessive heat is low.


Population

Everyone is vulnerable to excessive heat conditions, although some populations are more vulnerable than others. Excessive heat poses the greatest danger to outdoor laborers, such as highway crews and fire crews. The elderly, children, and people in poor physical health are also vulnerable to exposure to extreme temperatures, as are the homeless. Mortality among elderly persons, persons with chronic conditions (including obesity), patients taking medications that predispose them to heatstroke (e.g., neuroleptics or anticholinergics), and persons confined to bed or who otherwise are unable to care for themselves are at greatest risk. Low-income individuals and families are also at greater risk of heat exposure than the general population.

According to FEMA, People living in urban areas may be at greater risk from the effects of a prolonged heat wave than people living in rural regions. Asphalt and concrete retain heat longer and gradually release heat at night, which produces significantly higher nighttime temperatures in urban areas known as the urban heat island effect.

Available hospital records from 1996-2008 indicate that no resident of Dane County has died directly from heat exposure. However, there have been over 308 visits by patients


during this time for various reasons, heat stroke being the most common. Some of the patients were repeat visitors. This equates to about 50 people a year. As a percentage of the total population, the population with the greatest risk for heat-related health effects is over age 65. In addition, Figure 4.25 indicates that since 1982 there has been one reported death directly associated with excessive heat in Dane County.

There are also segments of the population that are vulnerable to the potential indirect impacts of prolonged excessive heat, particularly the loss of electrical power. As a group, the elderly or disabled, especially those with home health care services relying on rely heavily on an uninterrupted source of electricity. Resident populations in nursing homes, Community Based Residential Facilities, or other special needs housing may also be vulnerable if electrical outages are prolonged. If they do not have a back-up power source, rural residents and agricultural operations reliant on electricity for heating, cooling, and water supplies are also especially vulnerable to power outages. Overall, the population has a medium exposure to excessive heat events.

General Property

Generally, property is not considered particularly vulnerable to excessive heat. Energy-inefficient buildings may be warmer, resulting in a higher exposure of the population, and personal landscaping and property may suffer from the effects of heat in a manner similar to drought. Cars may overheat, stranding motorists or damaging the vehicle itself and resulting in higher property damage costs. The overall vulnerability of general property is low.


Heat extremes present minimal direct risk to structures and critical facilities of Dane County. Critical facilities may be vulnerable to the indirect impact of prolonged excessive heat, i.e., electrical power outages, which may impact response capabilities or care capabilities for hospitals and clinics. Hospitals and clinics may see a surge in patients during the heat event as the exposed population suffers from the effects of the heat, but it is not anticipated that these increases will overwhelm the capacities of hospitals and clinics in Dane.

The primary stresses to essential infrastructure are on the electrical distribution system as demand increases to run air conditioning. Peak demand exceeding the local utility’s capacity for supply can lead to blackout or brownout conditions. This has not occurred in Dane County however, utilities were very closely monitoring the situation during the heat waves of 1999 and 2001. The utilities supplying Dane County have worked closely with emergency response agencies and human services providers to develop plans for responding to planned and unplanned power outages in the County. The Dane County Electrical Power Disruption Plan was developed to address this issue. The overall exposure of essential infrastructure is medium.


Natural resources may suffer from prolonged exposures to excessive heat, such as the drying of grasses and trees, evaporation from water sources, and an increased likelihood of wildfires. Historic resources likely experience the same vulnerabilities addressed in General Property. Cultural resources themselves are likely minimally impacted by the excessive heat; however the people using those resources may experience a higher vulnerability due to exposure. Playgrounds, for example, may be too hot for safe utilization by children.


Community centers and other resources providing free or low-cost air conditioning may see a drastic increase in attendance, which may stress capacity or use. All of these vulnerabilities are considered minimal. The overall exposure of these resources to excessive heat is medium.



As can be seen from the past history data, excessive heat events are a near annual occurrence in Dane County. The costs and losses from past extreme heat events, however, are not systematically collected and compiled. There is no available data on which to base a projection of the future loss potential, which was recognized in the previous planning process. No new data collection exists to estimate financial damages due to heat. One death was reported in the last 27 years, or a 3.7 percent chance of a single death due to excessive heat in a given year. This is not anticipated to change despite population growth.

Development Trends

Development itself is not vulnerable to excessive heat. Newer construction may actually decrease the vulnerability of the population it shelters to excessive heat, as newer materials and construction techniques may increase the cooling effectiveness of residential or commercial facilities. Population data indicates that the overall population of Dane is expected to continue increasing.


As with severe cold, the most vulnerable aspect of Dane County to excessive heat is the population. Property may experience slight damage as vehicles overheat; contents of garages are damaged due to heat exposure, or natural landscaping experiences impacts similar to drought. Excessive heat increases the risk of wildfire, impacting natural resources. Essential infrastructure is generally not impacted by excessive heat, though clinics may see an increased demand for services as the population is exposed to the heat. Due to the population exposure, and potential fatal impacts, the overall risk rating for excessive heat is medium. The ability to quantify these assessments is not currently available, as no accurate financial data for damages incurred exists. Table 4.30 provides the methodology for how all aspects of the hazard profile were evaluated to establish an overall hazard rating.

Table 4.30 Overall Risk for Excessive heat





Impact, Magnitude and Severity Low 1



4.2.11 Severe Winter Storm

Description

Winter storms occur when below freezing air on the ground and in clouds combine with moisture. Moisture is needed to form clouds and cause precipitation. A storm front lifts the moist air to form the clouds. Storms that affect Wisconsin develop over southeast Colorado, northwest Canada, and over the southern plains. These storms move toward the Midwest and use both the southward plunge of cold air from Canada and the northward flow of moisture from the Gulf of Mexico to produce heavy snow over the region. Alberta Clippers, which develop in the lee of the Canadian Rockies and move southeast toward Wisconsin, not only produce accumulating snow, but can also bring strong winds and extremely cold air to the state.

Winter storms are defined here by the following events: heavy intense snow showers accompanied by winds less than 35 mph that result in snow accumulations of 6 inches or more within 12 hours or less, freezing rain (which occurs when rain falls onto and freezes on cold surfaces) that results in ice accumulations of 1/4 inch or more within 12 hours or less, and blizzards which consist of sustained or frequent gusts of 35 mph or more accompanied by snow and/or blowing snow that reduces visibilities to 1/4 mile or less for 3 hours or more.

Geographic Extent

Winter weather is a regional event that occurs across the entire county or sometimes the entire state. Snowfall can occur anytime between October and May. More substantial winter storms occur during the winter months, most frequently between December and February. January has the most documented occurrences of severe winter weather. Between 1980 and 2008, 87 winter storms passed through Dane County and 90 percent of those storms are considered heavy snow events. Ice storms are second most common, followed by blizzards. January is the snowiest month averaging 12.9 inches with a record snowfall of 31.8 inches. December is the second snowiest month averaging 12.6 inches of snow with a monthly record of 40.4 inches. The winter of 2007-2008 was one of the most severe on record, with over 100 inches of snowfall recorded in Dane County. Severe winter weather has an extensive geographic rating.


The history of past winter storm events was gathered from NCDC data, newspaper reports and other data sources as cited. Winter storms have caused problems for Dane County residents for as long as the area has been settled. Every winter provides some challenges to the population. Some of the most recent outstanding events are listed below.

March 1976

During March 4-11, a storm of freezing rain, snow, ice and wind combined into a severe ice storm that made its way across the southern portion of the state causing $50.4 million in damages statewide, at the time the most expensive natural disaster in Wisconsin history. This estimate is considered to be conservative. Unable to milk or water the cows, farming communities sustained the greatest losses. Farmers lost $17.3 million. Government damages were approximated at $8.4 million, private homes and businesses $11 million to, and utilities $13.7 million.


Of the 22 counties affected from the Mississippi River to Lake Michigan, Dane County was among the hardest hit. Approximately 10,000 residents lost electrical power, some for as long as 11 days. The City of Madison suffered a temporary water shortage as most of the City’s water pumping stations went without power. Without heat, light, or water, many people stayed in emergency sleeping quarters prepared by the Red Cross.

Dane County damages for public, farm, and private/non-farm losses, in 1976 dollars, totaled $1.9 million, $1.8 million, and $1.0 million respectively. Total damages were estimated to be $4.78 million, excluding electric utility losses, which were $1.2 million for Madison Gas and Electric, and an undisclosed amount for Wisconsin Power and Light.

March 8, 1998

Near blizzard conditions brought parts of south-central and southeast Wisconsin to a standstill. The combination of heavy, wet snow, and northeast winds gusting to 40 to 50 mph, reduced visibilities occasionally to below 1/4 mile and created drifts of 8 to 15 feet in areas west and southwest of Madison. Based on newspaper accounts, there were approximately 800 motor vehicle accidents, dozens of toppled power lines, many school closings, and many road closures. Interstate 90/94 and State Highway 51 north of Madison were closed at the height of the storm. In addition, many airline flights and other commercial activities were postponed or cancelled.

December 2000

December 2000 was one of the 10 coldest Decembers on record for most of the state. In addition to the low temperatures, record or near record snow depths of 15-34” occurred in much of southern Wisconsin during December. As a result of record snowfalls, thirteen counties received a Presidential Emergency Declaration and were eligible to receive federal funds for extraordinary expenses associated with clearing roads and emergency response efforts. The counties declared in the snow emergency were Columbia, Dane, Door, Green, Kenosha, Kewaunee, Manitowoc, Milwaukee, Racine, Rock, Sheboygan, Walworth and Waukesha Counties. Local governments in Dane County received a total of $586,000 in federal disaster assistance.

January 30, 2008

A powerful winter storm raked south-central and southeast Wisconsin during the afternoon hours of January 29th into the pre-dawn hours of January 30th. The precipitation started off as rain and thunderstorms then changed to sleet and freezing rain which then changed to snow and blowing snow with plunging temperatures. Peak sustained northwest winds were on the order of 22 to 28 knots (25 to 32 mph) with peak gusts of 34 to 43 knots (39 to 49 mph). Visibilities were occasionally reduced to 1/4 to 1/2 mile in open areas. Dozens of vehicle accidents and slide-offs were noted by the media due to very slippery roads. Afternoon temperatures in the mid 30s to lower 40s quickly dropped through the 20s into the teens and then into the single digits by the evening hours and eventually down to the -4F to -11F by the pre-dawn hours of the 30th. Although new snow amounts were only 1 to 3 inches, County Emergency Management staff noted that this event was perceived as a winter storm due to the combination of thunderstorms, freezing rain, sleet, snow, blowing snow, strong winds, poor visibilities, and fast-falling temperatures. Synoptically, a strong low pressure moved northeast through Minnesota while a strong cold front swept southeast through Wisconsin. Another low pressure developed along the cold front while it was over northern Illinois, which led to a tightening pressure gradient and stronger winds over southern Wisconsin.


February 5-7, 200840

A severe winter storm spanning several days caused a traffic jam and accident involving over 1,000 cars and trucks on the northbound/westbound lanes of I-39/90. Though no injuries or deaths were reported, the damage was considerable. The Governor called a State of Emergency on the interstate and requested assistance from State Troopers from Madison and other jurisdictions within Dane county, and as far out as Wausau, Tomah, and Waukesha, Wisconsin Department of Natural Resources game wardens with snowmobiles, and wreckers were called from all over to try to get cars off the road. A number of graders from highway department were required to clear the roads. 68 soldiers from the National Guard were also called in to assist. Water and food were provided to some victims by troopers and game wardens on snowmobiles. 17 miles of I-39/90 were closed for two days. 78 schools and districts were closed or opened late.


Severe winter storms have been documented since settlement in the region began. Severe incidents are documented more than once yearly, with extraordinarily severe events falling approximately every other year. Using the formula established in Section 4.2.1 Profile Methodology, the assessment reflects (58 events over [divide by] 15 years) x 100 = 100 percent chance of occurrence, which corresponds to a highly likely occurrence rating.

Impact Assessment

The occurrence of major snowstorms, ice storms, and blizzards can have a considerable impact on communities, utilities and transportation systems. Ice storms often produce extensive damage over large regions. The impacts of an ice storm are amplified when frigid temperatures follow the storm. Snow and ice accumulates on roads, highways, railroads, and airport runways and halts transportation efforts. Ice can cause telephone and power lines and tree branches to break and fall, which may damage property, cause injury, and create hazardous conditions. Power outages may last for days, and in some cases, it may be weeks before power is restored to more remote rural areas. As people have become increasingly dependent on electricity for heating and cooking, the possibility of experiencing a loss of electricity for an extended period has become more critical. While some of the direct impacts of ice or heavy snowstorms are easily identified, these can produce a wide range of indirect impacts. Many of these are summarized below.

Direct Impacts

Ice or heavy accumulations of snow, particularly with blowing and drifting, temporarily impact the roadway system. Roads can become impassable with heavy icing or as snow accumulates faster than it can be cleared. Snow and ice resulting in icy road conditions lead to major traffic accidents and numerous minor accidents. Similarly, if roads and streets are icy or snow covered, it is also difficult for emergency service personnel to travel and may pose a secondary threat to life safety if police, fire, and EMS crews cannot respond to calls. Ice or heavy accumulations of snow also require vast amounts of overtime for County and local highway and streets departments to remove snow and melt ice. Additionally, a hypothermia situation may arise due to prolonged exposure to the cold when a person attempts to walk during the height of a major winter storm.

40 Dane County Local Hazard Mitigation Plan Data Collection Guide, 2009.


Heavy accumulations of snow on rooftops can cause roofs to collapse, resulting in possible injury or death to those inside the building as well as damaging the contents of the building. Ice storms or high winds in winter storms can cause extensive loss of overhead utility lines due to buildup either on the lines or on adjacent trees that either collapse due to the weight or blow down onto the utility lines. Services such as telephone, electricity, and cable TV are frequently affected by winter storms.

Indirect Impacts

The indirect impacts are what separate an ordinary winter snowstorm, even a heavy snow, from a disaster. Heavy accumulations of snow or ice can bring down trees, utility lines, and communications towers. This can disrupt communications and electrical power for days while utility companies repair the damage. Loss of power, in conjunction with impassible roads can isolate people in rural areas and essentially shut down urban areas, effectively paralyzing the entire region.

Also, many of the deaths that occur are indirectly related to the storm itself. Many of these results are from traffic accidents or heart attacks while shoveling snow. The indirect impacts of severe winter storms ripple past the actual hazard event. Economic costs incurred by loss of business as a result of the storm, property damages, overtime costs, loss of income due to closed business, and missed school days all have long-reaching effects. Increased amounts of snow may increase the risk of flooding in the summer.

Other examples of indirect impacts include:

• Agricultural losses. Livestock, particularly dairy cattle can be highly vulnerable to the impacts of an ice storm, especially if freezing conditions exist for a long time and are accompanied by an extensive power outage. Daily operations are dependent on electricity for milking and watering the animals. Loss of revenue or even disease and death of the animals can result.

• Home Health Care Services. Recipients of home health care services, particularly in rural areas face disruption of services in the aftermath of an ice or heavy snowstorm. Providers may have difficulty in reaching patients due to debris or downed power lines blocking roadways. Electrically powered life support equipment will fail to operate in a power outage. This can have dire consequences to the patient if the outage is prolonged.

• Communications. Telecommunications can be disrupted due to a variety of factors. Most telephone and cellular carriers have emergency back-up power supplies for primary equipment. In many cases, the back-up power supply is designed to provide power for 48-hours or less. In the prolonged power outages possible with a major ice storm, this equipment will fail when the fuel for the generator runs out or the back-up batteries become discharged. Overhead telephone lines are also susceptible to the same problems as overhead electrical lines. The consequences of communications failure can be far reaching. Coordination of the public safety response to the event relies heavily on the ability to communicate. The response is invariably hampered when these systems fail.

• Public water supply and wastewater treatment. Water supply pumps and wastewater lift stations are vulnerable to prolonged loss of power. Many of these have back-up power supply for short-term power outages. An ice storm, however, has the potential to cause power outages that may last for days.

• Severely damaged trees. Ice or exceedingly heavy snow can cause substantial damage to trees in urban and rural areas. Damaged or fallen trees in urban areas block roads and sidewalks and can take down power lines. Downed or fallen trees in rural


areas can lead to fire hazards in subsequent years as dead trees add to the fuel load. In either case, removal of downed trees and branches can be a significant problem and cost.

• Residential impacts. Loss of power for residential use can lead to a loss of household heating, freezing and bursting water pipes leading to loss of fresh water supply and flooded basements, sewage back-up, and the loss of the ability to cook food.

• Provisions. As is common in many disasters, supplies of flashlights, batteries, shovels, bottled water, fuel, and food supplies may be short in areas immediately affected by the storm. This creates a particular stress on low-income individuals and families that are not able to stock-up on these supplies, and may cause a panic on certain supplies as stock levels drop.

• Economic loss. Dane County residents rely heavily on roadways and automobiles to commute to and from work. When employees cannot get to their jobs, commerce can be affected, especially if the situation lasts for days. In addition, all of the primary and indirect impacts of a major snow or ice storm can have cascading economic consequences.


There are no documented fatalities directly caused by severe winter weather in Dane County, but traffic records (discussed in greater detail in the vulnerability assessment) indicate that winter conditions caused approximately 1,723 accidents in Dane County in 2007, with approximately 10 resulting in at least one fatality. Four winter storm events merited Presidential Disaster declarations for the state in 1976, 1978, 2001 and most recently in 2008. These factors and the extensive indirect impacts of winter storms all combine for a magnitude/severity rating of critical.


Population

While virtually all aspects of the population are vulnerable to severe winter weather, there are segments of the population that are more vulnerable to the potential indirect impacts of a severe winter storm than others, particularly the loss of electrical power. As a group, the elderly or disabled, especially those with home health care services that rely heavily on an uninterrupted source of electricity. Resident populations in nursing homes, Community Based Residential Facilities, or other special needs housing may also be vulnerable if electrical outages are prolonged. If they do not have a back-up power source, rural residents and agricultural operations reliant on electricity for heating and water supplies are also especially vulnerable to power outages.

Severe winter weather also increases the vulnerability of the commuting population. Traffic accidents occurring in winter conditions (snow, blowing snow/sand/dirt, and sleet/hail) accounted for 13,518 accidents in Wisconsin in 2007. 41 of these resulted in at least one fatality, for a rate of 0.3 percent. Icy and snowy roads accounted for 20,756 accidents in the State, 63 of which were fatal at a rate of 0.3 percent. These accidents, combined, accounted for over 21,000 accidents, or 16.8 percent of all accidents in the state. Dane County experienced 10,255 total accidents in 2007, so assuming the corresponding percentage; winter storms caused 1,723 accidents in Dane County in 2007, with


approximately 10 of these accidents resulting in a fatal accident.41 While there is no way to quantify which of these accidents occur during severe winter storms versus regular winter storms, the numbers indicate that winter driving conditions raise the vulnerability of the commuting population. Overall, the population vulnerability to severe winter storms is medium.

General Property

Property vulnerabilities to severe weather include damage caused by high winds, ice, or snow pack and subsequently melting snow. Vehicles may be damaged by the same factors, or temporarily un-useable due to the driving conditions created by severe winter weather. Contents of homes, storage units, warehouses and storefronts may be damaged if the structures are compromised or fail due to the weather, or during potential flooding caused by melting snow. Very wet snow packs down densely and is very heavy. This may create strains on structures, causing partial or entire collapses of walls, roofs, or windows. This is impacted both by architecture and construction material, and should be assessed on a building-by-building basis. These records are probably tracked via insurance or other private vendors. The overall vulnerability rating of general property is considered medium.


The physical structures which comprise essential infrastructure are as vulnerable as those outlined in the General Property subsection of this profile. Severe winter weather may also disrupt the availability of services from essential infrastructure, including utility delivery (gas, electric and water), telephone service, emergency response personnel capabilities, road plowing, and childcare availability. Severe winter storms may even halt the operation of the county for periods of time, making the vulnerability of the entire County even higher.

As mentioned previously, ice or heavy accumulations of snow, particularly with blowing and drifting, can temporarily impact the roadway system. These accumulations also require vast amounts of overtime for County and local highway and streets departments to remove snow and melt ice. Ice storms or high winds in winter storms can cause extensive loss of overhead utility lines due to buildup either on the lines or on adjacent trees that either collapse due to the weight or blow down onto the utility lines. Services such as telephone, electricity, and cable TV are frequently affected by winter storms. The overall vulnerability of essential infrastructure is medium.


Natural resources may be damaged by the severe winter weather, including broken trees and death of unsheltered wildlife. Unseasonable storms may damage or kill plant and wildlife, which may impact natural food chains until the next growing season. Historical areas may be more vulnerable to severe winter storms due to construction and age of structures. Cultural resources generally experience the same vulnerabilities outlined in General Property, in addition to lost revenue impacts due to transportation impacts. The overall vulnerability of these resources is medium.

41 Wisconsin Department of Transportation “2007 Wisconsin Traffic Crash Facts: Section 2, Crashes.” Available online at http://www.dot.wisconsin.gov/safety/motorist/crashfacts/index.htm last accessed March 3, 2009.




The potential for future damages is estimated by assuming similar impacts as those caused by the 1976 ice storm. Public, farm, and private/non-farm losses were $5.8 million, $5.5 million, and $3.3 million respectively. Total damages are estimated to be $14.5 million, excluding electric utility losses, which were $3.6 million for Madison Gas and Electric, and an undisclosed amount for Wisconsin Power and Light (now Alliant Energy). Snow removal costs were approximately $3.6 million. Overall, this totals to $135.95 million in 2008 dollars.

Like fog, winter storms are dangerous hazards on Dane County roadways. Between 1998 and 2002, 604 people were injured and 9 were killed when snow was present on the road and precipitating. That averages to 151 injuries and about 2 deaths per year.

Development Trends

As the County continues to develop, a greater number of structures, roadways, and population are exposed to severe winter storms. More roads will increase the need for snowplows and other means of keeping travel ways clear. Denser populations increase the number of expected injuries and deaths attributed to severe winter storms, but do not reflect an overall increase in the mortality of the disaster itself. Structures built to modern building codes may decrease the amount of general property damage due to heavy snowfalls. Because of growth the current capabilities of emergency response personnel can be taxed or overwhelmed during an event, which compromises the quality of provided services during said events. Potential for future damages could to increase for utilities. Agricultural losses may decrease as the number of cattle and dairies decreases in the County. Injuries to vulnerable populations may increase as those populations increase.


Overall, severe winter storms present a high risk for Dane County. The events occur frequently and over significant portions of the county, maximizing the potential to impact exposed population and structures, and have far reaching indirect impacts. Reports of damage to property and the impacts on essential infrastructure are high. Table 4.31 provides the methodology for how all aspects of the hazard profile were evaluated to establish an overall hazard rating.

Table 4.31 Overall Risk for Severe Winter Storm





Impact Magnitude and Severity Critical 3



4.2.12 Tornado

Description

A tornado is a violently rotating column of air (vortex), extending from the base of a convective cloud (usually cumulonimbus) to the ground. There may or may not be a visible condensation funnel (what most people refer to as the funnel cloud) associated with the tornado. Therefore, a tornado may be nearly invisible since one can not see vortex of rotating air. Literally, in order for a vortex to be classified as a tornado, it must be in contact with the ground and the cloud base.42

Tornadoes usually form under certain types of atmospheric conditions. They are more likely to occur in regions where there are strong contrasts in temperature and humidity across short distances. Nationally, these conditions are most common in the central plains of North America, east of the Rocky Mountains and west of the Appalachian Mountains. They occur mostly during the spring and summer, starting earlier in the south and later in the north. According to A Tornado Climatology of Wisconsin, the typical day with tornadoes usually begins with warm and humid conditions with a few fair-weather cumulus clouds developing vertically over time in the unstable air. Later the first sign of an approaching thunderstorm is observed—a high thin layer of ice clouds called cirrus blowing off the tops of the thunderstorm to the west.43

Rotation in a thunderstorm begins when air entering the storm near the surface is blowing from different direction than air higher in the atmosphere. The rotation usually starts as a roll or horizontal rotation of the air in the lower 10,000 feet of the atmosphere. The warm updraft feeding the storm develops further, lifting one end of the rolling air and transforms the rotating mass into a vertical position. Most tornadoes rotate counterclockwise (cyclonically) in North America. Tornadoes may last for anywhere from a few minutes to up to an hour. The width of a tornado may range from a few yards to over a mile; the path of a tornado may range from a few hundred yards to hundreds of miles.44

Through observational studies, T. Theodore Fujita created the Fujita Scale (commonly known as the “F Scale”) in 1971 to classify tornadoes based on damage caused by the tornado in correlation to wind speed. However, over the years this scale has revealed several weaknesses and in 1992, Fujita published his memoirs called Mystery of Severe Storms which included an updated scale. This updated scale maintained the original classification of tornado wind speeds with damage assessments based on the type of structure. These improvements were incorporated by a committee convened by Texas Tech University (TTU) Wind Science and Engineering (WISE) Research Center to design the Enhanced Fujita Scale, commonly known as the EF Scale. One of the most important factors of the EF Scale is that it includes previous F Scale ratings to create consistency between the initial tornado databases, which stretch back into the 1950s, and the more contemporary measurement systems. This new system still uses wind estimates (not measurements) based on damage to assign scale ratings. It uses three-second gusts estimated at the point of damage based on a judgment of 8 levels of damage to one of 28 indicators (building types and materials). The estimates also vary with height and exposure. A table depicting these damage indicators and specific information can be found

42 American Meteorological Society, Glossary of Meteorology 2nd Edition. Available online at http://amsglossary.allenpress.com/glossary last accessed on February 11, 2009. 43 National Severe Storms Laboratory “FAQ About Tornados.” Available online at http://www.nssl.noaa.gov/faq/faq_tor.php last accessed on February 11, 2009. 44 Ibid.


on the National Weather Service website at http://www.spc.noaa.gov/faq/tornado/ef-scale.html.

A table showing the relationship between the original Fujita Scale and the Operational EF Scale, which was enacted as the standard measurement system in the United States beginning February 1, 2007, is presented in Table 4.32.

Table 4.32 Fujita and Enhance Fujita Scale

Fujita Scale Derived EF Scale Operational EF Scale

F Number

Fastest 1/4-mile (mph)

3 Second Gust (mph) EF Number 3 Second Gust

(mph) EF Number 3 Second Gust (mph)

0 40-72 45-78 0 65-85 0 65-85

1 73-112 79-117 1 86-109 1 86-110

2 113-157 118-161 2 110-137 2 111-135

3 158-207 162-209 3 138-167 3 136-165

4 208-260 210-261 4 168-199 4 166-200

5 261-318 262-317 5 200-234 5 Over 200 Source: National Weather Service. Available online at http://www.spc.noaa.gov/faq/tornado/ef-scale.html

Geographic Extent

Tornados are documented across Wisconsin, as demonstrated in Figure 4.27 Dane County currently has more reported tornado events than any other county in Wisconsin for the period of 1982-2008. This is partially due to the fact that Dane County is a large county– the larger the county the greater the chances that a tornado will occur within its boundaries. However, Southern Wisconsin tends to experience more tornadoes than northern Wisconsin since it is closer to the storm track that pulls warm and moist air up from the Gulf of Mexico. Warm, moist air is the fuel for thunderstorm development.

Figure 4.28 shows the tornado paths or, for short-duration events, the tornado touch-down points. This figure indicates that tornados occur in any portion of the county and often cross county lines. As any portion of Dane County is vulnerable to a tornado, the associated geographic extent is extensive. Despite this overall possibility of tornados, a single tornado does not impact the entire county simultaneously and damages less than five percent of the total county area in any given event (an extreme example: a 1-mile wide tornado going northeast along the 51-mile diagonal of Dane County would damage 51 square miles, or only 4.2% of the total county area). This rates between a limited and significant extent rating, based on the size of the tornado. Averaging these two considerations together, the overall geographic extent of tornados for Dane County is significant.


Between 1844 and 2008, 67 tornadoes of varying intensities have been recorded in Dane County. In fact, more tornadoes have occurred in Dane County than any other county in the State. The vast majority of tornadoes recorded had intensities classified as F0-F2. The NCDC database has recorded 48 tornados over the past 53 years. Of these, 12 events were rated as F2 tornados and four events were classified as F3 tornados. While the NCDC database has no higher records than an F3 for Dane County, Figure 4.28 indicates at least one F5 tornado occurred during this time period. Further research indicates the tornado was actually an F2 when it entered Dane County. This tornado reached F5 intensity just to the


west in the Barneveld area of Eastern Iowa County. Dane County has received one state disaster declaration and four presidential disaster declarations since 1971 for tornados.45

Past tornadoes in Dane County have traveled as little as a tenth of a mile, but have gone on for as many as 36 miles. Tornadoes have passed through numerous populated areas, such as the City of Sun Prairie, Village of DeForest, Village of Black Earth, the City of Monona, the City of Stoughton, and the City of Madison

45 Wisconsin Emergency Management “County Disasters Since 1971.” Available online at http://emergencymanagement.wi.gov/sublink.asp?linksubcat2id=38&linksubcatid=87&linkcatid=40&linkid=30&locid=18 last accessed on February 11, 2009.


Figure 4.27 Tornado Events in Wisconsin by County



Figure 4.28 Tornado Incidents and Paths for Dane County (1950 – 2008)


Data from the National Weather Service (NWS), indicates that more tornadoes have affected Dane County in the past five decades, as compared to previous decades. However, much of this increase is due to greater documentation efforts by NWS meteorologists, especially from the 1980s to the present. Prior to the 1960s, unless a tornado struck Main Street in broad daylight, it likely went undocumented.

Additionally, severe weather spotter and research videotapes of tornadoes in the past 20 years has shown that a tornado can be in progress, but a visible “funnel cloud” may be absent or poorly defined. In these cases, confirmation of a tornado is based on a rotating dirt/debris spray observed at ground and cloud-base rotation directly above.46

In more recent years, the National Weather Service and the National Climatic Data Center (NCDC) have been tracking weather extremes and their consequences in greater detail. A search of the NCDC website provided the following descriptions of several tornados from the past twenty years:

June 1984

At approximately 12:41 am the 8th of June an F5 Tornado touched down in neighboring Iowa County, leveling Barneveld, a village of over 600 people. One of the few structures left standing was the water tower. The Barneveld Tornado remained on the ground throughout its entire 36-mile journey. Additionally, the path of the tornado’s destruction was exceptionally wide, at times 300 yards.

Soon after touching down in Barneveld, the tornado headed on a northeast path into Dane County. The path of the tornado went through the Town of Vermont and through the Village of Black Earth, and the NCDC records indicate the Tornado had dissipated to F2 intensity by that time. The records from the Town of Vermont were not available to verify this at the time of the 2009 update. Twenty-four homes were damaged and at least 8 were destroyed. Woodlots were plucked clean of foliage and branches, and some trees were uprooted from the ground. Once the tornado dispersed, nine people were left dead (all in Barneveld) and about 200 were left injured as a direct result of the storm. Total damages exceeded $66.3 million. Dane County damages totaled approximately $4.1 million. Dane County received a Presidential Disaster Declaration to assist with recovery costs from this storm.

The Town of Vermont offers these thoughts in their data collection guide: “Occurring in 1984, and known as the Barneveld Tornado, it skipped diagonally through the Town of Vermont. It damaged and destroyed a number of homes and farm buildings. There was considerable road blockage from fallen trees and crop destruction both from the wind and from debris in the fields.”

September 1992

On June 17 at 12:06 pm, an F3 tornado struck Dane County. The tornado first touched down in the Village of Belleville, about 15 miles south of the City of Madison, and began its trek northeast touching down just east of Highway 69 damaging farm structures and killing livestock. It then headed into the City of Fitchburg leveling a subdivision (18 homes total) severely damaging the Oregon Correctional Facility, destroying 20 buildings. The tornado also did damage in the Town of Dunn, destroying numerous homes. Although no deaths were reported approximately 30 people sustained injury. An estimated 201 homes were

46 National Weather Service Milwaukee-Sullivan, 2009


damaged totaling $30.6 million in losses. Damages are estimated at 30 homes destroyed, 34 with heavy damage, 29 with medium damage, and more than 130 incurred minor damage. Dane County received a Presidential Disaster Declaration to assist with recovery costs from this storm.

August 18, 2005

A strong and destructive tornado spun up at 1715CST about 2.8 miles southeast of the geographic center of Fitchburg (or 2.0 miles north of center of Oregon), about 400 yards southwest of the intersection of CTH MM and Schnieder Rd. It continued east-southeast to the southern edge of Lake Kegonsa and tore through residential neighborhoods about 1/3 to 1/2 mile north of the towns of Dunn and Pleasant Springs, and far-northern Stoughton. It moved with Interstate 90/39, and stayed close to CTH A to its exit point at 1905CST where CTH A crosses into Jefferson County, about 2.8 miles south-southwest of Rockdale.

One person was crushed to death in their basement from fireplace and chimney bricks that crashed through the floor. Twenty-three (23) other people were directly injured. In addition, Emergency Management officials received reports of 2 other indirectly-related deaths associated with this strong tornado. In these two cases, the people were already very ill or suffering from a life-ending disease. Injuries they received during the tornado contributed (secondary) to their death, but were not the primary cause of death, based on medical examiner reports. Consequently, these additional two deaths do not appear in the official death tally in the header strip of this event. Numerous homes, businesses, farm buildings, vehicles, power-lines, trees, and other personal effects were either damaged or destroyed along its path that grew to a maximum width of about 600 yards north of Stoughton. As for residential structures, 220 sustained minor damage, 84 had major damage, and 69 were destroyed. As for business structures, 6 sustained minor damage, 1 had major damage, and 1 was destroyed. As for agricultural structures, 5 sustained minor damage, 5 had major damage, and 40 were destroyed. The overall slow movement (the supercell moved at 12-17 knots, or 10-15 mph), coupled with structures that were not thoroughly reinforced (based on NWS damage survey), allowed the tornado's cyclonic winds to more severely damage buildings in its path. Consequently, although some of the worst damage resembled what would be left by a F4 tornado for well-built homes, this tornado was rated at the top of the F3 category with estimated winds near 174 knots (200 mph).

Total estimated damage amounts (directly-related) for private and public sectors combined was $35.06 M, broken down to $34.31 million in property damage and $750,000 in crop losses, for the tornado segment in Dane County. The $34.31million in property damage was broken down to private losses (total of $32.29 million) and public losses (total of $2.02 million), per Emergency Manager reports and NWS estimates. The private losses included a total of $25.45 million for residential structures; $1.29 million for businesses; $4.25 million for agricultural structures; $1 million for damage to vehicles, boats, and other personal effects; $200,000 to agricultural machinery and tools; and $96,000 in public road system damage. The public losses making up part of the $34.31 M consisted of $2.02 M in damage to public utility systems. The $750,000 in damage attributed to crop losses occurred on an estimated 1,550 acres of land. Additional monetary costs incurred in the public sector (totaling $1.84 million) which are considered indirectly-related damage expenses, and not included in the "direct" totals listed in the header-strip of this event, include: $1.38 million in debris clearance; $308,000 in protective measures; and miscellaneous damage/expenses of $144,000. Therefore, the grand total of direct and indirect damage amounts and expenses attributed to this tornado segment in Dane county totaled about $36.89 million. The State Disaster Fund provided relief aid for this disaster. The Stoughton Attachment has additional specifics on impacts to the City of Stoughton.


In addition to this tornado, a minor F0 tornado developed approximately 2 miles west-southwest of the Village of Dane, and traveled northeast, ending 0.8 miles north of Dane. Some crop damage was reported, but the overall rating was an F0. Another tornado developed just north of the F3 Stoughton tornado bath, about 1.6 miles south-southwest of Rockdale. Many large trees were uprooted or twisted and minor damage was inflicted on three homes and one pole shed, in addition to knocking down power lines. This tornado was rated an F1 with estimated winds of 64-79 knots (73-112 mph) and the average path width was about 50 yards. This was part of the largest single-day tornado outbreak in Wisconsin recorded history for south-central and southeast Wisconsin. A total of sixteen tornadoes were documented on this day.

June 7, 2008

This tornado moved from just west of Hults Road on the far western part of Stoughton northeast to a point northwest of the intersection of CTH B and CTH N. Based on the observed damage, it was probably a multiple-vortex tornado. In the Stoughton area, with respect to residential homes, it resulted in very minor damage to 24 homes, minor damage to 21 homes, and major damage to 3 homes. Additionally, 1 church sustained major damage, and 1 tobacco shed was destroyed. Total estimated property damage (roofs, siding, walls, windows) in the Stoughton area was $409,000.

June 12, 2008

This tornado in south-central Dane County was a continuation of a tornado that spun up mid-way between the city of New Glarus and the village of Postville in northwest Green County. It entered Dane County on the west side of the City of Belleville and then moved northeast through the Lake Belle View area and crossed STH 69 about 1 mile north of the County Line, and ultimately dissipated southeast of Basco, near CTH A. Luckily only tree damage occurred - of the uprooted tree or broken tree branch variety. Wind speed estimated at 83-87 knots (95-100 mph). The average path width in Dane County was about 60 yards.


Tornados are reported in Dane County nearly every year. Using the formula established in Section 4.2.1 Profile Methodology, the assessment reflects (49 events over [divide by] 53 years) x 100 = 92 percent chance of occurrence and a likely occurrence rating. This information is drawn from the NCDC database and was current as of February 2009.

Impact Assessment

The National Weather Service considers tornadoes to be among nature’s most violent storms. The most violent tornadoes are capable of tremendous destruction with wind speeds of 250 mph or more. Tornadic winds can cause people and autos to become airborne, rip ordinary homes to shreds, and turn broken glass and other debris into lethal missiles. Even weaker tornados can cause large economic damages. For example, a F1 tornado in June 2008 caused $429,000 in damages, while an F3 tornado in August 1967 caused only $25,000. Though the strength of the tornado often dictates the impacts, it is important to remember that the location (rural or uban) of the tornado is just as important when assessing these risks.


Direct Impacts

Directly, tornados impact the physical contents of the County, including structures, crops, and population. Damages caused by the tornado results in large amounts of debris, which may clog transportation networks, create a large population who require shelter or alternative living conditions, and may delay the response of emergency personnel during and after the event, and the arrival of relief supplies and assistance following the event. As with almost all disasters, there are also psychological impacts on the population both directly and indirectly affected by the event which may result in immediate or delayed reactions to the event.

Indirect Impacts

Indirect impacts of tornado include the often large rebuilding costs and timeframes for reconstruction or repair of damaged homes, shops, roadways, or other buildings. When a tornado event impacts a large portion of the community, these impacts may increase in severity as the timeframe of recovery is prolonged. The psychological impact of tornados may indirectly impact the community’s recovery as well. Loss of revenue due to closed and damaged buildings, damaged transportation networks, and delayed employment conditions may also indirectly or directly impact the communities.


The damage to property, essential infrastructure and human life ranges from minimal to catastrophic based on the sporadic nature of the events. The variability of these impacts does not lessen the dangers of the events, however. Based on the worst case magnitudes and severity ratings examined in this profile, the overall rating for tornados in Dane County is catastrophic.


Exposure is measured by the relative effect of tornados on four categories: Population, General Property, Essential Infrastructure, and Natural, Cultural or Historic Resources. Each category is analyzed to reflect the specific and general exposures to the hazard, and assigned a corresponding exposure rating ranging from low to high. The overall exposure assessments are captured by averaging the ratings for each category. For a tornado, the overall exposure assessment for Dane County is medium.

Population

Populations are the most vulnerable to tornados. The availability of sheltered locations such as basements, buildings constructed using tornado-resistant materials and methods, and public storm shelters, all reduce the exposure of the population. However, there are also segments of the population that are especially exposed to the indirect impacts of tornadoes, particularly the loss of electrical power. These populations include the elderly or disabled, especially those with medical needs and treatments dependant on electricity. Nursing homes, Community Based Residential Facilities, and other special needs housing facilities are also vulnerable if electrical outages are prolonged, since backup power generally operates only minimal functions for a short period of time. The Dane County capacity counts for these facilities indicate 15,827 exposed people just within documented, licensed care centers. Approximately 10 percent of the population over the age of 5 is disabled in some way, and 35 percent of the population is considered exposed due to age, either under the age of 18 or over the age of 65. These individuals may have difficulty reaching shelter in


time without assistance, or may be concentrated in large groups, such as day care centers, which require additional time to safely shelter all occupants. The estimated 11 percent of the population that lives below the poverty line are also exposed as they may not have access to adequate shelters. Overall, the vulnerability of the population to tornados is medium.

General Property

General damages are both direct (what the tornado physically destroys) and indirect, which focuses on additional costs, damages and losses attributed to secondary hazards spawned by the tornado or due to the damages caused by the tornado. Depending on size of the tornado and the length of time a property is exposed to the event, a tornado is capable of damaging and eventually destroying almost anything. Construction practices can help maximize the resistance of the structures to damage, but it is difficult to project these impacts into general vulnerability assessments because of the variability of the construction uses. Table 4.33 lists the total parcel counts and values for the property in Dane County. Property is considered to have a medium vulnerability rating to tornados.


Secondary impacts of tornado damage often result from damage to infrastructure. Downed power and communications transmission lines, coupled with disruptions to transportation, create difficulties in reporting and responding to emergencies. These indirect impacts of a tornado put tremendous strain on a community. In the immediate aftermath, the focus is on emergency services. Law enforcement activities focus on scene security. Fire and EMS personnel rescue the injured, put out any fires caused by broken gas lines or other similar hazards and assist in the clean up. Utility crews restore power, phone and other utility services. Highway and public works crews remove debris from roadways. Victims and their insurance agents need access to the properties to assess the damage and search for valuables or heirlooms. The overall vulnerability of essential infrastructure is medium.


Just as any property, infrastructure, or population is vulnerable to a tornado, any natural, cultural or historic resource in the path of a tornado event is impacted. Direct impacts are combination of the structural damages discussed in General Property, the exposures of the population frequenting the resource, and the additional dimension of potentially irreplaceable losses if artifacts, artwork, historical documents, and other cultural resources are destroyed. Large community resources which may serve as shelters in the aftermath of a disaster are also vulnerable, and any sustained damages or losses to them may impact the ability of the community to recuperate from the disaster. The overall vulnerability of these resources is medium.

Estimating Potential Losses


The potential for future losses due to tornado damage is estimated based on an extrapolation of losses from past events. There are limitations to this method:

• Every tornado is unique in location, duration, and intensity. It is impossible to predict with any degree of certainty where and when a tornado will strike. As a result, the risk of tornado occurrence is essentially uniform, countywide.


• The exposure to damage increases as the population of the County increases. Future damages may increase simply due an increase in the amount of exposed property. This method of estimation cannot account for increasing risk due to growth.

• Indirect impacts are not well accounted for. • The damages resulting from a tornado depend greatly on where and when the storm

hits. A severe tornado tracking through an undeveloped area may cause less damage than a weak tornado striking an urban or residential area.

While the estimation of future losses based on past events is unsophisticated, it still is a useful method of quantifying the damage potential. The following assumptions were made for this estimation:

• Based on NWS data in GIS format developed by Geographic Techniques, spanning the time period of 1955 to 2008, the average tornado in Dane County is 6.2 miles long and 104 yards wide, and remains on the ground for an average of 7.5 minutes. Average affected area by a tornado equals 540 acres.

• The average intensity is F2. • Residential, commercial, and manufacturing and agricultural properties are evenly

distributed across the County. • The Fujita Scale was designed with a "well-constructed" frame house as the standard for

assessing failures in building construction. Due to the variability in the quality of construction and other factors, some buildings may experience less or more damage than others when exposed to F2 category wind speeds.

In addition to structural damage, building contents and personal property will also be damaged or destroyed as a result of a tornado. Approximations of the value of building contents are based on the FEMA estimates collected in Table 4.33. To account for the variations in construction and the actual distribution of residential, commercial, and manufacturing properties, a range of damage potentials, as collected in Table 4.33 were used. Calculations performed using these tables are presented as an average, with site-specific variations expected, but not easily quantified. They provide an "average expectation" or "typical impact".

Table 4.33 Average Loss Expected By Fujita Damage Scale

Fujita Scale Damage Description Percentage of Structure and

Building Contents Value Lost due to Damage

F1 Moderate Damage. Roof surface peeled off; window breakage; attached garages may be destroyed. 0% to 20%

F2 Considerable damage. Roofs torn off frame houses; light object missiles generated. 50% to 100%

F3 Severe Damage. Roof and some walls torn off well constructed houses. 100%

F4 and above Devastating Damage. Well-constructed houses leveled; structures with weak foundations blown off some distance; large missiles generated.

100%

Source: Dane County Emergency Management.

In order to calculate the property damaged by the average tornado, the number of residences, commercial and manufacturing structures, and acres or crops affected by the area of the average tornado was determined for each municipality and the County. The average tornado area was divided by each municipality’s area, resulting in a percent of area


impacted, or affected area. Multiplying the improved value plus content value of all structures by the percent affected area yields the exposure of affected property. Multiplying the affected area by the number of improved parcels yields an estimate of the number of structures impacted. Final loss ranges are calculated by multiplying the exposed property value by 50 percent for the low and 100 percent for the high, based on the average impacts in Table 4.33. A low damage estimate was calculated using a value of 25 percent of the exposed property value. The expected losses from this average tornado, by jurisdiction, can be referenced in each jurisdictional annex. A summary table by jurisdiction is provided in Table 4.34, sorted by loss ratio. The loss ratio analysis was conducted on the moderate damage range. The loss ratio is the estimated loss divided by the total exposed value. The higher the ratio, the more difficult it would be for the community to recover from the event.

Table 4.34 Tornado Loss Estimate by Jurisdiction

Participating Municipality

% area of jurisdiction impacted


Affected Structure Estimate

Total Exposed Value ($)

Estimated Loss $ (High

Damage Range)

Estimated Loss $

(Moderate Damage Range)

Estimated Loss $ (Low

Damage Range)

Loss Ratio for

Moderate Damage Range

City of Edgerton

100.00% 22 22 37,780,700 37,780,700 18,890,350 4,722,588 50.0%

City of Fitchburg

2.40% 6,286 151 2,759,335,500 66,224,106 33,112,053 8,278,013 1.2%

City of Madison

1.09% 53,596 585 22,885,068,300 249,953,412 124,976,706 31,244,176 0.5%

City of Middleton

10.06% 5,615 565 2,830,137,875 284,848,730 142,424,365 35,606,091 5.0%

City of Monona

25.71% 2,825 726 1,184,532,400 304,529,352 152,264,676 38,066,169 12.9%

City of Stoughton

16.58% 4,161 690 1,181,541,000 195,926,345 97,963,173 24,490,793 8.3%

City of Verona 13.86% 3,527 489 1,650,962,100 228,759,697 114,379,849 28,594,962 6.9%

Village of Belleville

53.47% 723 387 186,536,250 99,736,161 49,868,080 12,467,020 26.7%

Village of Blue Mounds

96.32% 238 229 63,233,200 60,907,397 30,453,699 7,613,425 48.2%

Village of Brooklyn

100.00% 319 319 62,047,150 62,047,150 31,023,575 7,755,894 50.0%

Village of Cambridge

66.70% 550 367 166,303,600 110,931,419 55,465,709 13,866,427 33.4%

Village of Cottage Grove

25.90% 1,917 497 604,462,500 156,560,607 78,280,304 19,570,076 13.0%

Village of Cross Plains

52.81% 1,248 659 338,624,700 178,831,822 89,415,911 22,353,978 26.4%

Village of Dane

73.72% 339 250 83,862,150 61,823,593 30,911,796 7,727,949 36.9%

Village of Deerfield

39.14% 869 340 181,322,050 70,969,841 35,484,921 8,871,230 19.6%

Village of DeForest

11.23% 2,822 317 978,518,750 109,907,744 54,953,872 13,738,468 5.6%

Village of Maple Bluff

100.00% 547 547 247,996,300 247,996,300 123,998,150 30,999,538 50.0%

Village of Marshall

36.90% 1,003 370 226,221,250 83,479,844 41,739,922 10,434,981 18.5%








Damage Range)

Estimated Loss $



Damage Range)

Loss Ratio for


Village of McFarland

24.28% 2,579 626 824,863,500 200,237,139 100,118,569 25,029,642 12.1%

Village of Mount Horeb

26.50% 2,232 591 592,647,100 157,023,479 78,511,740 19,627,935 13.2%

Village of Oregon

19.43% 3,163 615 969,588,750 188,425,977 94,212,988 23,553,247 9.7%

Village of Shorewood Hills

100.00% 659 659 403,176,913 403,176,913 201,588,457 50,397,114 50.0%

Village of Waunakee

13.52% 3,766 509 1,365,293,900 184,569,214 92,284,607 23,071,152 6.8%

Town of Albion

2.38% 1,004 24 213,759,700 5,090,343 2,545,172 636,293 1.2%

Town of Berry 2.35% 511 12 132,225,200 3,112,552 1,556,276 389,069 1.2%

Town of Bristol

2.49% 1,301 32 421,555,850 10,507,137 5,253,569 1,313,392 1.2%

Town of Cottage Grove

2.60% 1,503 39 353,983,950 9,215,822 4,607,911 1,151,978 1.3%

Town of Dunn 2.98% 2,089 62 501,704,250 14,926,184 7,463,092 1,865,773 1.5%

Town of Madison

56.49% 1,271 718 423,044,150 238,968,604 119,484,302 29,871,075 28.2%

Town of Middleton

5.30% 2,066 110 1,055,298,735 55,974,540 27,987,270 6,996,817 2.7%

Town of Montrose

2.47% 476 12 103,592,850 2,563,049 1,281,524 320,381 1.2%

Town of Oregon

2.71% 1,199 33 398,894,100 10,827,402 5,413,701 1,353,425 1.4%

Town of Pleasant Springs

2.53% 1,377 35 440,400,850 11,136,695 5,568,348 1,392,087 1.3%

Town of Primrose

2.36% 305 7 71,708,150 1,690,190 845,095 211,274 1.2%

Town of Roxbury

2.35% 702 17 183,212,650 4,308,941 2,154,470 538,618 1.2%

Town of Rutland

2.38% 821 20 239,744,400 5,702,623 2,851,311 712,828 1.2%

Town of Springdale

2.39% 759 18 285,520,800 6,813,359 3,406,679 851,670 1.2%

Town of Springfield

2.33% 979 23 356,884,100 8,331,334 4,165,667 1,041,417 1.2%

Town of Sun Prairie

2.80% 877 25 258,724,600 7,232,855 3,616,427 904,107 1.4%

Town of Vermont

2.35% 385 9 115,530,800 2,719,717 1,359,859 339,965 1.2%

Town of Verona

3.38% 720 24 253,634,825 8,569,798 4,284,899 1,071,225 1.7%

Town of Vienna

2.38% 588 14 207,592,850 4,937,752 2,468,876 617,219 1.2%

Town of 3.81% 1,586 60 646,879,150 24,618,753 12,309,377 3,077,344 1.9%








Damage Range)

Estimated Loss $



Damage Range)

Loss Ratio for


Westport

Town of Windsor

2.95% 2,155 63 566,987,250 16,704,774 8,352,387 2,088,097 1.5%

Using these estimations, the damage potential range for an F2 tornado with an average track length of 6.2 miles and width of 104 yards is between $845,000 and $201 million for the moderate damage range, depending on what jurisdiction is impacted. The average of this range is $47 million. This includes only losses directly due to the tornado’s destruction. Government emergency response and recovery costs and indirect impacts are not included in this figure.

The event of record is the 2005 Stoughton tornado, which caused a total estimated damage amount of $36.89 million. The entire documented costs of damages in Dane County caused by tornados, between the spring of 1955 and the summer of 2008, is approximately $70 million. Assuming this total cost can be spread evenly over the 49 documented events in the NCDC database, the average cost of a tornado is $1.4 million. Losses could be much higher, depending on where the tornado occurs.

Development Trends

The exposure to tornados will increase as growth and development trends continue in the County. Tornado-resistant construction can lower the exposure of population, and potentially reduce property damage costs. Integrating tornado shelters/safe rooms into new development can help reduce the exposed population. The potential alteration of the landscape (such as leveling previously hilly land for development) may have an impact on the severity of tornado damage, although there is not currently scientific information to support this theory. Dane County’s population is expected to age as the “Baby Boomer” trend continues forward, therefore increasing these potentially vulnerable populations due both to age and living conditions.


Dane County has the highest number of reported tornados in the state. Tornado damages recorded on the NCDC database from the spring of 1955 through the summer of 2008 totaled approximately $70 million, making it one of the most costly natural hazards to impact Dane County. Only Flooding (with an estimated $385 million in damage from 1996 to 2008 reported to NCDC) and Winter Storms (with an estimated $135 million in damages reported) have more catastrophic fiscal impacts in a consistently quantifiable form. Tornadic winds primarily damage structures, though crop losses have occurred. Since the mid-1800s, only four people have died from tornadoes in Dane County, but 66 have sustained injury. Based on these past impacts, and the potential for future tornado losses and loss of life, the overall risk rating is considered high. Table 4.35 provides the summary of all aspects of the hazard profile that were evaluated to establish an overall hazard rating.


Table 4.35 Overall Risk for Tornados


Geographic Extent Significant 3.0

Probability of Future Occurrence Likely 3.0

Exposure Assessment Medium 3.0

Impact Magnitude and Severity Catastrophic 4.0


4.2.13 Wildfire

Description

Wildfire is any free burning and (at one time) out of control forest fire, grassland fire, rangeland fire, or urban-interface fire which consumes the natural fuels and spreads in response to its environment. While often considered as a destructive force, wildfires also play a positive role in nature by clearing underbrush, controlling insect populations, and depositing nutrients into the soil. Many plant species have evolved to cope with and take advantage of wildfires. Periodic, spatially-interrupted burn patterns lead to higher species diversity and healthier ecosystems. Unfortunately, when wildfires ignite in altered ecosystems (such as housing developments), the intensity, duration, and spread of the fire also change. Wildfire becomes a destructive force for ecosystems, resulting in heightened erosion conditions and other damages to the environment, in addition to the property damages sustained by human developments.

Certain conditions must be present for wild fires to take hold. The most common conditions include:

• Hot, dry, and windy weather; • Inability of the fire service to contain or suppress the fire; • Occurrence of multiple fires that overwhelm local resources; and • Large fuel load.

Once a fire has started, additional conditions will influence its behavior, including topography and land-use patterns.

The vast majority of wildfires in Dane County are human-caused. Wildfires initiated by lightning are very rare. When wildfires do occur in Dane County it is also very rare that a home or business is lost. Wildfires are most common in the spring when brush is still brown and dry.

Geographic Extent

Historically, the County contained fire-maintained plant communities such as prairies, oak savannas, oak or pine barrens, and oak woodlands. Fire occurrences ranged from annually to about once a decade. North facing slopes and areas with natural firebreaks (north and east of lakes and rivers) burned less frequently. The fires were frequent and burned lightly enough in the oak areas to prevent the death of mature, thick-barked trees. The jack pine areas usually experienced more severe, stand-killing crown fires which occurred less frequently than the oak and prairie fires. Current natural fire patterns are altered though


deliberate fire suppression actions and the introduction of fuel breaks such as roads, developed areas and agricultural fields.

Most of the County is managed under a cooperative fire management program overseen by individual fire districts. The northwestern portion of the County is under state jurisdiction and classified as an “extensive fire area”, and includes the jurisdictions of the Towns of Roxbury, Vermont, Black Earth, Mazomanie, and Berry and the Village of Mazomanie. A portion of the Town of Blue Mounds is also included. In cooperative areas, data on wildfires is sparse and unorganized, which makes it essentially unavailable. Most of the data used in this assessment is derived from land under state jurisdiction for fighting wildfires. The ecology of the county lends itself to natural defenses from wildfires. Much of the county is covered by water or wetlands, or well developed with fire breaks. Less than 10 percent of the land in the county is expected to be impacted by wild land fires, making the geographic extent rating limited.


From 1974 to 1998 Dane County has experienced 173 fires in the state managed extensive fire area, or about 7 fires a year. Many of the fires are smaller than an acre due to the number of roads that act as firebreaks and allow for fast response times by fire departments. For example, in the first three months of 2008, the Dodgeville Department of Natural Resources Dispatch Group, which includes only the north-western most portion of Dane County, experienced 24 fires with a total of 113.13 acres burned, for an average fire size of only 5.5 acres.47 Table 4.36 lists the documented wildfire incidents in Dane County that had fire areas greater than or equal to 10 acres.

Table 4.36 County Wildfires =>10 acres 1974-2003

Acres Year Month Day Cause Permit COST

10.0 1975 October 05 Unknown No $ 370

10.0 1977 April 16 Large Burn Yes $ 219

16.0 1980 April 18 Truck Not Needed $ 195

56.0 1980 April 16 Large Burn No $ 171

13.0 1980 May 03 Large Burn No $ 225

23.0 1984 March 02 Hike Not Needed $ 92

14.4 1987 March 24 Slash Yes $ 383

53.0 1992 March 19 Brush No $ 542

18.0 1994 March 20 Trash No $ 468

30.0 1994 March 31 Large Burn Yes $ 1,465

500 2003 April 27 Unknown Unknown Unknown

110 2003 March 23 Unknown Unknown Unknown Source: Wisconsin Department of Natural Resources

In 2003 there were two relatively large wildfires outside of the state managed area, the Deansville marsh fire that took place on April 27, 2003 and burned 500 acres, and the Town of Dunn marsh fire on March 23, 2003, which burned 110 acres. Though these fires were

47 Wisconsin Department of Natural Resources, “Forest Fire Program Fire Report Website”. Available online at http://dnr.wi.gov/forestry/fire/Fire_Danger/fire_report.asp, accessed on March 23, 2009.


large, they posed little threat to life and property. Even within the context of recent fires, the chance of structural damage due to wildfire is extremely small. Available data shows that very few structures have ever been lost due to wildfires in the County. Relatively easy accessibility to fires and low fuel loads has likely provided first responders with an advantage in combating the blaze.

Relying on wildfire data in the intensive fire areas of the County shown in Table 4.33, the average size of large fires (that is, fires encompassing at least 10 acres) is 71 acres and the average cost of response is approximately $450. These numbers give an indication that wildfire does not currently pose a significant threat to the safety of citizens and property in the County.


Based on the available data between 1975 and 2003, the assessment reflects wildfires 10 acres or more have a 42.9 percent (12 events over [divide by] 28 years) x 100) chance of occurrence and a likely occurrence rating. Smaller fires happen every year.

Impact Assessments

Direct Impacts

Directly, fire endangers property and lives when it burns in an uncontrolled or unexpected manner. Fire is particularly dangerous when it encroaches into urban areas, or when it moves faster than fire suppression technology can cope. Sometimes, wildfires can exceed the warning time and evacuation capabilities of the population which greatly increases the direct impact on human life. Wildfires also exhibit a number of positive direct impacts, mostly connected to the continued renewal of a healthy ecological balance in natural areas. However, according to the Wisconsin Department of Natural Resources, almost all fires in Wisconsin are started by humans and are not, therefore, part of the natural ecologic process.

Indirect Impacts

Indirectly, wildfires create a significant drain on resources and manpower, as large fires are extremely complicated, require large commitments of resources and personnel, and may cause extensive personal and property damage. Historic fires in Wisconsin have wiped out entire communities (such as the city of Marshfield in 1887). While such fires are considered unlikely, the potential economic impact of wildfire on the state is enormous. These impacts cross County lines as well, by requiring the allocation and loan of resources across standard jurisdictional boundaries, sometimes even requiring national response support.


The size of wildfires in Dane County range from approximately 500 acres to a fraction of acre, most fires cover about 3 acres. Woodland and open lands, land that has the potential for wildfire, make up about 22 percent of the total acreage in the County. Much of Dane County is agricultural or urban land. How a fire will burn within the natural areas of the County is a complex phenomenon affected by wind, air temperature, humidity, fuel loads, fuel moisture, and topography.

In densely wooded areas fires could destroy much in their path, fueled by high winds and high fuel loads. Other fires, such as those that might occur in a prairie ecosystem, burn


cooler along the ground and leave a dappled pattern of untouched areas within burnt areas. Fire prediction, though greatly aided by the development of new computer modeling programs, remains an imprecise science.

Wildfire is also destructive when it interfaces with urban areas. Wildfire-vulnerable structures in Dane County are rare and the cost of fighting wildfires generally runs in the hundreds of dollars per response. Based on these assessments the overall impact magnitude and severity rating is considered minor.


There are very few areas of the County where conditions indicate a high vulnerability to wildfires. Areas of higher relative vulnerability to wildfires are those in the urban/wildland interface, including:

• Areas where urban and suburban development is adjacent to open expanses of wild land areas.

• Mixed urban interface where isolated homes, subdivisions, or small communities are situated in predominantly wild land settings.

• Wild land/urban interface where islands of wild land vegetation occur inside a largely urban area.

• Areas that are hilly also can burn more readily. Fires run up hills igniting fuels more easily than on flat ground.

Population

The most exposed population are those living in the wildland-urban interface (WUI) zones, where residential properties are directly intruding into traditional wildland areas. The exposure of the population in these zones increases with the exposure of the corresponding general property, examined in the section below. Other exposed groups include children, the elderly, or those with breathing conditions who may be exposed to high levels of smoke. Approximately 35 percent of the County’s population is exposed to the effects of wildfire due to age conditions alone. Populations living in long term care facilities or other skilled care facilities face additional exposures because of increased evacuation times and the potential that the population may be required to shelter in place. There are 15,827 licensed beds for hospitals, clinics, skilled care facilities, and other group homes or care locations that could be exposed to wildfire. These numbers represent the entire population exposure for the County, however, and a wildfire will only impact a selection of these numbers at any given time. Details on these figures can be found in Section 4.3 Vulnerability Summary. Overall, the vulnerability of the population to wildfires is low.

General Property

Any flammable materials are vulnerable during a wildfire, including structures and personal property. The vulnerability of general property increases as the distance of the property to wildfire-prone areas decreases, and is particularly high for structures located in the WUI. These structures receive an even higher level of vulnerability if the properties surrounding them are not properly mitigated for fire. Appropriate mitigation techniques include using non-flammable materials such as concrete for construction, leaving appropriate spaces between buildings and vegetation areas filled with non-flammable materials (such as decorative rock or stone), and clearing of underbrush and trees. However, the majority of general property is not located in these WUI zones and therefore experiences a minimal exposure to the hazard. If a wildland fire were to cross completely into an urban zone, the


damage would be extensive and there would likely be a higher exposure of property, but the geography and natural climate of Dane County make this event unlikely at this time. Overall, the exposure of general property in the County is low.


These aspects of the County may be exposed directly or indirectly to wildfire. Direct exposures are similar to those of General Property and increase as the infrastructure or facilities and capabilities moves into the WUI zone. Communications lines passing through susceptible areas such as forests are more exposed than those located in cities and other more urban areas. The indirect exposure of response capability increases seasonally and with the number of occurrences. Though the populations making up the response capability are not directly exposed to all fire events, the response of some of the personnel to an event lessens the capabilities overall for response to other emergency situations. If there is a large increase in the number of simultaneous wildland fires, even small ones, the response capability of the County could easily be compromised. This is not considered likely, however, and the overall vulnerability rating is low.


Some natural resources and natural areas may benefit from wildland fire, as at some level they must also be exposed to wildfire for a healthy ecological development of the area. Historic and cultural resources exhibit a vulnerability rating similar to those in general property, where vulnerability ratings increase the further into the WUI the property is, and the less mitigated the landscaping surrounding the property is. In addition, older buildings may be exempt from internal fire mitigation such as sprinklers and fire suppression technology, which may increase the vulnerability of the resource as a total loss once already on fire. Overall, the vulnerability rating is low.



The potential for future damages is estimated by extrapolating data from past events. Future damages are expected to be very similar to past damages, with annual losses due to wildfire ranging in only the hundred’s of dollars. The number of fires and the acres burned between 1974 and 2003 do not indicate that wildfires and their impacts are increasing. This data is limited to areas of the County that is regulated under the state Department of Natural Resources and therefore is a limited data set on which to base loss estimations.

Development Trends

The increasing development of Dane County indicates that encroachment into the WUI is possible. The 2007 Comprehensive Plan notes that density of residential building, which is the primary transgressor into the WUI zone, has increased over the last forty years and is predicted to increase well into 2030. In addition, the plan cites the numerous firebreaks created by roads and other development as a mitigating factor in wildfire events. However, the 2007 Comprehensive Plan also notes that “scattered development patterns tend to fragment the landscape, destroying connections between open areas, creating “edge effects” that increase points of contact between incompatible uses, and creating a variety of cumulative, indirect impacts to natural and agricultural resources. Over time, if cumulative impacts reduce habitat, agricultural areas, or both, below a “critical mass” of contiguous, similar area, the local ecosystem or agricultural economy may collapse. Many of the


policies in Volume I of the Dane County Comprehensive Plan seek to increase residential and commercial density, encourage redevelopment, and promote compact development clustered near existing urban or developed areas as a way of reducing fragmentation.” These policies may aid in minimizing WUI encroachment.


There is limited data indicating that general structures, critical facilities or populations have been or will be harmed by wildfire in the County. While the potential exists for damaging wildfires, many natural and man-made fuel breaks exist. Overall, then, the vulnerability of the County to wildfire is low. Table 4.37 provides the methodology for how all aspects of the hazard profile were evaluated to establish an overall hazard rating.

Table 4.37 Risk Summary for Wildfires


Geographic Extent Limited 1



Impact Magnitude and Severity Minor 1

Overall Risk Rating Low 1.75

4.2.14 Windstorms

Description

Damaging winds occur relatively frequently across Wisconsin, usually in association with severe thunderstorms. While many people immediately associate wind damage with tornadoes, thunderstorm straight-line wind and strong, widespread, non-thunderstorm winds, both up to hurricane force, can result in extensive damage as well. These winds can become hurricane-force in the worst cases. Table 4.37 lists relative wind speeds and anticipated effects. Additionally, Wisconsin experiences another kind of wind damage: non-thunderstorm, widespread “high wind” behind cold-frontal passages in the wake of strong synoptic-scale low pressure systems.

Severe thunderstorms develop powerful updrafts and downdrafts. An updraft of warm, moist air helps to fuel a towering cumulonimbus cloud reaching tens of thousands of feet into the atmosphere. A downdraft of relatively cool, dense air develops as precipitation begins to fall through the cloud. Winds in the downdraft can reach in excess of 87 knots (kts) or 100 miles per hour (mph). When the downdraft reaches the ground it spreads out forming a gust front: the strong, often refreshing wind that kicks up just before the storm hits. As the thunderstorm moves through the area, the full force of the downdraft (called a downburst in strongest cases) in a severe thunderstorm can be felt as horizontal, straight-line winds with speeds well over 44 kts (50 mph). Basically, severe thunderstorms in Wisconsin can produce wind gusts to 50 to 130 knots (58 to 150 mph) per National Weather Service and NCDC data.


Straight-line winds are currents of air in which the ground-relative motion does not have any significant curvature. They are used in the context of surface winds that inflict damage; to be distinguished from winds in tornadoes, which have significant curvature.48 Straight-line winds are often responsible for most of the damage associated with a severe thunderstorm. Damaging straight-line winds occur over a range of scales. At one extreme, a severe single-cell thunderstorm may cause localized damage from a microburst, a severe downdraft extending not more than about two miles across. In contrast, a powerful thunderstorm complex that develops as a squall line can produce damaging winds that carve a path as much as 100 miles wide and 500 miles long.

The non-thunderstorm, widespread “high wind” events usually occur during the cooler part of the year, from October through April. During this time of the year, the atmospheric pressure differences between high pressures and low pressures are maximized. This results in tighter pressure gradients which generates stronger surface winds. These non-thunderstorm “high wind” events usually have wind gusts to 50 to 87 knots (58 to 100 mph) that can persist for 6 to 18 hours over large areas. Severe thunderstorm wind events can inflict considerable damage on trees, power-lines, and other wooden structures.

Strong, widespread, non-thunderstorm winds sometimes affect most of Wisconsin in the wake of a deep low pressure system moving through the Great Lakes region. Meteorologists use the term "High Wind" to describe these situations, which can consist of 10 to 18 hours of steady wind speeds of 30 to 45 mph with occasional gusts to 60 to 100 mph.

Table 4.38 Wind Speeds and Effects

Wind Speed (kts) Wind Speed (mph) Wind Effects

22-27 25-31 Large branches in motion.

28-33 32-38 Whole trees in motion, inconvenience in walking against the wind.

34-47 39-54 Twigs and small branches break off trees, difficulty in walking against the wind, high profile vehicles such as trucks and motor homes may be difficult to control.

48-64 55-74 Potential damage to antenna structures, wind may push over shallow rooted trees, especially if the soil is saturated.

65-83 75-95 Potential for minor structural damage, particularly to manufactured homes, power lines, trees, and signs may be blown down.

84-96 96-110 Moderate structural damage to walls, roofs, and windows, trees blown down, and manufactured homes may be destroyed.

97-113 111-130 Extensive damage to walls, roofs, and windows, trees blown down, moving vehicles pushed off roads.

114-135 131-155 Extreme damage to structures and roofs, trees uprooted or snapped.

Greater than 135 Greater than 155 Catastrophic damage, structures destroyed. Source: National Weather Service Spotters Guidance

Hurricane force winds are defined as a speed equal to or greater than 64 knots (74 mph) or Beaufort Number 12 (Force 12). Hurricane-force winds are not exclusive to hurricanes; they

48 American Meteorological Society, Glossary of Meteorology, 2nd Edition. Available online at http://amsglossary.allenpress.com/glossary last accessed February 11, 2009.


occur quite often in strong non-tropical storms such as the northeaster, or even in severe thunderstorms.49

Geographic Extent

Damaging windstorm events may occur anywhere in Dane County. As with severe thunderstorms, blizzards, hail, or tornados, there are no geographic features within Dane County that naturally lower the risk of a windstorm event. Therefore, the geographic extent rating of the hazard may be considered uniform. However, when damaging wind occurs, it may or may not affect the entire County. Damage associated with a severe thunderstorm tends to be a geographically isolated event, affecting only small areas of several square miles at any one time. On the other hand, widespread, non-thunderstorm high winds can affect much of the county. But since any area of the county can experience damaging windstorms, the geographic extent rating for windstorms is extensive.


The National Climactic Data Center database documented 297 severe thunderstorm wind events in Dane County between 1956 and 2008, or an average of 5.7 events per year. Of these, only 176 documented windspeed, which makes comparative analysis slightly skewed. However, based on the 176 available windspeeds, Dane County has experienced 151 events with windspeeds in excess of 50.4 kts (58 mph), which the National Weather Service defines as a severe thunderstorm wind. 22 events have equaled or exceeded 64 kts (74 mph), which are categorized as hurricane-force winds. The average wind speed during severe thunderstorm wind events, based on this data, is 56 kts (65 mph).

Figure 4.29 indicates the number of severe thunderstorm wind events for Wisconsin, divided by county, from 1982 to 2008. Figure 4.30 identifies the number of events, by county, where thunderstorm wind speeds exceeded 100 mph (87 kts) since 1982. In 1998, a High Winds and Severe Storms disaster was declared in the county, but no state or federal aid declarations were awarded.50

In more recent years, these records have been kept in greater detail, including a description of the event and the resulting impacts. The NCDC database records two, non-thunderstorm high wind deaths for Dane County (one in 1997 and one in 1998), and 2 injuries (1998). The NCDC database also indicates cumulative estimated damage costs of $18.9 million for severe thunderstorm winds and non-thunderstorm high winds. The NCDC website provides the following descriptions of significant high wind events affecting Dane County.

April 6, 1997

Strong gradient winds, enhanced by scattered snow showers (transfer of higher level momentum downward to surface by mixing), resulted in scattered damage reports. In Sun Prairie, the high winds, measured at 66 mph, blew open a glass door in a restaurant. The glass debris struck and injured an elderly woman, who died from the injuries the next day. The Madison TV-3 weather station recorded a peak wind gust of 71 mph at 1715 CST. In the civil Town of Dane, a gust of 61 mph was noted. Southeast of Mount Horeb, the high winds forced the collapse of a barn. A camper vehicle was tipped over on by the powerful winds on

49 Ibid. 50 Wisconsin Emergency Management “Dane County Disasters.” Available online at http://emergencymanagement.wi.gov/sublink.asp?linksubcat2id=38&linksubcatid=87&linkcatid=40&linkid=30&locid=18 last accessed February 11, 2009.


Highway 113. The high winds also toppled large trees in scattered areas across the entire county. One tree in Monona fell against a home and damaged its siding and windows. Power outages were noted. People described the wind-driven debris as "missiles flying through the air."

May 31, 1998

During the early morning hours of Sunday, May 31st, south-central and southeast Wisconsin experienced an unprecedented, widespread downburst wind event known as a "derecho." Incredibly powerful, hurricane-force straight-line winds, with peak gusts of 100 to 128 mph tore through 12 counties in this part of the state, while another 8 counties had peak gusts of 60 to 80 mph. Meteorologically, a solid squall line developed in southern Minnesota and gathered strength as it raced east with a translational speed of 50 to 60 mph across south-central and southeast Wisconsin. The squall line was orientated southwest to northeast and had many microbursts and macrobursts embedded in it. Utility companies and Emergency Managers stated that this was the most damaging, widespread, straight-line thunderstorm wind event to affect southern Wisconsin in the past 100 years. About 60,000 customers were without electricity in south-central Wisconsin, and about 170,000 in southeast Wisconsin. Some residences or businesses were without power for many as 6 days. Hundreds or motor vehicles were damaged or destroyed by falling trees and branches or collapsed garages. Dane County measured gust of 100 mph in Marshall, but peak gusts estimated at 110-120 mph based on damage. The hardest hit areas were Waunakee-DeForest, Sun Prairie, and Marshall. Cars were blown sideways off I-94 north of Madison. Two people injured in Marshall by flying debris as roof was torn off their home. A total of 300 residences had minor damage, 18 major, and 1 was destroyed. One business had minor damage, and 7 had major damage. Twenty farm buildings sustained minor damage, 12 major, and 15 were destroyed.

November 10, 1998

Screaming high winds raked south-central and southeast Wisconsin counties for about 17 hours, resulting in widespread damage to thousands of trees, homes, businesses, power poles, power lines, street lights, road signs, fences, flagpoles, barns, sheds, crops, boats, cars, trucks, campers, trains, airport hangars, and airplanes. Estimated monetary damages were $10.31 million in property damage and $1.625 million in crop damage. The sustained southwesterly winds of 30 to 40 mph gusted to 60 to 70 mph, with isolated gusts to around 80 mph. These relentless winds eventually caused 125,000 customers to lose electrical power. So many poles and lines were toppled that some customers were without power for 3 to 4 days. In Dane County an 87 year-old man was killed after being hit by a car that was blown sideways on the north side of Madison. Several businesses in Madison, Mt. Horeb, and Stoughton sustained damages. In Monona, a roof was torn off a multi-unit apartment building and four other nearby buildings were also damaged. Several dozen semi-trucks were overturned on I-90/94, US-18/151, and US 51 highways.

July 6, 2003

Two rounds of scattered severe convection affected south-central and southeast Wisconsin on Sunday, July 6, 2003. The first round occurred during the morning hours and the second during the late afternoon hours. Powerful, downburst, damaging, straight-line winds toppled large trees and/or power-lines, 4 weak tornadoes spun up, a separate funnel cloud was reported, and there were a couple occurrences of large hail. Detailed descriptions of the four tornadoes can be found in separate reports. Probably the hardest-hit area extended from Middleton (Dane Co.) to Maple Bluff. In the Maple Bluff area, 8 homes sustained minor wind


damage, and toppled trees damaged a car and two boats or large branches during the morning round. Wind gusts in the Maple Bluff area were estimated to briefly reach 65 knots (75 mph). Lightning struck a home in Middleton, resulting in a roof/attic fire.

July 10 2008

Powerful thunderstorm wind gusts toppled large trees and broke branches that brought down some power-lines. In McFarland, a house was blown down, and tree debris damaged a restaurant. Two rounds of severe weather affected south-central and southeast Wisconsin on July 10th. An initial cluster of storms north of the Milwaukee area in Ozaukee County pulsed to severe limits and generated large hail up to 3/4 inch in diameter during the early afternoon hours. A second round of severe weather was associated with several clusters or short bowing segments of lines of storms that moved west to east across southern Wisconsin during the late afternoon and evening hours. Veering winds allowed for the development of rotating updrafts in a couple cells that generated two weak tornadoes. Otherwise, the severe weather type was powerful downburst winds.


Figure 4.29 Severe Thunderstorm Winds by County



Figure 4.30 100 mph+ Thunderstorm Winds by County




Based on the NCDC database (297 severe thunderstorm wind events in Dane County between 1956 and 2008) Dane County has an average of 5.7 severe thunderstorm wind events per year, and equates to a highly likely occurrence rating. The information in the database is incomplete, as not all years have associated wind speed documentation. However, it is rational to assume that events recorded in the NCDC database meet the National Weather Service definition of severe thunderstorm wind event. So, even though actual recorded wind speeds are not available for all events, the entire number of events is recorded here.

Impact Assessments

The relative effects of wind speed are shown in Table 4.35. Past windstorms have caused extensive damage in Dane County. Typical direct and indirect impacts are summarized below.

Direct Impacts

Strong winds associated with severe thunderstorms or other phenomena can cause extensive damage and can result in deaths or injuries. Damage depends on both the wind speed and the nature of the objects in the path of the storm. Strong winds can turn debris and un-tethered objects into missiles. Even heavy vehicles can be rolled over. Homes and large buildings can sustain damage from the direct force of the wind. Broken windows and damaged roofs are common. Falling limbs and trees are also common and can contribute to property damages and downed power lines. Manufactured homes and metal sheds can be destroyed, particularly if they are not fastened to a foundation. Power and communications outages are also common, and storm debris in roads can disrupt transportation and delay emergency response vehicles.

Farm operations can also be heavily impacted by windstorms. Winds can flatten farm crops such as corn and tobacco, and destroy orchard crops such as apples.

Indirect Impacts

The indirect social and economic impacts of wind damage are typically associated with the loss of electrical power. Given our society’s heavy reliance on electric power, any disruption in the supply, even for a short time period, can have significant consequences. The utilities supplying Dane County have worked closely with emergency response agencies and human services providers to develop plans for responding to planned and unplanned power outages in the County. The Dane County Electrical Power Disruption Plan is describes actions to take to mitigate potential indirect impacts.


According to the data presented in Figure 4.29, there have been no casualties caused by severe thunderstorm wind events, and only four injuries (one in 1988, one in 1991, and two in 1998), since 1982. However, the NCDC database records two non-thunderstorm high-wind caused deaths for Dane County (one in 1997 and one in 1998) and no injuries due to non-thunderstorm high-wind events. The NCDC database also indicates a cumulative estimated damages cost of $18.9 million since 1956. The overall magnitude/severity rating is moderate.



As with tornadoes, essentially all Dane County buildings, critical facilities, and populations are vulnerable to windstorm damage.

Population

Some segments of the population are especially vulnerable to the indirect impacts of damaging wind, particularly the loss of electrical power. As a group, the elderly or disabled, especially those with home health care services relying on rely heavily on an uninterrupted source of electricity. Resident populations in nursing homes, Community Based Residential Facilities, or other special needs housing may also be vulnerable if electrical outages are prolonged. Without a back-up power source, rural residents and agricultural operations reliant on electricity for heating, cooling, and water supplies are also especially vulnerable to power outages. Overall, the population vulnerability to windstorm is considered medium.

General Property

In terms of property losses, the actual damages will depend on the building density in the impacted area. This is highly variable across the County. A severe thunderstorm with high winds in an older residential area with older homes, large trees, and overhead utility lines will have a significantly greater impact with the same storm in a new development with lower building density, modern constructed buildings, small or newly planted trees, and underground power lines.

In terms of crop losses, the actual damages that occur will depend on the type of crop and the growth stage of the plants. A wind storm in a rural area in the early spring when the plants are just emerging will have much less of an impact than a storm of the same intensity occurring later in the growing season when the plants are more susceptible to damage and when there is no time to replant if the crop is a total loss. Overall, vulnerability for general property is medium.


Power lines, communications networks, and other above-ground infrastructure are vulnerable to the effects of windstorms both directly and indirectly. The wind itself may damage the infrastructure, or the wind may damage tree branches and throw other debris into the air, which may cause secondary damage to buildings and critical facilities or capabilities. Emergency response vehicles with high profiles may be more exposed to high winds, which may hinder response times. In addition, wind may exacerbate dangerous conditions, such as fires, making response more difficult and dangerous. These are unlikely events but they are severe in occurrence. Overall, these assets have a medium to high vulnerability to windstorms.


Age and construction may impact the vulnerability of cultural or historic resources. Natural resources are vulnerable to damage such as broken or uprooted trees, flattened plant life, or, when wind is combined with extreme heat, severe drying and heightened fire risks. In addition, there is limited means of protecting these resources from wind damage. Overall, the vulnerability of these resources is high.




The potential for future losses due to windstorm damage is estimated based on an extrapolation of losses from past events. There are limitations to this method:

• Every event is unique in location, duration, and intensity. Use of averages does not account for the potential of an extreme event that may occur only very rarely but has severe consequences.

• The exposure to damage increases as the population of the County increases. Future damages may increase simply due an increase in the amount of exposed property. This method of estimation cannot account for increasing risk due to growth.

• Indirect impacts are not well accounted for. • The damages resulting from a windstorm event depend greatly on where and when the

storm hits. A severe storm tracking through an undeveloped area may cause less damage than a weaker storm striking an urban or residential area. Likewise, a severe storm impacting an agricultural area in the early spring will have a very different impact than a storm of comparable intensity over the same area in late summer when the crops are near maturity. Extrapolation from past events does not account well for this variability.

While the estimation of future losses based on past events is unsophisticated, it still is a useful method of quantifying the damage potential. According to the National Weather Service, between 1994 and 2002, losses of more than $200,000 due to windstorms occurred on the following occasions:

Table 4.39 Damaging Windstorms in Dane County 1994 – 2008

Date Property Damage Crop Loss

July 26, 1997 $151,000 N/a

May 31, 1998 $3,100,000 $150,000

June 18, 1998 $208,000 N/a

Nov 10, 1998 $10,400,000 (20 counties) $1,600,000 (20 counties)

June 10, 1999 $200,000 N/a

June 1, 2000 $220,000 N/a

July 2008 $160,000 N/a Source NCDC Website, http://www4.ncdc.noaa.gov/cgi-win/wwcgi.dll?wwevent~storms

The May 31, 1998 non-thunderstorm “high wind” major event is considered the event of record and is used to calculate potential future losses. This number is adjusted for inflation (2008 value) and presented below. The estimated future loss potential from a widespread windstorm at a time when crops are in the ground, but are not mature is:

• Property damage = approximately $4,000,000 • Crop damage = approximately $198,000 (or greater depending on crop growth).

Using the NCDC database cumulative loss of $18.9 million in 52 years, average annualized windstorm losses to Dane County equal $363,462.


Development Trends

Increased construction of general property will proportionately increase the exposure to high winds, though modern building codes, better construction methods and materials may reduce the vulnerability. Powerlines and above-ground cables, pipelines, or networks remain vulnerable to the wind. Increased development could also threaten natural windbreak systems in place, increasing exposures of property and population. Conversely, increased development utilizing natural windbreak landscaping will reduce these exposures.


Based on the previous assessments, the overall risk rating for windstorms is high. Table 4.40 provides the summary of all aspects of the hazard profile that were evaluated to establish an overall hazard rating.

Table 4.40 Overall Risks for Windstorms








4.3 Vulnerability Summary Requirement §201.6(c)(2)(ii)(A): The plan should describe vulnerability in terms of the types and numbers of existing and future buildings, infrastructure, and critical facilities located in the identified hazard areas.

Requirement §201.6(c)(2)(ii)(B): [The plan should describe vulnerability in terms of an] estimate of the potential dollar losses to vulnerable structures identified in paragraph (c)(2)(i)9A) of this section and a description of the methodology used to prepare the estimate.

4.3.1 Methodology

Vulnerability is the measurement of exposed structures or populations relative to the risk of the hazard. For most hazards, vulnerability is a best-estimate. Some hazards, such as flood, affect specific areas so that exposure can be quantified, and vulnerability assessments result in a more specific approximation. Other hazards, such as tornados, are so random and unpredictable in location and duration that only approximate methods can be applied. This section provides a summary of the vulnerability assessments for the four major exposure categories profiled in each hazard: population, general property, essential infrastructure, and natural, historic and cultural resources. These assessments apply, generally, to all hazards, and the section is referenced frequently in the hazard profiles section. Where specific vulnerabilities arise for a specific hazard, those assessments are included only in the hazard profile. The numbers and assessments collected here, then, reflect the general vulnerability picture for the county, rather than specific circumstances.

4.3.2 Vulnerable Populations

A vulnerable population is any population which requires additional assistance, consideration, planning time, evacuation time, shelter needs, or communication methods during prior to, during, or after a disaster. Possible indicators of vulnerability may include age, disabilities, medical conditions, living arrangements, family size, poverty status, transportation limitations, language barriers, or communication availability.

Generally, the entire population experiences some level of vulnerability to natural hazards. This overall vulnerability is assumed in planning and mitigation efforts. However, there are specific aspects of a population that may be more vulnerable than others, and those are particularly important to consider in mitigation planning. This section examines six populations segments with a generally-increased vulnerability to hazards. Sometimes, an individual may fall into multiple risk categories simultaneously. For example, a child who is also disabled falls into two risk categories. Therefore it is important to remember that each of the six population segments examined below identifies the percent of vulnerable population relative to the total, and does not include any other categories of vulnerability. The demographics of Dane County’s population and their vulnerability to specific hazards are analyzed in more detail in the following section.

Age

Table 4.41 outlines the population for Dane County by age group. This table provides the foundations for extrapolating additional data regarding particular characteristics of the county’s population. Of particular interest are those under the age of 18 or over the age of


65. These age groups are traditionally considered more vulnerable to hazards than other age groups due to the characteristics associated with young or old age, such as mobility challenges, special dietary needs, supervision or assistance, full-time medical care, limited transportation availability, and other special considerations. The current estimated population with special considerations due to age is 164,398, or 35 percent of Dane County’s total population. In comparison, 36.7 percent of Wisconsin’s population falls into this category of vulnerability. Age is considered a primary exposure for the hazards of extreme heat, extreme cold, and hazards requiring a potentially rapid evacuation or movement towards a sheltered place, such as tornados.

Table 4.41 Population by Age Group in Dane County

Age Group (in Years) 2007 Estimate % of Population

Under 5 years 29,775 6.34%

5 to 9 years 28,554 6.08%

10 to 14 years 27,815 5.92%

15 to 19 years 34,327 7.31%

20 to 24 years 45,237 9.63%

25 to 34 years 71,494 15.22%

35 to 44 years 71,509 15.22%

45 to 54 years 69,204 14.73%

55 to 59 years 28,928 6.16%

60 to 64 years 18,690 3.98%

65 to 74 years 22,453 4.78%

75 to 84 years 15,678 3.34%

85 years and over 6,045 1.29%

Total Population 469,709 -

Median Age 34.7 -

Special Age Populations 164,647 35.05% Source: 2005-2007 American Community Survey 3-Year Estimates

Disabilities

Other population characteristics that reflect inherent vulnerability are those who live with disabilities. Table 4.42 shows the number of individuals who live with disability in Dane County, broken into several age statistics. Though all individuals living with disabilities are considered an at-risk population, the young and the old have a combined risk, as they experience both the exposures caused by the disability and the exposures associated with age. Overall, nearly 11 percent of Dane County’s population over the age of 5 lives with a disability of some kind. Although 2007 estimates for the state are not available, in 2000 there were 790,917 people above the age of five living with a disability in Wisconsin. This equates to approximately 14.1 percent of the population. People with disabilities are most vulnerable to hazards that may require unassisted evacuation or movement to a sheltering point, such as a tornado, or events where supplies and essential resources such as power and water may become limited or temporarily unavailable due to the hazard’s impacts, such as excessive heat, severe cold, severe winter storms, or drought.


Table 4.42 Disabled Populations in Dane County

Disability Status Estimates Number Percent

Total population from 5 to 15 years old 62,110

With a disability 3,883 6.3%

Total population from 16 to 64 years old 330,546


Total population over 65 years old 42,413


Total Selected Population 435,069

With a disability 47,403 10.9% Source: 2005-2007 American Community Survey 3-Year Estimates

Language Barriers

Language barriers of the population create additional dimensions of vulnerability in the population. Individuals who are not proficient in the English language may not receive important communications about hazards, response mechanisms, or warning systems. These individuals may also be hindered in the ability to find shelters, prepare for disasters, or file appropriate recovery forms and other paperwork. They may have difficulty communicating medical needs or other considerations to emergency responders. Table 4.43 indicates that approximately 11 percent of the Dane County population speaks a primary language other than English, and that about 1,800 people speak English less than “very well”. For comparison, on a statewide level, 7.3 percent of the population do not speak English in the home. This related statistic helps indicate the level of exposure to hazards. The population with language barriers are most vulnerable during hazards which have warning periods, such as tornados, floods, severe storms, hail, lightning, and windstorms. Language barriers may prevent the population from understanding the danger or from responding appropriately.

Table 4.43 Non-Proficient English Speaking Population in Dane County

Ethnicity and Language Spoken from the 2000 Census Number Percent

Population 5 years and older 43,9934 -

Language other than English 48,007 10.91%

Speak English less than “very well” 1,824 0.41% Source: 2005-2007 American Community Survey 3-Year Estimates

Living Arrangements

Living arrangements are often used to help mitigate the effects of age or disabilities, but may increase exposure to disaster. Individuals requiring special care may live in assisted living facilities or in nursing and long-term care facilities, which provide specialized care and assistance for daily life. These facilities may require additional time to prepare for, respond to and recover from disasters. Often, these populations cannot be accommodated in general shelters. Accurate potential exposure numbers are critical both to assessing potential impacts and risk assessments and in drafting emergency operations plans. Table 4.44 outlines the capacity or licensed bed number for the special populations care facilities in Dane County. These numbers represent the total potential exposure by license. At this


time, data from the Wisconsin Department of Health indicates that special population care facilities operate at or just below maximum capacity. The total exposed population value is 15,827, or 3.4 percent of Dane County’s overall population. These populations are most vulnerable to hazards that may impact the continuity of utilities and other vital services, such as tornados, excessive heat or cold, prolonged winter storms, hail and lightning damage, drought (indirectly), or windstorms. They are also vulnerable to hazards that may require evacuation, as these populations are inherently difficult to transport. Examples include wildfire and flooding.

Table 4.44 Special Populations Care Facilities and Hospitals in Dane County

Facility Type Number of Facilities Population

Total 203 15,827 Assisted Living Housing1 165 3,866 (capacity)

Adult Family Home 39 150 (capacity)

Community-Based Residential Facilities 99 2,054 (capacity)

Adult Day Care Programs 9 223 (capacity)

Residential Care Apartment Complexes 18 1,439 (capacity)

Long Term Care Facilities2 21 1,894 (beds)

Alzheimer Units2 6 198 (registered individuals)

Facilities for Developmental Disorders3 1 18 (beds)

State Mental Health4 1 1,403 (discharges)

Hospices5 1 -

Home Care Populations6 9 7,177 (registered individuals)

Hospitals7 5 1,399 (1,469 possible beds)

Select Specialty Hospital - 23 (beds)

University of Wisconsin Hospital and Clinics - 489 (beds)

Stoughton Hospital - 69 (beds)

Meriter Hospital - 448 (beds)

St. Mary’s Hospital - 370 (440 licensed beds) 1Source: Wisconsin Department of Health Services – Assisted Living Directories and Facility Profiles Website.

2Source: Wisconsin Department of Health Services “Nursing Homes and Residents 2005 Annual Report”

3Source: Wisconsin Department of Health Services “Facilities Serving People with Developmental Disabilities 2005 Annual Report”

4Source: Wisconsin Hospital Association Information Website – Health Care Data Report 2008

5Source: Wisconsin Department of Health Services “Hospices and Patients 2005 Annual Report”

6Wisconsin Department of Health Services “Home Health Agencies and Patients 2005 Annual Report”.

7 Source: Wisconsin Hospital Association Information Website – Health Care Data Report 2008

Family Groups

Family groups are also important factors of population exposure. Parents or other adults help care for children, and may mitigate the level of risk associated with the very young. Elderly populations who do not require nursing or other specialized care may also live with


younger populations, reducing their exposure to disasters. Conversely, some living situations may increase overall exposure, such as households where grandparents are caring for young children. In that case, the combination of two at-risk age groups in a single living environment without the mitigating effects of a non-risk age group may potentially increase the exposure of that household. Single parent households may also have increased exposures because the capability of the adult to care for the children may be compromised by working or housing arrangements. Knowing the general makeup of family groups, as well as the number of individuals living alone and living locations, is a major factor in evaluating the vulnerability of the Dane County population. According to Table 4.45, about 1.5 percent of all families in Dane are composed of grandparents raising grandchildren. These families make up the greatest exposure values within family groups. Another 18.4 percent of families are single-parent in nature, and are also considered to have a higher exposure value than two-parent family groups. Finally, approximately 12.5 percent of the population lives alone, and 22.3 percent of that population are above the age of 65. These population groups are vulnerable to hazards that do not have a long onset period, such as tornado or hailstorms, and to hazards that impact continuity of services or may threaten physical structures, such as flooding, excessive heat and cold, prolonged severe winter storms, and windstorms.

Table 4.45 Households by Type in Dane County

Number Percent

Number of all Families 109,709 -

With related children under 18 years old 52,968 48.28%

With related children under 5 years old unknown unknown

Number of Single Female Parent Families 13,746 12.53%



Number of Single Male Parent Families 6,388 5.82%



Grandparents Responsible for Own Grandchildren 1,591 1.5%

Number of Individuals Living Alone 58,617 -

65 years and older 13,057 22.27% Source: 2005-2007 American Community Survey 3-Year Estimates

Poverty Status

Poverty impacts the ability of the population to adequately prepare for disasters, and may impact the response capabilities of the population as well. Families and individuals below the poverty line may be unable to create 72-Hour Preparedness Kits, which impacts their ability to shelter in place during or after disasters. This population may not be able to seek shelter in alternative housing or hotels, or even to locate away from the disaster with advance warning, which increases the strain on local shelters and emergency rescue personnel. Income levels may affect the number of vehicles available to the population for evacuation requirements, and it may impact the availability of telephone communications, meaning that portions of the population may not receive important hazard updates via response mechanisms such as Reverse-911. According to Table 4.46, nearly 11 percent of


Dane County’s population lives below the poverty level and 4.6 percent of this population is composed of families. Overall, 40 percent of Dane County’s population receives some form of supplemental income. 6.3 percent of the population does not have access to a personal vehicle and another 4.3 percent does not have access to a land-line telephone. Statewide, 10.8 percent of the population lives below the poverty level. These populations are vulnerable to hazards that require public communication and warning, such as tornado, hailstorm, lightning, and flooding, because there may not be access to conventional warning mechanisms such as radio, television, and telephone. These populations are also particularly vulnerable to hazards that require evacuation, particularly for prolonged periods, as they may lack the financial resources to shelter for long periods of time or even to evacuate in the first place. These hazards may include flood, wildfire, or particularly severe winter storms or excessive heat and cold incidents that remove basic utilities for extensive periods of time.

Table 4.46 Families and Individuals below Poverty Level in Dane County

Demographic Number Percentage

All families 8,641 4.60%

With related children under 18 years 665 7.70%

Married couple families 130 1.50%

With related children under 18 years 199 2.30%

Families with female householder, no husband present 1,953 22.60%

With related children under 18 years 2,532 29.30%

All people 50,729 10.80%

Under 18 years 5,377 10.60%

Related children under 18 years 5,225 10.30%


18 to 64 years 5,834 11.50%


People in families 2,790 5.50%

Unrelated individuals 15 years and over 12,936 25.50%

Household Income Sources and Levels Number Percent

Number of Households with Social Security Income 36,084 19.21%

Mean Social Security Income (in dollars) $15,523 -

Number of Households with Supplemental Security Inc. 3,938 2.10%

Mean Supplemental Security Income (in dollars) $7,842 -

Number of Households with Retirement Income 26,983 14.36%

Mean Retirement Income (in dollars) $24,554 -

Number of Households with Public Assistance Income 1,768 0.94%

Mean Public Assistance Income (in dollars) $3,686 -

Number of Households receiving Food stamps (in last 12 months) 6,429 3.42%

Unemployed Individuals 11,909 2.54%

Other Social Economic Considerations Number Percent

No Vehicle 13,019 6.27%

No Telephone 9,080 4.37% Source: 2005-2007 American Community Survey 3-Year Estimates


4.3.3 General Property

Table 4.47 shows the property inventory from the Assessor’s Office (December, 2008) for the entire County. Only the value of the parcel improvements was analyzed for the purposes of this plan, and land value typically is not affected by a disaster. The totals shown below are summarized by general land use categories. These values are used to estimate exposure and potential losses to hazards such as flood, tornado, and dam failure. It also represents the sum total of property value exposed to severe weather hazards such as hail, windstorm, severe winter storm, and wildfire. Actual structural counts for the County are much higher, as one improved parcel may have multiple structures associated with it. In addition this table only captures values that have a property tax assessed on them. Certain government property, churches, and schools are exempt and not captured in this data. The majority of property value in Dane County is associated with residential improvements.

Table 4.47 Property Exposure Summary for Dane County

Property Type Total Parcel Count

Improved Parcel Count Improved Values ($) Content ($) Total Value ($)

Residential 123,301 118,540 23,135,641,917 11,567,820,959 34,703,462,876Agriculture 25,242 5,943 1,025,165,100 1,025,165,100 2,050,330,200Other 24,493 7,774 2,243,672,800 1,121,836,400 3,365,509,200Commercial Sales 2,968 2,516 1,767,646,859 1,767,646,859 3,535,293,718Commercial Services 2,501 2,112 2,665,224,002 2,665,224,002 5,330,448,004Transportation 1,851 404 93,204,200 46,602,100 139,806,300Industrial 1,802 1,177 1,039,728,600 1,559,592,900 2,599,321,500Institutional/Government 1,445 237 176,754,900 176,754,900 353,509,800Utilities 386 39 34,772,500 52,158,750 86,931,250Total 183,989 138,742 32,181,810,878 19,982,801,970 52,164,612,848

Source: Dane County Land Information Office’s Database, December 2008

The previous table was derived from the County’s GIS-based parcels layer, which included the assessed valuations as attributes. There was no way to identify property type based on this data alone. In order to identify the property type a GIS intersect was performed with the land use layer. Detailed land used codes were grouped into the property types shown in Table 4.45 to allow for summary by the property type. There are some limitations to this data, as there were several land use codes that did not match a land use identification key. These were included in the ‘Other’ grouping. Also, a parcel may have several land uses, such as agricultural and residential. The geographic center of the parcel was used to assign a single land use code. Another limitation is that the land use layer was created during a land use survey in 2005, and the assessor’s database was representative of late 2008. In some cases land once classified as vacant, or open woodland, had substantial improved values, indicating that this land has been developed, but the type of development is unknown. Vacant land is included in the ‘Other’ category, including land that was under construction.

Table 4.48 presents the housing demographics for Dane County. About 1 percent of all of Dane County’s housing units is manufactured housing, which are particularly vulnerable to hazards such as tornado, windstorms, hail, and flooding. These are also profiled in the following section as a vulnerable facility.


Table 4.48 Housing Demographics for Dane County

Housing Situation Number of Units Percent of all Units

Total Units 207,646 -

Occupied 187,852 90.47%

Occupied- Owner 119,043 57.33%

Occupied- Renter 68,809 33.14%

Vacant 19,794 9.53%

Single-Family Home (1 unit) 110,015 52.98%

Multiple-Family Homes (2 units) 15,417 7.42%

Apartments (3+ units) 79,822 38.44%

Campus Housing 21 .01%

Manufactured Homes 2,323 1.12%

RV/Boats/Vans/Other 69 0.03%Source: 2005-2007 American Community Survey 3-Year Estimates

4.3.4 Critical Facilities and Other Assets

Critical facilities are defined for this plan as physical structures that if damaged or destroyed compromise public health or safety, or are disproportionately vulnerable to natural disasters discussed in the plan, or house populations that are disproportionately vulnerable to natural disasters. These are grouped into the categories below:

• Essential Infrastructure (includes public and private utility facilities that are vital to maintaining or restoring normal services to hazard areas before, during, and after a hazard event: airports, roads, bridges, communications facilities and towers, correctional facilities, electrical generation/distribution facilities, media outlets, national guard, natural gas supply, public safety (911) communications centers, public safety facilities (police, fire, EMS), public works garages, town/village/city halls, wastewater facilities, water utilities.

• Vulnerable Facilities (includes special needs populations or facilities, historic or economic assets) : Childcare centers, community based residential facilities, community centers, campsites, healthcare facilities, hospitals, nursing homes, historic properties, manufactured homes, long term care facilities, schools, special needs housing.

• Hazardous Materials Facilities: Structures or facilities that produce, use, or store highly volatile, flammable, explosive, toxic, and/or water-reactive materials.

• Natural Assets: Natural resource assets may include wetlands, threatened and endangered species, or other environmentally sensitive areas. Natural resources can be important in mitigating hazards, such as wetland protection for reducing stormwater runoff and floodwater storage and infiltration.

The following is a general description of these assets. Dane County has an extensive inventory of these assets in GIS databases, which was used for exposure and vulnerability analysis purposes. Maps of the facilities can be referenced in Appendix G Critical Facilities Maps.

Essential Infrastructure

Airports. Dane County is home to four paved runway airports: Dane County Regional Airport (DCRA) north of the City of Madison, Morey Airport outside the City of Middleton,


Black Hawk Airfield in the Village of Cottage Grove, and Waunakee Airport in the Village of Waunakee. DCRA is the only airport that handles commercial airline traffic. Dane County GIS data indicates 37 airports, the majority of which are assumed to be private grass or dirt runway strips.

Communications Towers. The combined total of all towers based on County GIS data is 332; 132 are FCC towers and 200 are categorized as communications Towers. These are communication towers in the County owned by governments, individuals, cellular phone companies, hospitals, universities, and televisions stations. They are instrumental for public safety communications, cellular phone use, television, radio, paging, messaging, and other communications.

Correctional Facilities. According to County GIS data there are 5 Jails and 14 Correctional facilities in the County.

Electrical Generation/Distribution Facilities. Dane County’s electrical service is provided by numerous utilities and companies, which generate electricity, and own, maintain, and construct the distribution infrastructure.

• American Transmission Company owns, operates, monitors and maintains major transmission lines in the County and cooperates with local electric utilities in providing Dane County residents with electricity.

• Alliant Energy’s Corporation provides gas and electric services to communities in south-central Wisconsin, including parts of the Madison area—from Blue Mounds to Cambridge and from DeForest to Brooklyn.

• Madison Gas and Electric Co. (MG&E) provides electric service and natural gas for Madison, Monona, Fitchburg, Middleton, Cross Plains and other Dane County communities.

• Wisconsin Public Power, Inc. generates electricity and owns, operates, and improves electrical infrastructure for member utilities including Sun Prairie, Stoughton, Waunakee.

• The majority of power used by Dane County residents is produced outside the County. The Blount Generating Station, owned and operated by MG&E, is the only significant power plant in the County. Blount generally provides 10 to 15 percent of the electricity supplied to MG&E customers. Blount is powered by coal with a mix of natural gas and pre-consumer plastic and paper products.

Media Outlets. The Madison area broadcast stations are essential partners in the County’s plans to communicate with the public before, during, and after a disaster. There are five broadcast television stations, one cable television system, and four radio groups with a total of 22 stations, as well as numerous independent radio stations that serve the Dane County area. Media outlets are extremely important component of the public safety infrastructure.

National Guard. DCRA is adjacent to Truax Field which is home to the Air National Guard 115th Fighter Wing. This fighter wing operates two-dozen buildings on the airport grounds. The organization has a distinct economic impact on the Dane County area, generating an estimated $43 million in expenditures. The Army National Guard 147th Command Aviation Battalion is also located at Truax Field has 14 UH-60 Black Hawk helicopters.

Natural Gas Supply. MG&E, the largest supplier of natural gas in the County, purchases gas on the open market from more than 30 marketers and producers. Natural gas supplies are produced in Canada, the Texas and Oklahoma panhandle region, and the Gulf Coast of Louisiana. It is transported to MG&E’s distribution system through two pipelines companies: ANR Pipeline Co. and Northern Natural Gas Co. From there gas is supplied to area homes for


heating and cooking. There is no GIS-based natural gas facility layer, only transmission lines.

Public Safety Communications (911) Centers. The Dane County Public Safety Communications (911) Department provides countywide 911 emergency call-taking services. The County 911 Center provides dispatching and centralized communications services for the Dane County Sheriff’s Department as well as 21 local law enforcement agencies. The 911 Center also provides communications and dispatching services to 22 local fire departments and 21 local EMS agencies.

• In addition to the Dane County communications center, the cities of Middleton, Monona, and Sun Prairie each own and operate their own local public safety answering point (PSAP). The local units of government are responsible for maintenance and operation of these facilities.

• Two municipalities, the cities of Fitchburg and Stoughton, own and operate local dispatch centers, but do not receive 911 calls.

• Two state agencies in the County, the University of Wisconsin Police and Security and the Capitol Police operate call-taking and dispatch centers for facilities under their jurisdiction.

Public Safety Facilities. There are 20 local law enforcement agencies within the County. The unincorporated areas of the County and several villages rely on the Dane County Sheriff’s Office for law enforcement services. According to County databases there are 45 police stations, 5 precincts and there are 3 Sherriff Precinct Stations.

• Dane County has a cooperative program for Emergency Medical Services (EMS) to facilitate a uniform system of emergency medical care. The Dane County EMS regional system is composed of 22 local ambulance districts, which are formed by towns, villages, and cities.

• There are 38 fire stations in 28 fire districts in Dane County. However, 32 fire districts serve the County, as some districts cross the County jurisdictional border.

Public Works and Highway Garages. Public works buildings and highway garages contain staff and equipment critical to effective response to natural hazards. From County employees to snow removal equipment, these resources are instrumental in maintaining the functioning of government, businesses and everyday life after a natural disaster hits.

Town/Village/City Halls. Every unit of government in the County has a primary government building. This building is generally the town, village or city hall. There are 61 in all. These structures range from modified garages, to old school houses, to modern public buildings with the full range of amenities. These buildings serve as meeting and gathering spaces, locations for government staff, and as repositories for information and public records critical to the functioning of governments and communities.

Wastewater Facilities. The Madison Metropolitan Sewerage District serves approximately 300,000 people in the Madison area. Wastewater treatment for the entire district is performed at the Nine Springs Wastewater Treatment Plant. The District and it’s customers operate and maintain a combined total of 17 pumping stations and 169 lift stations lift stations in 5 cities, 7 villages, and 28 town sanitary/utility districts.

• In addition to MMSD, there are 17 municipal wastewater treatment facilities in the County. The wastewater collection and conveyance systems are operated and maintained locally.


• As of 1990, there were approximately 18,700 on-site wastewater disposal systems in Dane County, nearly all of which are were systems serving private rural residences. This number is expected to increase to near 28,000 by 2020.

Water Utilities. Groundwater supplies almost all of the water in Dane County for household, commercial, and industrial uses. Public water supplies make up more than 75 percent of the total water usage in the County. There are 26 municipal water utilities operating more than 85 groundwater wells and pumping stations across the County.

• In rural settings, over 21,000 private wells serve over 55,000 residents and agricultural operations in the County. The County GIS databases have 78 water utilities features and 126 wells.

Vulnerable Facilities

Campsites. Dane County contains approximately 258 overnight individual camping sites at 7 locations: Babcock, Brigham, Indian Lake, Lake Farm, Token Creek, Mendota, and Kegonsa Parks. Dane County Land & Water Resources Department - Parks Divisionmanages all these sites with the exception of Kegonsa Park, which is a state park managed by the Wisconsin Department of Natural Resources.

• Babcock Park has 25 campsites; Brigham has 26, Indian Lake 1, Lake Farm 54, Token Creek 39, Mendota 30, and Kegonsa 83.

Childcare Centers. Childcare centers as vulnerable facilities are those where there are eight or more children on site at any one time. These facilities, because of the relatively high child-to-adult ratio and length of time children spend at the facilities, are particularly vulnerable to the impacts of natural hazards. There are 564 day care centers serving 19,482 children in Dane County.

Community Based Residential Facilities (CBRF). The term CBRF covers a wide range of facilities assisting people with a wide range of needs. They may house and assist people who are elderly, mentally ill, physically disabled, alcoholic or drug dependent, emotionally disturbed, have criminal records, or are infants. People within these facilities often have moderate to great difficulty in taking care of themselves. They may be entirely dependent upon aid workers in an emergency. CBRFs can be managed or owned by private corporations specializing in assisting special need populations, churches, non-profit organizations, or hospitals. There are 91 CBRFs in Dane County.

Community Centers. Because community centers are gathering points for neighborhoods and offer social services, they are an indispensable element to the functioning of communities and are an embodiment of social capital of neighborhoods. There are 25 community centers in the County.

Healthcare Facilities. Dane County has five major hospitals, Meriter Hospital, St. Mary’s Hospital Medical Center, University of Wisconsin Hospital and Clinics, William S. Middleton Veterans Administration (V.A.) Hospital and Stoughton Hospital and Clinics. There are also more than 50 clinics and urgent care centers in the County.

Historic Properties. According to the Wisconsin Historical Society there are 136 individual historical properties, as well as numerous buildings in the 23 historic districts are present in the County. The County also contains historic parks, Native American effigy mound sites, and archeological districts. The County GIS layer includes 235 historic sites.


• Historic properties and landscapes play a significant role in the region’s communities. Buildings offer character and points of interest that cannot be replicated. They enhance the sense of place that makes a local unique and meaningful. Having symbols of the past deepen people’s understanding of the place, time and culture in which they are living. This creates an identity for neighborhoods, downtowns, and rural areas that enhance the quality of life.

Manufactured Homes. Once called mobile homes, the appropriate term is now manufactured homes, because less than five percent of the homes are actually moved from their initial place of occupancy. There are approximately 2,049 manufactured home units in Dane County in the year 2000. Most of these are sited in one of the fourteen “mobile home parks” located in Dane County. Manufactured homes are also located on individual parcels of land in rural areas of the County.

Long-term Care Facilities. Commonly referred to as nursing homes, long-term care facilities house people who, because of health reasons are not able to live at home and care for themselves. Over 1,862 people are served by approximately 21 nursing homes in the County. People within these facilities often have great difficulty in taking care of themselves. They may be entirely dependent upon aid workers in an emergency.

Schools. There are 146 schools in Dane County, including 128 public and 18 private. There are nearly 70,000 students enrolled in the elementary, middle, and high schools of the County.

Special Needs Housing. Special needs housing consists of about 49 apartment building facilities in the County serving about 6,500 people. The populations within these structures have limited capacities to function in everyday life and need assistance from care providers. This housing offers support services for the elderly, homeless, disabled, handicapped, or other residents with special needs. Support services may include case management, medical or psychological counseling and supervision, cleaning, childcare, transportation, and job training.

4.3.5 Hazardous Materials Facilities

Extremely Hazardous Substances. Facilities that use U.S.E.P.A. listed Extremely Hazardous Substances are required by state and federal regulation to work with local authorities and emergency response agencies to develop an Off-site Emergency Response Plan for their facility. The list of extremely hazardous substances contains more than 300 chemicals. Because of their extremely toxic properties and widespread industrial use, these chemicals were chosen to provide a focus for chemical emergency planning. If these chemicals are released in high enough quantity, they can be of immediate concern to the surrounding community.

• There are 149 facilities in Dane County on record as having developed off-site response plans as required by the state and federal regulations.

Hazardous Chemicals. State and federal regulation also require facilities that have or use large quantities of hazardous chemicals to annually report inventory and storage information to local authorities and emergency responders. The presence of any hazardous chemical onsite in quantity of 10,000 pounds or more must be reported. As of 2008 There are currently 323 facilities in Dane County that meet this requirement.


Table 4.49 is a summary of the critical facilities in Dane County, updated to reflect GIS data inventories as of March 2009. Included in this table is the sum of the number and replacement value (where available) of these facilities exposed to hazards such as lightning, hail, windstorm, tornado, excessive heat, and severe cold. New to the plan during 2009 was an analysis of vulnerability to flooding. The table represents the total count of structures located in either the DFIRM 100 or 500 year flood zones, and/or the 100-year flood hazard area as modeled by HAZUS-MH (see flood profile for further information). The inventory of facilities is provided in more detail in the jurisdictional annexes, including more information on specific facilities at risk to flooding. Countywide maps of these facilities can be referenced in Appendix G. The locations of these facilities are also located on maps for each jurisdiction in the jurisdictional annexes.

Table 4.49 Critical Facility Summary

Facility Type No. of Facilities

Replacement Value ($)

Total Potentially flood-prone

DFIRM 100-Yr

DFIRM 500-Yr

HAZUS Only

Essential Facilities

Airport* 37 599,400,000 4 1 1 2

Bridge 87 87,000,000 47 36 11

Communications Tower 200 152,403,800 15 11 2 2

Correctional Center 14 17,969,600

Electric Substation 72 1,855,600 9 3 2 4

Emergency Shelter 8 119,600

EMS Station 33 2,237,000 1 1

FCC Tower 132 126,312,200 12 10 1 1

Fire Station 38 513,500 3 2 1

Food Pantry 46 5,426,100

Hospital 5 unknown

Jail 3 unknown

Media Outlet 22 26,567,200

Municipal Hall 60 687,200 6 3 1 2

National Guard 1 unknown 1 1

Police 30 unknown

Powerplant* 5 2,500,000,000 1 1

Sheriff Precinct 4 unknown

Wastewater Treatment* 13 2,600,000,000 5 3 0 2

Water Utility 78 898,900 1 1

Well* 126 50,400,000 4 3 1

Vulnerable Facilities

Adult Day Care 8 3,369,900 1 1


Facility Type No. of Facilities

Replacement Value ($)

Total Potentially flood-prone

DFIRM 100-Yr

DFIRM 500-Yr

HAZUS Only

Adult Family Home 37 6,076,803

Affordable Rental Housing 34 unknown 2 1 1

Campus Housing 21 unknown

Child Care 564 127,158,924 4 2 1 1

Community Based Residential 6 409,000 2 2

Community Center 91 82,416,600

Clinic 25 7,624,500

Federally Assisted Rental 67 24,380,000

Historic Site 235 110,798,700 8 5 2 1

Manufactured Home 2,049 unknown 246 173 19 54

Nursing Home 21 38,340,000 1 1

Private School 18 unknown

Public School 128 unknown

Residential Care Apartment Complex 15 22,439,500

Senior Center 16 14,799,000 2 1 1

Serving People w/ Disabilities 2 135,700

Single Room Occupancy 28 5,656,900

Subsidized Housing 51 17,753,800

Supportive Permanent Housing 16 214,700

Transitional Housing 21 2,070,700

Hazardous Material Facilities

Extremely Hazardous Substances 149 331,455,400 4 1 1 2

Hazardous Chemicals 323 576,340,000 22 4 6 12

TOTAL 4,939 7,543,230,827 401 259 42 100 Source: Dane County GIS databases; * Replacement value estimated based on default values associated with FEMA’s HAZUS documentation. All other replacement values based on assessed value, where available.

4.3.6 Vulnerable Natural, Historic and Cultural Resources

Natural, historic and cultural resources are important components of a community. Often, these resources serve as gathering points, tourist attractions, community pride centers, and important landmarks. Historic properties may be particularly vulnerable to hazards due to dated construction materials and practices, and often are considered irreplaceable aspects of the community. Historic properties also require special considerations when retrofitting for hazards such as flood and wind. Cultural resources may include community centers, concert or sporting venues, museums, galleries, lecture centers, libraries, and recreation centers. These facilities may be more vulnerable due to construction or due to contents - for example, a flooded library may be devastating in terms of cost and cultural loss.


Resource protection in Dane County recognizes that land and natural resources perform critical environmental functions such as groundwater recharge and discharge, water quality improvement, erosion control, storage of floodwaters, wildlife habitat, and scenic beauty. Some lands are particularly vulnerable in urban and developing areas. Natural resources are important to include in benefit-cost analyses for future projects and may be used to leverage additional funding for projects that also contribute to community goals for protecting sensitive natural resources. Awareness of natural assets can lead to opportunities for meeting multiple objectives. For instance, protecting wetlands areas protects sensitive habitat as well as attenuates and stores floodwaters.

The approach to resource protection in Dane County is based primarily on a countywide system of continuous open space corridors. Most lands in need of protection are associated with stream valleys and other water features. The corridors also emphasize the importance of continuity of environmental systems and protection of the land/water edge. Local governments, the Capital Area Regional Planning Commission, and state and federal agencies use the corridors to make decisions on the location of urban development and major facilities. The corridors are also used as the basis for open space and recreation planning and acquisition.

The primary functions of open space lands can be classified into five general categories. These include: (1) protection of public health, safety and property, including floodplains and steep slopes; (2) protection of natural resources and critical environmental processes, which includes wetlands and marshes, groundwater recharge areas, etc.; (3) satisfaction of community outdoor recreation needs, including parks, trails, nature study areas; (4) enhancement of scenic beauty and provision of buffer areas and separation between communities or incompatible land uses; and (5) resource production such as agriculture, forestry, and mining.

The protection of public health, safety and property is an extremely important function of open space corridors, with significant economic implications, such as avoiding or preventing development in areas subject to flooding. Open space corridors include a variety of environmentally sensitive lands and resource features including: lakes, ponds and streams; wetlands; floodplains; shoreland buffer strips along streams, drainageways, and wetlands. Table 4.46 includes natural (campgrounds), historic properties, and cultural resources (community centers). Maps of Dane County’s open space corridors are available online. Maps of planned land use in the local annexes include more detail on areas expected to remain designated as natural areas, parks/outdoor recreation, or woodland overlayed with flood hazard areas.

4.3.7 Risk Analysis Overview and Methodology

Overall, Dane County is at risk to thirteen different hazard categories. Each hazard was profiled and, based on the information in the profile, rated for the relative geographic extent, probability of future occurrences, magnitude and severity, and overall vulnerability for the county as a whole. The hazard mitigation plan update in 2009 employed a slightly different assessment methodology than was utilized in the initial 2004 plan. In the first plan, hazards were identified based on the contents of the Dane County Hazard and Vulnerability Analysis appendix in the County’s Emergency Operations Plan (EOP) and on input offered from the Citizens Advisory Committee. The hazards were then profiled individually and, finally, the hazards were ranked to reflect the overall vulnerability of the


County to each hazard, and to allow for a quantitative comparison between hazards.51 In the update, this table served as the basis for the initial hazard identification process reflected in Section 4.1 Hazard Identification. The hazards were profiled individually again with updated risk assessment methods and included recent occurrence data. Table 4.50 depicts the risk assessment criteria and the corresponding ratings and numeric values used in the hazard profiles, as identified in Section 4.2 Hazard Profiles. This information was collected and displayed at the end of each hazard profile, and also compiled in Table 4.51. This table allows for an easy comparison between the hazards profiled in this plan, provides for accuracy and consistency in the rating system, and assists with prioritizing the mitigation strategies for the hazards.

Table 4.50 Risk Assessment Criteria Ratings and Associated Values

Criteria Rating Value Rating Value Rating Value Rating Value

Geographic Extent Isolated 1 Limited 2 Significant 3 Extensive 4


Unlikely 1 Occasional 2 Likely 3 Highly Likely 4


Low 1 Medium 2 High 3

Impact Magnitude and Severity

Minor 1 Moderate 2 Critical 3 Catastrophic 4

Overall Risk Rating Low 1.9 or less

Medium 2.0-2.9 High 3.0 or higher

The corresponding interpretations of the numeric overall risk ratings established in the fourth column of Table 4.51 are drawn from the original planning methodology. This uses a standard interpretation where values from 0-1.9 reflect a low risk rating, 2.0 to 2.9 reflect a medium risk rating, and values of 3.0 or higher are associated with a high risk rating. This interpretation methodology was selected to provide continuity from the original plan into the update, and to show the progression of risk assessment from the initial hazard identification through the entire hazard profile process.

The original hazard ranking table and the new hazard rating table reflect similar information, using different graphic layouts. Both tables examine the hazards in terms of geographic extent, magnitude/severity, probability of future occurrence, and overall vulnerability. The major differences lie in how this information is presented. In the initial planning effort, the concept of geographic extent reflected common-sense indications combined with historical effort. This plan builds on that methodology and applies a standard terminology to allow for better comparison of extent between hazards. The initial planning effort also examined the probability of the event occurring in the future, based on the past records but no consistent mathematical formula was applied to all hazards. The updated plan reflects this methodology for all hazard profiles. The first planning effort examined vulnerability in terms of direct impacts on structures, facilities, and populations and in terms of indirect impacts on social and economic aspects of the County and in the potential for secondary hazards caused by the primary hazard. In the update, these ratings were profiled in each hazard and then averaged into a single vulnerability rating, which presented a cleaner and more uniform dataset.

51Dane County Department of Emergency Management, Dane County Natural Hazard Mitigation Plan 2004, p 53.


Of the thirteen hazards, five are considered to pose a higher risk to Dane County than the other hazards profiled. These hazards are: flooding, severe cold, severe winter storms, tornados and windstorms. Five hazards are classified as a medium comparative risk to the County. These hazards usually present one numerically significant rating while the other three criteria fall in a medium range. These hazards are: drought, fog, hailstorms, excessive heat, and lightning. Finally, three hazards are classified with a low comparative risk to Dane County. These hazards are profiled because one of the four evaluation criteria results in a high numeric value, while the other three criteria remain low. These hazards have minimal corresponding data, which indicates that for some reason, including the possibilities of luck and circumstance, these hazards have not had a significant impact within the County, though the potential exists. These hazards are: dam failure, landslides/sinkholes/erosion, and wildfire. While much of this plan’s mitigation objectives (or actions) will focus on the high risk hazards, mitigation opportunities may exist to prevent the low and medium risk hazards from becoming more significant.


Table 4.51 Summary of Risk Ratings for Hazards in Dane County

Hazard Geographic Extent

Probability of Future Occurrence

Impact Magnitude /Severity


Overall Risk Rating

Significant Unlikely Moderate Low Low Dam Failure 3 1 2 1 1.75

Extensive Likely Significant Medium Medium Drought

4 2 3 2 2.75

Significant Highly Likely Critical High High Flooding

3 4 3 3 3.25

Extensive Highly Likely Moderate Low Medium Fog

4 4 2 1 2.75

Significant Highly Likely Moderate Medium Medium Hailstorm

3 4 2 2 2.75

Significant Low Minor Low Low Landslides, Sinkholes and

Erosion 3 1 1 1 1.50

Isolated Highly Likely Moderate Medium Medium Lightning

1 4 2 2 2.25

Extensive Highly Likely Moderate Medium High Severe Cold

4 4 2 2 3.00

Extensive Likely Low Medium Medium Excessive heat

4 3 1 2 2.5

Extensive Highly Likely Critical Medium High Severe Winter Storm 4 4 3 2 3.25

Significant Likely Catastrophic Medium High Tornado

3 3 4 3 3.25

Limited Likely Minor Low Low Wildfire

2 3 1 1 1.75

Extensive Highly Likely Moderate Medium High Windstorms

4 4 2 2 3.00

4.3.8 Summary of Trends and Key Issues

The following is a summary of key issues from the Dane County risk assessment process.

Hazard Risk Comparison

• Subjective hazard ranking in 2004 improved with more detailed methodology that incorporated an averaged vulnerability rating, based on quantifiable numbers where possible.

• During the time frames between the 2004 plan and the 2009 update, Dane County has been impacted by 5 natural hazard events that lead to disaster declarations. In 2005, the State Disaster Fund responded to the Stoughton Tornado. In 2006 and 2007,


flooding resulted in Presidential Disaster Declarations, and in 2008 the County received a Presidential Emergency Declaration for snow and a Presidential Disaster Declaration for Severe Storms, Tornados, and Flooding.

• Based on available historic records the most costly hazards to the county in terms of property losses are Flooding ($385 million reported to NCDC between 1996 and 2008), Winter Storms ($135 million reported) and Tornados ($70 million between 1955 and 2008 reported to NCDC).

• Based on available historic records, the hazards resulting in the most direct or indirect human deaths and injuries are: Lightning, Tornado, Excessive heat and Severe Cold, and Flooding.

• In 2004, Tornado was, by a significant margin, ranked as the hazard of highest overall concern. In the 2009 update, Tornado was joined by Flooding and Severe Winter Storms as the hazards of highest overall concerns.

• Floods and Tornados have the greatest potential to damage structures and critical facilities.

• Tornados have the greatest potential to cause long-term social impacts on the community. Flooding was also ranked highly.

• Drought, Severe Winter Storms, Flooding, and Tornados have the greatest potential for long-term economic impacts on the community.

Dam Failure

• Analyzed during the 2009 update, there is some potential for dam failure impacts in Dane County, though the probability is low.

• Several dams have an ‘unknown’ hazard class; additional study is needed to classify the risk rating and potential downstream impacts

Drought

• Severe agricultural losses can occur during extended droughts. • There is a general lack of awareness of the potential impacts of a sustained severe

drought. • Drought often leads to an increased fire risk. • The lack of comprehensive water management policies can lead to a wide range of

secondary impacts. • There is a general lack of awareness of the potential far-ranging impacts of a sustained

severe drought. • There are great difficulties in predicting at what point a dry spell will become a drought.

As a result, the response, if any, is ad hoc and can be disorganized.

Flooding

• Significant floods occurred in both 2007 and 2008, causing approximately $40 million in damages as documented by the Department of Emergency Management.

• Residential flooding and corresponding losses in the entire Yahara River Basin has been a significant problem in the past. The damage potential for a 100-year flood indicates that the highest monetary loses in the County would be experienced along the Yahara River and Chain of Lakes.

• Residential flooding and corresponding losses in the Black Earth Creek Watershed has also been a significant problem in the past. The damage potential analysis indicates that Black Earth Creek Watershed has more buildings located within the mapped floodplain than any other watershed in the County. While the potential monetary losses are not as


high as those in the Yahara River Basin, a 100-year flood in the Black Earth Creek Watershed is likely to impact a greater number of people than a similar event in any other individual watershed.

• Agricultural flooding and corresponding crop loss in the Upper Koshkonong Creek Watershed.

• Residential flooding in the Roxbury Creek Watershed. Areas at risk of future flood losses include the hamlet of Roxbury, Fish Lake, and the floodplain of the Wisconsin River.

• High ground water table flooding is a primary flood problem, in addition to floodplain flooding; often these areas are not in mapped floodplains.

• Several communities have significant flood issues. These include: Town of Roxbury, Village of Oregon, Town of Madison, City of Monona, Village of Mazomanie, Village of Black Earth, among others.

• The use of recent digital flood hazard data (DFIRM and HAZUS) in the update has resulted in a higher degree of flood risk than was previously known.

• Several critical facilities have been identified in the floodplain during the 2009 update that were not previously known to be at risk.

Fog

• Increased numbers of fatal accidents occur when fog is a contributing factor.

Hailstorm

• Automobiles are particularly vulnerable to damage. • Crops are particularly vulnerable to damage at certain times in the growing season. • Commonly used roofing and siding materials are not resistant to hail impact, resulting in

the potential for widespread damage due to large hail.

Lightning

• Lightning strikes and resulting electrical surges can damage household electronics. • Lightning strikes and resulting electrical surges can damage the electrical distribution

system and cause power outages. • Lightning striking buildings can cause structure fires. • All of Dane County is at risk from lightning and personal protection is paramount for

lightning safety. Many people incur injuries or are killed due to misinformation and inappropriate behavior during thunderstorms.

Tornado

• Tornados continue to impact the County, with damage suffered from a series of tornados ranging in size from F0 to F3 on August 18, 2005, an F0 in 2006, and two F0 and two F1 events in 2008.

• The 2005 tornado, commonly called the Stoughton Tornado, is the current Tornado Event of Record, totaling $36.89 million in damages for Dane County alone.

• The storm shelters in County parks do not provide sufficient shelter to protect people from tornadoes.

• People seem to be unaware of available warning options besides sirens and broadcast media.

• See multi-hazard category.


Severe Cold

• Water pipes in homes are susceptible to freezing in prolonged extreme cold. • Water mains are susceptible to freezing. • People who are homeless are particularly vulnerable. • All age demographics are potentially vulnerable.

Excessive heat

• The National Weather Service rates extreme heat as the number-one weather related killer, nationwide and in the state of Wisconsin.

• The elderly, those in poor health, and those without air conditioning are particularly vulnerable.

• The increased electrical demand for air conditioning has the potential to overload distribution system and lead to outages.

Severe Winter Storms

• Severe winter storms have the potential to halt all transportation – countywide. • Motorists and travelers can become stranded on the highways of the County. • Winter storm events can pose a serious threat to the residents of Dane County. Many

fatalities during winter storms are the unsuspecting dangers that include heart attacks while shoveling snow and improper use of space heaters.

• Severe winter storm fronts can completely shut down businesses and government, while isolating residents in their homes for days and sometimes weeks.

Wildfire

• Intentional brush fires occasionally get out of control and produce small wildfires.

Windstorms

• Wind damage is a primary cause of loss or destruction of private property. • High winds and flying debris have the potential to cause personal injury and loss of life.

People who are outside, particularly in parks, campgrounds, golf courses, or large outdoor gatherings are particularly vulnerable.

Multi-Hazards

• Overhead power and telephone lines are vulnerable to damage by ice and wind. • Homes are often damaged due to falling tree limbs in wind and ice storms. • Tree damage leads to many secondary losses, such as road blockage, downed power

lines, and hindered emergency response. • Manufactured homes are especially vulnerable to many of the hazards, but particularly

high winds and tornadoes. Most manufactured homes do not have safe rooms. Most mobile home parks do not have storm shelters.

• Agricultural operations and critical facilities are particularly vulnerable to extended loss of electric power.

• Loss of electrical power is, in many cases, the cause of significant secondary consequences of a hazard event. Overhead electrical lines are particularly vulnerable to many of the natural hazards in Dane County.


• Individuals in a home-health care situation are particularly vulnerable to loss of electrical power.

• Manufactured homes, buildings with wide span roofs such as shopping malls or school gymnasiums are also particularly vulnerable to high winds.

• Falling trees and branches cause damage to power lines, block streets, damage buildings, inhibit emergency access, and is a major contributor to storm debris problems.

Section 4.4. Capability Assessment Thus far, the planning process has identified the natural hazards posing a threat to Dane County and described the vulnerability of the County to these risks. The next step is to assess what loss prevention mechanisms are already in place. This part of the planning process is the mitigation capability assessment. Combining the risk assessment with the mitigation capability assessment results in “net vulnerability” to disasters and more accurately focuses the goals, objectives, and proposed actions of this plan.

The HMPC used a two-step approach to conduct this assessment. First, an inventory of common mitigation activities was made through the use of a matrix. The purpose of this effort was to identify policies and programs that were either in place or could be undertaken, if appropriate. Second, the HMPC conducted an inventory and review of existing policies, regulations, plans, projects, and programs to determine if they contribute to reducing hazard related losses. Each participating entity completed this assessment through a data collection guide provided during the 2009 update planning process. The County’s assessment is presented here. The jurisdictional annexes capture the capability assessment respective to each jurisdiction.

4.4.1 Mitigation Capabilities Summary

Table 4.52 lists planning, regulatory, and land management tools typically used by local governments to implement hazard mitigation activities and indicates those that are in place in Dane County. The table below was filled out during the planning process by a team of Dane County employees from various departments. The tables are followed by narratives that describe some of these capabilities in more detail.

Table 4.52 Dane County Regulatory Mitigation Capabilities

Regulatory Tool (ordinances, codes, plans)

Yes/ No Comments

General or Comprehensive plan

Yes Chapter 82 – Dane County Comprehensive Plan http://www.daneplan.org/plan.shtml

Zoning ordinance Yes Chapter 10 – Zoning Ordinance http://www.countyofdane.com/unified/information/ordinances.aspx

Subdivision ordinance Yes Chapter 75 – Land Division and Subdivision Ordinances http://www.countyofdane.com/unified/information/ordinances.aspx

Urban Sewer Service Area Approvals

Yes Available from Capital Area Regional Planning Commission.

Floodplain ordinance Yes Chapter 17 – Floodplain Ordinance http://www.countyofdane.com/unified/information/ordinances.aspx


Regulatory Tool (ordinances, codes, plans)

Yes/ No Comments

Other special purpose ordinance (stormwater, steep slope, wildfire)

Yes Chapter 11 – Shoreland, Shoreland-Wetland, and Inland-Wetland Regulations Townships have burning ordinances for open burn

Building code Yes The county follows the State building code which follows the Universal Building Code (UBC)

Fire department ISO rating

NA County does not have its own fire department. Would be applicable on a jurisdiction basis

Erosion or sediment control program

Yes Chapter 14 – Stormwater and Erosion Control Plan http://www.countyofdane.com/unified/information/ordinances.aspx

Stormwater management program

Yes Chapter 14 – Stormwater and Erosion Control Plan http://www.countyofdane.com/unified/information/ordinances.aspx

Site plan review requirements

No Nothing formal. Incorporated in zoning and various ordinances such as stormwater and erosion control. Chapter 10 and 14.

Capital improvements plan

Yes

Economic development plan

No Chapter 82, Incorporated in Comprehensive Plan

Local emergency operations plan

Yes Public Health Emergency Plan – Available Hardcopy Dane County EOP with Emergency Support Functions – Hardcopy only

Other special plans Madison Metropolitan Planning – TIP – Online Public Health Emergency Plan (PHEP) – Hardcopy only Parks and Open Space Plan – Mitigation for recreational stream use and campsites. Identify areas where county is looking to purchase to alleviate flooding and protection of natural resources. (online) Consolidated Plan – Meeting HUD requirements to get grants (needs assessment for population and housing needs) Community Block Grants – Can use funding for flooding issues if property in floodplain and meets low income requirements Land and Water Management Resource Plan – Component that deals with stream bank restoration. Also deals with erosion and water issues (online) (human services website) Action Plans for Dams (Stewart Lake, Babcock, Tenet lock and dam) – Have dam breach analysis for Stewart Lake and working on Tenet Lock and Dam Mass Clinic Plans (Public Health) for various sites for Dane County and City of Madison - more for public health than hazards. Emergency Action Plan for Prairie Du Sac – Not in Dane County but part of the same floodplain. Available hardcopy

Flood insurance study or other engineering study for streams

Yes Recent update to flood plain maps Flood Insurance available online (Planning Development website) http://www.countyofdane.com/plandev/zoning/ Streams (combination of Parks and Open Space Plan and Land and Water Resources Plan)

Elevation certificates (for floodplain development)

No Zoning Division At least on paper only for construction in floodplain

Other Dane County Drainage Board (covers all jurisdictions) Security Plans

Table 4.53 identifies the personnel responsible for mitigation and loss prevention activities as well as related data and systems in Dane County.


Table 4.53 Responsible Personnel and Departments for Dane County

Personnel Resources Yes/No Department/Position Comments

Planner/engineer with knowledge of land development/land management practices

Yes Land and Water Resources Department

Land Management (8)

Engineer/professional trained in construction practices related to buildings and/or infrastructure

Yes Land and Water Resources Department of Public Works Dane County Rodefeld Landfill

Construction (4) Engineers (7) Technician (1) Technician (1)

Planner/engineer/scientist with an understanding of natural hazards

Yes Land and Water Resources

8 positions

Personnel skilled in GIS Yes Land and Water Resources Land Information Office Planning and Development Capital Area Regional Planning Commision

2 positions 2 positions 1.5 positions .5 positions

Full time building official Yes

Floodplain manager Yes Planning and Development 1 position

Emergency manager Yes Dane County Emergency Management

Grant writer Yes Land and Water Resources 3 positions

Other personnel

GIS Data Resources (Hazard areas, critical facilities, land use, building footprints, etc.)

Yes Land and Water Resources Dane County Emergency Management

2 positions

Warning Systems/Services (Reverse 911, EAS, outdoor warning signals)

Yes Dane County Emergency Management Dane County Public Safety Communications

1 position 1 postion

Other

Table 4.54 identifies financial tools or resources that Dane County could potentially use to help fund mitigation activities.

Table 4.54 Financial Resources for Dane County

Financial Resources Accessible/Eligible to Use (Yes/No) Comments

Community Development Block Grants Yes Dane County applies for directly/Human Services

Capital improvements project funding Yes Department of Administration – Bonded (borrowed money) – Apply (Department of Administration Website)

Authority to levy taxes for specific purposes

Yes Drainage Board has special Assessment Authority annual meeting to let people know County Board

Fees for water, stormwater, sewer, gas, or electric services

No Not under County

Impact fees for new development Yes Accessible but not currently used


Financial Resources Accessible/Eligible to Use (Yes/No) Comments

Incur debt through general obligation bonds

Yes County Board Approval – legislative

Incur debt through special tax bonds No

Incur debt through private activities No

Withhold spending in hazard prone areas

No

4.4.2 Additional Capabilities

Existing County Hazard Management Programs

The National Flood Insurance Program and Floodplain Zoning

The NFIP is a voluntary federal program enabling property owners in participating communities to purchase insurance as a protection against flood losses with the stipulation that the state and local community have in place floodplain management regulations that reduce future flood damages. These regulations must meet standards contained in Section 60.3 of the NFIP regulations. Participation in the NFIP is based on an agreement between communities and the federal government. If a community adopts and enforces a floodplain management ordinance to reduce future flood risk to new construction in floodplains, the federal government will make flood insurance available to renters, homeowners, and businesses within the community as a financial protection against flood losses. This insurance is designed to provide an insurance alternative to escalating federal disaster assistance costs.

All cities, villages, and counties in Wisconsin with a mapped flood hazard are required to adopt reasonable and effective floodplain zoning ordinances. Chapter 87 of the Wisconsin statutes and NR 116 of the Wisconsin Administrative Code define floodplain zoning authorities and requirements. Dane County has been eligible for flood insurance on private and commercial properties under the Flood Disaster Protection Act of 1973 since the fall of 1975.

The regulatory definition of a floodplain is the area of land adjacent to a river or body of water, which has been or may be covered by water during a 1 percent probability (100-year) flood event. The floodplain includes the floodway and the floodfringe, and may include other designations. The floodway is the channel of a river or stream and those portions of the floodplain adjoining the channel required to carry the 1 percent probability flood discharge. The floodfringe is the portion of the floodplain outside of the floodway, which is covered by floodwaters during a 1 percent flood and is generally associated with standing water rather than flowing water.

Chapter 17 of the Dane County Code of Ordinances is the County’s floodplain zoning ordinance. The ordinance covers the floodway, floodfringe and a general floodplain districts that fall within the floodplain boundaries as shown on FEMA’s Flood Insurance Rate Maps (FIRM). The floodplain ordinance regulates development in flood hazard areas for the specific purpose of protecting individuals, private property, and public investments from flooding and flood damage. County floodplain zoning applies only in the unincorporated areas of the County and does not require approval of town boards. Cities and villages must


adopt their own floodplain zoning ordinances. Towns in Dane County are covered by the County’s floodplain ordinance.

In general, the County’s floodplain zoning ordinance prohibits new residential construction in the floodway, regulates improvements to existing structures in the floodway, requires dry-land access to new developments in the floodfringe, and requires floodplain zoning permits for all development or redevelopment in the floodplain. The ordinance also restricts any development in the floodplain that would cause an obstruction to the flow of water or increase by more than .01 feet the height of the regional flood. Chapter 17 meets or exceeds the standards defined in NR 116.

Dane County’s flood insurance rate maps have recently been updated through the Map Modernization process. Digital Flood Insurance Rate Maps (DFIRMs) are available and made effective January 2, 2009.

Municipal Floodplain Zoning

Wisconsin state statutes and administrative code require that cities and villages adopt floodplain zoning ordinances as part of a statewide floodplain zoning program. The DNR has developed a model ordinance that includes both the minimum regulatory standards required by administrative code (NR 116) and those of the National Flood Insurance Program (NFIP).

All eight cities and 12 of the 14 affected villages in Dane County have adopted local floodplain ordinances. As of June 2009 seven municipalities within the County are currently not participating or compliant with the National Flood Insurance Program. Of those, four municipalities have mapped floodplains within their boundaries: the villages of Brooklyn, Deerfield, Rockdale, and Shorewood Hills. These four communities have all been sanctioned by the NFIP. Deerfield and Rockdale may participate in NFIP once a floodplain ordinance is adopted, though the need and desire for participation is low. Communities that do not participate in the NFIP are subject to the sanctions outlined in Section 202(a) of the Flood Disaster Protection Act of 1973. Section 202(a) makes flood insurance, federal grants and loans, federal disaster assistance, and federal mortgage insurance are not available for the acquisition or reconstruction of structures located in the floodplain shown on the Flood Insurance Rate Maps. Table 4.55 shows the level of NFIP participation of villages and cities in Dane County. Maple Bluff now has a floodplain zoning ordinance that meets NFIP standards, even though it has no Special Flood Hazard Area (SFHA), a change that became effective in January 2009. The Village of Blue Mounds has also recently joined the program in May 2009, even though it does not have a SFHA mapped. Shorewood Hills is working on entering this program. Communities that participate in the NFIP each have an objective that details how they will continue to comply with and implement the program. This is discussed more in Chapter 5 Mitigation Strategy.


Table 4.55 NFIP Participation Summary

Villages Floodplain Ordinance Comments

Dane County FIRM

Panels

NFIP Partici-pation

Init FHBM Identified

Init FIRM Identified

Curr Eff Map Date

Reg-Emer Date

Belleville Yes 731, 732 Yes 1/23/1974 11/19/1980 5/18/2009 11/19/1980

Black Earth Yes 169, 188 Yes 12/17/1973 1/2/1981 1/2/2009 1/2/1981

Blue Mounds Yes 350 Yes (NSFHA) (NSFHA) 5/14/2009

Brooklyn No Sanctioned by NFIP 775, 800 No 6/17/2003 5/18/2009

Cambridge Yes 494, 657 Yes 12/17/1973 6/4/1980 1/2/2009 6/4/1980

Cottage Grove Yes 456, 475 Yes 6/17/2003 1/2/2009 6/17/2003

Cross Plains Yes 356, 357 Yes 5/24/1974 2/16/1983 1/2/2009 2/16/1983

Dane N/A 50, 75, 225, 250 No (NSFHA) (NSFHA)

DeForest Yes 500 Yes 12/7/1973 9/1/1978 1/2/2009 9/1/1978

Deerfield No Sanctioned by NFIP

88, 90, 251, 252 Yes 6/17/2003 1/2/2009

Maple Bluff Yes Yes (NSFHA) (NSFHA) 1/15/2009

Marshall Yes 315, 320, 325 Yes 12/17/1973 12/16/1980 1/2/2009 12/16/1980

Mazomanie Yes 166 Yes 12/28/1973 12/1/1981 1/2/2009 12/1/1981

McFarland Yes 441, 443, 444 Yes 12/17/1973 6/15/1978 1/2/2009 6/15/1978

Mount Horeb N/A 375, 550 No (NSFHA) (NSFHA)

Oregon Yes 592, 611 Yes 5/24/1974 9/30/1980 1/2/2009 9/30/1980

Rockdale No Sanctioned by NFIP

494, 656, 658, 659 No 12/7/1973 12/16/1980 1/2/2009

Shorewood Hills No Sanctioned

by NFIP 404, 408 No 1/31/1975 6/1/2009 1/2/2009

Waunakee Yes Numerous –See index Yes 12/17/1973 5/1/1978 1/2/2009 5/1/1978

Cities Floodplain Ordinance Comments

Dane County FIRM

Panels

NFIP Partici-pation

Init FHBM Identified

Init FIRM Identified

Curr Eff Map Date

Reg-Emer Date

Edgerton Yes See Rock

County maps

Yes 12/17/1973 4/15/1982 1/2/2009 4/15/1982

Fitchburg Yes Numerous–See index Yes 9/18/1986 1/2/2009 8/23/2001

Madison Yes Numerous –See index Yes 3/8/1974 9/30/1980 1/2/2009 9/30/1980

Middleton Yes Numerous –See index Yes 12/14/1973 5/1/1980 1/2/2009 5/1/1980

Monona Yes Numerous –See index Yes 11/30/1973 6/15/1978 1/2/2009 6/15/1978


Stoughton Yes 640, 650 Yes 12/17/1973 6/15/1978 1/3/2009 6/15/1978

Sun Prarie Yes Numerous –See index Yes 11/4/1973 1/17/1991 1/4/2009 12/11/1995

Verona Yes 393, 394, 556, 557 Yes 12/7/1973 8/1/1980 1/5/2009 8/1/1980

Source: FEMA National Flood Insurance Program Community Status Book. Available online at http://www.fema.gov/cis/WI.html

Shoreland, Shoreland-Wetland, and Inland-Wetland Regulations

Section 59.612 of the Wisconsin statutes requires all counties to adopt shoreland zoning for all lands near navigable waterways. The Department of Natural Resources (DNR) has adopted an administrative rule (NR 115) that establishes the minimum requirements for all county ordinances adopted under this section of the law.

Chapter 11 of the Dane County Code of Ordinances is the County’s Shoreland, Shoreland-Wetland, and Inland-Wetland ordinance. This chapter sets minimum environmental standards for development in shoreland, shoreland-wetland, and inland-wetland zones. The ordinance regulates uses that are detrimental to these areas by restricting the removal of natural shoreland cover and controlling excavation, filling, and other earth-moving activity. The ordinance also defines minimum setbacks for buildings and other structures.

Under the County’s ordinance, the following definitions apply:

• A wetland is an area where water is at, near, or above the land surface long enough to be capable of supporting aquatic vegetation and has soils indicative of wet conditions;

• Shoreland areas are all lands in unincorporated areas of the County that are within 1,000 feet of the ordinary high water mark of a navigable waterway or lands within 300 feet of the ordinary high water mark or landward side of the floodplain of a navigable waterway; and/or

• An inland wetland is a wetland not located within a shoreland area.

The County’s shoreland zoning ordinance sets minimum environmental standards for development within 300 feet of navigable rivers or streams, within 1,000 feet of navigable ponds or lakes, and within mapped wetlands anywhere in the County. Development standards include:

• Minimum building setback of 75 feet from the ordinary highwater mark of all lakes, ponds, rivers, and streams;

• Measures to limit the amount of vegetation that can be removed near the shore; • Measures to conserve and protect wetlands; and • Requirements for erosion control and other management practices for construction near

the shore.

Like most County ordinances, the shoreland zoning ordinance currently applies only to the unincorporated areas of the County. For recently annexed lands, state statute does require that cities and villages apply standards that are at least as restrictive as the County’s.

Erosion Control and Stormwater Management Ordinance

The Erosion Control and Stormwater Management Ordinance was designed to help protect Dane County’s lakes, streams, wetlands and quality of life by reducing the negative impacts of sediment, rainfall, melting snow and other water runoff. The ordinance establishes countywide standards for the quantity and quality of water that runs off land under


construction in urban and rural areas, including farms. It also provides flexibility in meeting those standards, recognizing the unique characteristics of each project and site. The Erosion Control and Stormwater Management Ordinance builds on the construction site erosion control requirements that have been in effect since 1995. The ordinance was adopted in 2001 by the Dane County Board and implemented in August 2002 through Chapter 14 of the Dane County Code.) The ordinance is not limited to unincorporated areas; it also applies in cities and villages. The ordinance is administered by Dane County for unincorporated areas and cities and villages that have not adopted standards at least as restrictive as the County’s. Cities and villages that have developed their own standards that meet or exceed the County minimums administer these standards locally.

Effective January of 2006, revisions to the erosion control and stormwater management ordinance were made to meet state standards for infiltration and to make shoreland erosion control requirements of Chapter 11 consistent with Chapter 14. Dane County chose to adopt the state’s infiltration standards, with few modifications. One significant change was a sunset date for the caps that limited that amount of area required to be dedicated to infiltration (State rules require only one percent of a residential site and two percent of a nonresidential site to be dedicated to infiltration). The other significant change was the elimination of the design storm approach (utilizing TR-55) to meet the infiltration requirements. The Dane County Lakes and Watershed Commission also assembled an infiltration taskforce to explore regulatory alternatives to caps and evaluate stormwater infiltration in Dane County. The taskforce included members from the academic, development, municipal, regulatory communities, and watershed groups. After nearly a year of work, the taskforce returned to the Dane County Lakes and Watershed Commission with a full report including a unanimous recommendation to remove the caps and include an alternative recharge performance standard. The revised infiltration requirements were adopted in August of 2006, and are now effective.

Land Division and Subdivision Regulations

Chapter 75 of the Dane County Code of Ordinances contains the County’s land division and subdivision regulations. The ordinance applies in all unincorporated areas as well as incorporated areas that have entered into agreement with the County for cooperative exercise of the authority to approve subdivision plats. The ordinance defines platting procedures and permitting, design standards, improvement requirements, and land suitability requirements.

The Land Suitability section of the ordinance gives the Zoning and Natural Resources Committee of the County Board the authority to restrict division or subdivision of land that is unsuitable for development due to flooding or potential flooding, soil limitations, inadequate drainage, or other conditions likely to be harmful to the health, safety or welfare of future residents or users of the area, or harmful to the community or the County.

Flood Emergency Response

Dane County’s Emergency Operations Plan (EOP) describes the County’s response to major emergencies and disasters. The purpose of the EOP is to:

• Facilitate the protection of lives, property, and the environment in major disasters; • Coordinate response to disasters, assess damages, identify mitigation opportunities, and

implement recovery efforts;


• Describe the County’s relationship in support of local units of government during response and recovery;

• Describe the roles and responsibilities of County agencies and departments in responding to disasters; and

• Provide a link between the County and local response plans.

The plan reflects an all-hazards approach to disaster preparedness and response, but has been implemented for flood events on numerous occasions in the past decade. In addition to the Basic Plan the following emergency support functional (ESF) annexes are included:

• ESF 1 (Evacuation/Transportation) • ESF 2 (Communications) • ESF 3 (Public Works/Engineering) • ESF 4 (Fire Fighting) • ESF 5 (Emergency Management) • ESF 6 (Human Services) • ESF 7 (Resource Support) • ESF 8 (Public Health) • ESF 9 (Urban Search and Rescue) • ESF 10 (Hazardous Materials) • ESF 11 (Agriculture) • ESF 12 (Energy) • ESF 13 (Public Safety) • ESF 14 (Long Term Recovery) • ESF 15 (External Affairs)

4.4.3 Regulatory Structure

Understanding the regulatory structure that determines how land will be developed and conserved in the State of Wisconsin and Dane County is necessary in understanding how future land will be used. Reviewing current regulations will also allow the County to build on current laws and avoid redundancies.

Management Agencies: Federal and State

Federal Emergency Management Agency (FEMA)

FEMA oversees all emergency management activities in the United States. A sample of its operating goals is to: reduce loss of life and property; minimize suffering and disruption caused by disasters; prepare the nation to address the consequences of terrorism; and serve as the nation’s portal for emergency management information and expertise.

Wisconsin Department of Emergency Management (WEM)

WEM oversees the State’s three Hazard Mitigation Programs: The Hazard Mitigation Grant Program, The Flood Mitigation Assistance Program, and the Pre-Disaster Mitigation Program. WEM collaborates with state and federal entities through the Interagency Disaster Recovery Group (IDRG) and with other state agencies through the State Hazard Mitigation Team (SHMT) in order to improve Wisconsin’s disaster resistance. The SHMT developed the State of Wisconsin Hazard Mitigation Plan to carry out actions identified to reduce vulnerability to hazards throughout Wisconsin. This plan recommends actions at the state level.


Wisconsin Department of Natural Resources (DNR)

By State law and administrative rule, the DNR sets standards and regulates water resources in Wisconsin. The DNR’s oversight extends to setting standards that the County, local units of government, and individual landowners must conform to for floodplain management, shoreland management, dam safety, waterways and wetlands, and surface and groundwater quality.

Department of Agriculture, Trade, and Consumer Protection (DATCP)

By state law and administrative rule, DATCP sets soils and water conservation standards. Statutes also create county land conservation committees and departments and establish soil and water conservation program requirements that each county must meet. DATCP rules also provide cost sharing opportunities and encourage coordination of soil and water conservation planning and program implementation.

Management Agencies: Regional

Capital Area Regional Planning Commission (CARPC)

The CARPC provides a comprehensive, long-range, and areawide planning perspective to governmental decision-making in the region. The Commission’s plans are implemented through actions taken by other units. It works closely with town, village, city, county, and state agencies as a means of sharing technical resources to help achieve coordinated plans and development. It provides information, helps local units with their planning and coordinates programs in the region.

Management Agencies: Local Governments

Local Units of Government

The State of Wisconsin has four levels of local government, county, city, village, and town. Dane County contains eight cities, nineteen villages, and thirty-four towns. Only the towns or unincorporated areas are under the County’s zoning jurisdiction.

Management Agencies: Special Districts

Sanitary Districts

Town sanitary districts are created for the purposes of constructing and operating public water supply, sewage treatment, storm sewers, drainage improvements, and solid waste disposal facilities. The districts have the power to acquire property, levy special assessments, and collect charges for services.

Drainage Districts

The drainage district program oversees the systematic drainage of lands for agricultural practices. Nearly one third of Wisconsin’s 79,000 farms use drains to remove excess water from the land, primarily through small-scale drains. These drains are organized into drainage districts. Within Dane County primary responsibility for planning for and


administering drainage districts resides with the Dane County Drainage Board. The board also resolves drainage disputes among landowners.

Inland Lake Protection and Rehabilitation Districts

Inland lake protection and rehabilitation districts (lake districts) are special purpose units of government administered by a local board of commissioners. Lake districts are authorized by Wisconsin State Statute Chapter 33, subchapter IV. Lake districts have the authority to levy taxes, make special assessments, or charge user fees to finance lake management activities. A lake district can assume responsibilities for ownership, repair, maintenance and operations of a dam. District voting members make major policy decisions at annual meetings. There are approximately 80 inland lake protection and rehabilitation districts throughout Wisconsin. The DNR administers a number of financial assistance programs designed to assist lake districts in their planning and protection efforts. These include Lake Planning Grants and Lake Protection Grants. Many lake districts and local governments have used these assistance programs to support land use planning and growth management efforts as a means of protecting lake water quality.

Management Agencies: Dane County Departments, Commissions, and Committees

Emergency Management Department

This department provides and improves public safety by enabling individuals, groups, and communities to effectively plan for and manage hazards associated with major emergencies and disasters. These potential hazards include natural hazards, terrorism, and hazardous materials. This department is the lead agency in devising the hazard mitigation plan.

Highway and Transportation Department

In order to meet the public’s need for access and freedom of movement, the Dane County Highway and Transportation Department designs, coordinates, and maintains transportation systems that are: (1) safe for both workers and the general public; (2) responsive; (3) efficient; (4) effective; (5) environmentally sound; and (6) financially responsible.

Dane County Land & Water Resources Department - Land Conservation Division

The Dane County Land & Water Resources Department - Land Conservation Division coordinates soil and water conservation efforts in the County. The Department is also responsible for technical matters in the implementation of the County’s Erosion Control and Stormwater Management ordinance. This department manages the lake levels for Lakes Mendota, Monona, Waubesa, and Kegonsa, through dams at Tenney, Babcock, and LaFollette Parks. The lake level and flow orders are set by the DNR. In addition, the Department is currently providing contractual services to five municipalities in Dane County to assist them with the enforcement and implementation of local ordinances.


Lakes and Watershed Commission

The Dane County Board established a permanent Lakes and Watershed Commission in 1988. The Wisconsin State Legislature defined the Commission's special powers, composition, duties, and organization in 1990. A coordinating and advisory agency within Dane County government, the Commission's charge is to protect and improve water quality, as well as the scenic, economic, recreational, and environmental value of Dane County's water resources.

Parks Commission

The Parks Commission manages the County parks and open space system, in conjunction with the Dane County Land & Water Resources Department - Parks Division. In that role, the commission oversees the County’s Parks and Opens Space Plan, and acquires property to further the goals of that plan.

Zoning and Land Regulation

The zoning & land regulation committee shall have the duty and responsibility to: (1) Act as the supervisory committee for the planning and development department, including survey, zoning, tax description and plat review functions. (2) Act as the policy oversight committee for register of deeds, the Dane County Board of Adjustment and the Dane County Regional Planning Commission (with respect to land use matters), and zoning and land use regulations activities for lakes management. (4) Fulfill the zoning and subdivision control powers and duties enumerated in chapters 10, 74, 75 and 76, D.C. Ords. (5) Advise the county board on all matters relating to zoning, land use and land regulation. (6) Report to the county board regarding all proposed cemetery maps and plats in accordance with sec. 157.07, Wis. Stats.

Environment, Agriculture, and Natural Resources Committee

The environment & natural resources committee shall have the duty and responsibility to: (1) Act as the supervisory committee for extension, land conservation, and the lakes & watershed commission (for budget review purposes only). (2) Act as the policy oversight committee for the Dane County Parks Commission, operational programs and budget for lakes management and aquatic weed control, and the Dane County Humane Society. (3) Advise the county board on all matters relating to agriculture and the conservation of natural and environmental resources in Dane County, and confer and cooperate with any other agency interested in environmental quality and conservation. (4) (a) Provide policy direction and guide implementation of county planning efforts and organizational structure, including the county executive’s proposals on growth and development, the Dane County Land Use and Transportation Plan, and the respective roles of the regional planning commission, metropolitan planning organization and department of planning and development. (b) Facilitate regular, ongoing communication, including holding listening sessions with Dane County’s cities, villages, and towns on developments of regional impact. (c) Review current county policies, plans and ordinances related to land use and development to determine whether revisions are necessary, and work with other county board committees to develop necessary changes. (d) Recommend policy and planning initiatives to the board and the planning director. (e) Monitor state land use planning efforts


and make recommendations on land use and development issues to the executive committee regarding the county’s legislative agenda. (5) Cooperate with the Dane County Board of Health, the Dane County Regional Plan Commission, the Wisconsin Department of Commerce and the department of natural resources on all matters relating to water resources and pollution control, as appropriate. (6) Assume the duties and responsibilities of the former Strategic Growth Management Committee, as defined by any county board resolutions or ordinance amendments previously adopted.

Land Conservation Committee

The land conservation committee is established pursuant to chapter 92, Wis. Stats., which requires that each county have such a committee. The committee coordinates all matters relating to agriculture and soil and water use and conservation in the county, including the development of standards and specifications for management practices to control erosion, sedimentation and non-point source water pollution.

Plans

State of Wisconsin Hazard Mitigation Plan

The purpose of the Plan is to identify Wisconsin’s major hazards, assess the vulnerability to those hazards, and take steps to reduce that vulnerability using the technical and program resources of Wisconsin State agencies. The Plan strives to help protect the health, safety, property, environment, and economy of Wisconsin from the effects of natural hazards. Moreover, FEMA requires states to submit a hazard mitigation plan as a condition for receiving disaster assistance and Wisconsin’s plan fulfils that requirement.

The State Hazard Mitigation Plan is a natural hazard mitigation plan. Technological hazards are not addressed. The Plan assesses hazard risk, reviews current state level hazard mitigation capabilities, develops mitigation strategies, and identifies state agency actions to address mitigation needs. The Plan does not attempt to develop local mitigation projects. As a home rule state, the state respects the right of communities to implement specific mitigation actions that best serve them. The Plan identifies existing resources to assist local governments in their mitigation efforts and develops new tools to further mitigation at the local level. This is accomplished by establishing statewide mitigation policies, providing technical resources through state agency staff expertise and support, providing financial assistance through various programs, training, education, and other agency initiatives.

Dane County Comprehensive Plan (2007)

In 2000, the Wisconsin Legislature passed the most complete comprehensive planning legislation in Wisconsin’s history. Often referred to as “Smart Growth,” the law requires all Wisconsin communities that exercise land use authority to adopt a comprehensive plan by ordinance by 2010, and for land use decisions to be consistent with the adopted plan.

In October 2007, Dane County adopted the Dane County Comprehensive Plan. This plan focuses on development that meets the needs of the present without compromising the ability of future generations to meet their needs. The Dane County Comprehensive Plan


was developed in accordance with the state legislation, and is comprised of nine required elements that significantly affect all communities. The nine elements of the plan are:

1) Issues And Opportunities;

2) Housing;

3) Transportation;

4) Utilities And Community Facilities;

5) Agriculture, Natural And Cultural Resources;

6) Economic Development;

7) Intergovernmental Cooperation;

8) Land Use; and

9) Implementation.

The structure of this plan recognizes and respects the statutory authority granted to different units of government. This is reflected throughout the plan in the formation of goals, policies, and objectives as they may relate to the County’s jurisdiction in any given area. For example, state law limits the County’s zoning authority to unincorporated areas, and requires joint decision-making with town governments. So, while this plan may include goals and objectives aimed at influencing land use decisions in cities and villages, inclusion in the plan alone will not yield the desired results. Rather, it will take concerted inter-governmental cooperation efforts to achieve them. In fact, achieving and implementing many of the goals, objectives, and policies of this plan will require a significant degree of coordination among different units of government.

While the Dane County Comprehensive Plan is not fully and truly a hazard mitigation plan, it does set forth a plan for cooperative planning among multiple layers of jurisdictions within Dane County. It also parallels the Multi Hazard Mitigation Plan in that it requires, by Wisconsin statute, that all following plans consult a master document for existing County policies and procedures, and apply those policies accordingly.

Dane County Land Use and Transportation Plan (1997)

In 1997, the Dane County Board of Supervisors adopted the Dane County Land Use and Transportation Plan as part of the official Master Plan for Dane County (as provided for by Wis. Stats. §66.0309(9) and (10)). The plan serves as guide for land use and transportation system development, as well as a basis for review of proposed projects by local units of government, and appropriate state and federal agencies.

The Dane County Land Use and Transportation Plan is the overall comprehensive land use and development policy framework and guide for Dane County, and replaced the 1985 Regional Development Guide, and the 1973 Dane County Land Use Plan, which provided similar policy framework previously. The objective of planning in Dane County has been to develop more detailed plans for specific geographic areas (such as city, village, and town master plans) or plans for specific functional or subject areas (such as the Dane County


Water Quality Plan, Farmland Preservation Plan, Parks and Open Space Plan, etc.) consistent and in the context with the framework provided by the Dane County Land Use and Transportation Plan’s policies and objectives.

Dane County Water Quality Summary Plan (2004)

In 1975, the Governor designated Dane County as an area with complex water quality problems, and the DCRPC as the local representative planning agency charged with developing an areawide comprehensive water quality management plan for the region. The DCRPC worked with federal, state, and local management agencies over several years to develop the initial Dane County Water Quality Plan (including 11 technical appendices). The plan was adopted and certified by the state in 1979 as the official area-wide water quality management plan for Dane County, and has been continuously revised, updated, and expanded since then. The plan provides a policy framework and guidance for federal, state, and local water quality protection programs in Dane County.

Dane County Parks and Open Space Plan

The overall goals of this plan are to preserve key natural resources of the County in permanent open space, provide sufficient parks and recreation areas to meet the needs of the residents of Dane County, preserve for posterity the nature and diversity of the natural and cultural heritage of Dane County, and use open space to achieve separation of communities and help guide urban growth when the land is appropriate for park purposes.

Dane County Farmland Preservation Plan (1981)

The Dane County Farmland Preservation Plan was adopted in 1981 as part of Dane County’s Master Plan in order to manage the conflicts between urban and rural needs for land. To that end it aims to: 1) identify and preserve valuable agricultural land in the County; 2) delineate and conserve natural resources; and 3) identify those areas where new urban growth should be directed. This plan derives its authority from County Development Plans, and Agricultural Preservation Planning, and Regional Planning statutes.

Ordinances

General Zoning

Cities and villages in Wisconsin have general zoning powers, and act independently from Dane County. Under state statutes, the County board has the authority to pass a general zoning ordinance including text and maps or zoning districts in unincorporated areas. This map and text becomes effective in an individual town when the town board votes approval for the County ordinance text and zoning district map for the town. All towns in Dane County have adopted Dane County’s zoning ordinances. The town board also has an opportunity to approve of disapprove of all subsequently proposed text and map amendments to the County zoning ordinance, of the change affect the town.


Land Subdivision

Wisconsin law allows any city, village, town, or county that has a planning agency to adopt a land division ordinance. Wisconsin has only one local enabling law for local subdivision regulation. This enabling law allows towns to adopt their own subdivision ordinance without Dane County approval. Similarly, Dane County does not need town approval for the County subdivision regulations to apply within that town. City and village subdivision regulations may also be applied to the unincorporated areas, which fall within the extraterritorial plat approval jurisdiction of the city or village.

Extraterritorial Zoning

Zoning power extends beyond the borders of cities and villages in Wisconsin. A joint committee, consisting of three city or village plan commission members and three town members must approve of the extraterritorial zoning plan and regulations by majority vote. Any city or village that has a plan commission may exercise extraterritorial zoning power in the unincorporated areas surrounding the city or village.

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