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Developing a LakeManagement Plan

Prepared by the InteragencyLakes Coordinating Committee

Contributing agencies:

Minnesota Board of Water and Soil ResourcesMinnesota Department of Natural ResourcesMinnesota Pollution Control AgencyMinnesota Department of Agriculture

With participation by

Minnesota Lakes AssociationMetropolitan CouncilHennepin Parks

August 1996

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Foreward

Thank you for wanting to know how to bettermanage your lake. Lake management mustbe a collaborative process involving allinterested parties —along with quite a fewtechnical specialists— to be successful. Thispublication is designed to help you besuccessful in your lake management efforts.

“Developing a Lake Management Plan” is acompanion document to the Minnesota Lakeand Watershed Data Collection Manual,published by Minnesota’s EnvironmentalQuality Board Lakes Task Force. The goal of“Developing a Lake Management Plan” is tohelp you develop a lake management planthat has specified goals for local, county andstate governmental units and organizations. Itis likely that the lake management plan willbecome a critical tool in focusing limitedpublic attention and resources for your lake.

Since every lake management plan demandsgood data on which to base sound decisions,the Data Collection Manual should be readfirst. Data collection should be well underway before attempting to prepare a lakemanagement plan.

We also would appreciate your commentsand suggestions on how to improve this

manual, or any lake-related managementservices. Your input is very important to us.Please address your comments to: Chair,Minnesota Interagency Lakes CoordinatingCommittee, and send to any of the following:

Commissioner, Minnesota Department ofNatural Resources500 Lafayette RoadSt. Paul MN 55155

Commissioner, Minnesota Pollution ControlAgency520 Lafayette Road.St. Paul MN 55155

Executive Director, Minnesota Board ofWater and Soil ResourcesOne West Water Street, Suite 200St. Paul MN 55107

Commissioner, Minnesota Department ofAgriculture90 West Plato BoulevardSt. Paul MN 55107

Chair, Metropolitan Council230 East 5th StreetSt. Paul MN 55101

For additional copies, contact the Minnesota Board of Water and Soil Resources, One West WaterStreet, Suite 200, Saint Paul, MN 55107 (612) 296-3767.

The Interagency Lakes Coordinating Committee(ILCC) has guided the work on this manual. TheILCC was formed by a memorandum of agree-ment between the Minnesota Department ofNatural Resources (MDNR), the MinnesotaPollution Control Agency (MPCA), the MinnesotaBoard of Water and Soil Resources (BWSR), theMinnesota Department of Agriculture (MDA) andthe Metropolitan Council (Met Council) in 1993to improve the coordination of lake managementand planning activities of these agencies. TheMinnesota Lakes Association (MLA) has alsobeen an active ad hoc participant in the ILCC.The ILCC formed committees to work on both theLake and Watershed Data Collection Manual andthis planning manual. In October 1994, the EQBLakes Task Force merged with the ILCC and iscontinuing to implement the recommendations ofthe Lake Management Forum (started in 1991).

This document represents a collaborative effortamong the aforementioned parties and does notnecessarily reflect the policies of the individualagencies or divisions within an agency.

The committee is grateful to all the agency staff,local units of government staff and lake associa-tion members whose encouragements, hard workand support contributed to this project. The BWSRdeserves special acknowledgment for their workediting and printing the document. We are hopefulthat such teamwork will continue as lake manage-ment planning moves forward to protect andenhance the qualities of Minnesota lakes.

The Minnesota Interagency LakesCoordinating Committee

August 1996

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Table of contents

I. Introduction ................................................................................................ 4

II. Planning: A model framework for lake management plans................... 5A. Getting Started ...........................................................................................................5

1. Form an advisory group.2. Appoint a citizen steering committee3. Assemble a technical committee4. Educate the steering committee

B. Gather Information ................................................................................................... 71. Physical and biological characteristics2. Land use characteristics3. Social/demographic trends

C. Identify and set priorities ......................................................................................... 7D. Develop goals, objectives and actions ..................................................................... 8E. Implementing and monitoring progress ................................................................... 8

III. Overview: Factors influencing lake management .................................. 9A. Regional patterns ...................................................................................................... 9B. The lake-watershed connection ................................................................................10

1. Watershed size2. Watershed hydrology3. Precipitation4. Soils5. Land use

C. Lake water quality monitoring and assessment .......................................................121. Common sampling procedures2. Common stream sampling procedures3. Fish community structure as an indicator of water quality

IV. Lake Management Focus Areas .............................................................. 14A. Water Quality ...........................................................................................................14B. Fisheries management plans ....................................................................................15C. Aquatic vegetation ...................................................................................................16D. Wildlife ....................................................................................................................18E. Exotic species ...........................................................................................................19F. Land use and zoning ................................................................................................21G. Managing water surface use conflicts ......................................................................22H. Public water access ..................................................................................................24

V. Conclusion .............................................................................................. 25

VI. References .............................................................................................. 25

Appendixes - (not avaible with PDF - out of date)Appendix A – Water quality indices

Carlson Trophic IndexFish Community Structure Graphs

Appendix B - Lake water quality benchmarks based on ecoregion

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I. Introduction

Water... Lakes... Fishing... Swimming...Canoeing... Cabins.... these words bring tomind the fundamental Minnesota experience.We take the abundance and diversity of ourlakes, rivers and wetlands for granted.—andwith good reason: Minnesota has more than15,000 lakes that are 10 acres or larger. Morethan 5,000, covering more than three millionacres, are actively managed for their fisher-ies. Many others are used for boating,waterskiing, hunting and swimming, and justplain appreciated for their beauty.

The excitement of the walleye opener, aweek-long vacation at the cabin, the solitudein the Boundary Waters Canoe Area, or therelaxation from a walk around a lake in a citypark all speak to the special relationshipMinnesotans have with lakes. Thanks tothem, travel and tourism is our second largestindustry. With 208,000 miles of shoreline,Minnesota offers more waterfronts than thestates of California, Florida and Hawaiicombined!

In 1986, the 28 million visitors who traveledto and through the state generated nearly $7billion in revenues. About 73 percent werevacationers, with outdoor activities ratedhigh on their lists of preferred activities.

Keeping our lakes clean directly relates toMinnesotans’ ability to compete with re-gional lake centers such as northern Wiscon-sin, Ontario and Michigan for these relatedindustries and income sources, which in turncontribute to local schools, roads, healthprograms, social services and law enforce-ment services and infrastructures.

Lakes cannot manage themselves.In order to maintain these beneficial uses,lakes need help. With ever increasing recre-ational use and growing populations residingnear and along waterways, lakes can sufferfrom small and large cumulative impacts andcannot manage themselves. We affect ourlake by our actions within the lake, along itsshorelines and well up into the lake’s water-shed or drainage basin. Even distant areas canbe connected to the lake by the downstreamflow of waters which, in turn, carry pollut-ants, sediments and nutrients into the lakeover time. We all are part of the problem, butwe all can do something, no matter howapparently insignificant (e.g., recycling ofhousehold materials), to help our lakes. Lakesneed to be systematically and purposefullymanaged over time if we are to sustain theirlong-term health and viability.

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A. Getting Started

Appoint a citizen steeringcommittee.The job of the steering committee is to definethe citizen advisory group’s concerns, toeducate themselves and the larger community

on the sources and dimen-sions of the concerns, and toidentify, study and recom-mend possible solutions. Thework of the steering commit-tee must be fair, objectiveand impartial for it to beaccepted and put into actionby the larger community.

The size of the steering committee may vary,but it needs to be workable. Include represen-tatives appointed from local and countygovernments. Designate a chairperson who iswell respected by diverse groups and able toforge partnerships. The committee shouldchoose when and where it will meet. It is agood idea to set target completion dates for

committee work so that there is a definedtime commitment for members. In addition, aseparate technical committee may be estab-lished to advise the steering committee.

Form an advisory group. Identify the parties interested in the manage-ment of the lake and the lake’s watershed.Invite all legitimate groupswith an interest in the lakeresource to participate in acitizen advisory group. It isparticularly important toinclude people or organiza-tions that may not believethere is a need to develop alake management plan.While it may make initial contacts or meet-ings more difficult, considering all sides willlead to better solutions and implementation.Excluding some interests and viewpoints maylead to a future sabotage of the plan and cankeep good resources or ideas away.

II. Planning: a model framework for lakemanagement plans

tion of a citizen steering committee thatorganizes a lake management planningadvisory group, with membership from alllegitimate lake and watershed groups.

Lake management planning must includemembers representing diverse interests andperspectives to reduce the risk of failing. Theactivities of the citizen steering committeerequire that its members have the time todedicate to make the effort successful; manygroups have formal rules of attendance forvoting and participation.

The typical lake management steering com-mittee member may need to dedicate one tothree years (or more) toward the effort.Attending meetings once or twice a month isan important aspect of being a steeringcommittee member.

Lake management plans help protect naturalresource systems, including the water qualityof the lake and the associated fish, vegetativeand wildlife communities. A lake manage-ment plan:

� Encourages partnerships between con-cerned citizens, including lakeshoreowners, watershed residents, resourcemanagement agencies and special interestgroups.

� Identifies the concerns that the people feelare important to address.

� Sets realistic goals, objectives and actions.

� Identifies needed funds and personnel.

The planning process starts with the forma-

Citizensteeringcommittee

Advisorygroup

Developing a Lake Management Plan

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Assemble a technical committee.Formally request assistance from local,regional, state and federal governmentalgroups to appoint staff to a technical commit-tee. The technical committee will advise andassist the steering committee on all technicalissues.

Suggested contacts fortechnical assistance

State Agencies such asMPCA and MDNR regularlycollect information on waterquality, fish populations andother natural resources.Contact your area or regionaloffice.

Local Units of Government (LGUs) includ-ing counties, soil and water conservationdistricts and watershed districts, may alsocollect land and watershed information andhave land use, ownership and tax informa-tion.

Local lake associations and volunteers.

Federal Agencies such as the Natural Re-sources Conservation Service (NRCS).

Private consulting services and commercialenterprises.

Educate the steering committee.Effective planning starts with an understand-ing of the technical, social, economic anddemographic factors influencing a lake.Understanding the historical and currentconditions, along withprojected future conditions,will also help establisheffective goals and objec-tives and identify theappropriate actions toaddress the interest group’sconcerns.

Review all pertinent re-source plans before beginning to develop alake management plan. These plans willprovide some of the data needed, andy mayidentify goals, objectives and actions appro-priate for the lake. Resource plans include,but are not limited to,

✓ local land use plans (zoning controls);✓ comprehensive local water management

plan;✓ lake assessment studies;✓ MDNR fisheries management plans;✓ watershed district plans; and✓ soil and water conservation district

comprehensive plans.

(Please refer to appendix A for informationon how to contact local County WaterPlanners, DNR Area Fisheries and AreaWildlife Offices, and MPCA state and re-gional offices.)

Plan on the education phase extending over asix- to 12-month period. Mandatory atten-dance at the educational meetings is neces-sary in order to effectively identify thechallenges and opportunities to be addressedby a lake management plan.

Technicalcommittee

Successful Steering Committees

Focus on the concerns identified,rather than assigning blame.

Resolve from the beginning to worktoward common goals and under-standing.

Are willing to set aside differenceswhile working on areas wheresolutions seem possible.

Treat all members of the committeewith respect.

Recognize that resource damage ofthe past and present are oftenunintentional, and often result fromlack of knowledge or information.

Work for consensus, so that everyonewill be committed to the actionsproposed.

Make field trips and site visits toclarify problems and solutions andincrease team cohesion.

Focus on specific, constructive actionsthat work, not on global environmen-tal problems.

Know that nothing inspires peoplelike success— they get a few deci-sions made as soon as possible.

Have some fun—and appreciate thecontributions of all involved in atangible way.

Education

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B.Gather InformationLake management planning entails gatheringdata about the lake and the watershed,including the physical features, land use andsocial trends. Please refer to The MinnesotaLake and Watershed Data Collection Manualfor specific instructions on gathering infor-mation. Important data typically includes:

1. Physical, chemical and biologicalcharacteristics

a. Delineate the watershed boundary.Calculate the watershed to lake surface area.

b. Identify the watercourses within thewatershed. Include streams, drainage ditches,tile lines and city storm water or sewer linesthat drain into and out of the lake.

c. Identify the soil types and slopes withinthe watershed.

d. Identify the lake size, depth, bottomcontours, structures and surrounding ground-water levels.

e. Identify fish populations.

f. Identify the aquatic vegetation.

g. Identify exotic plant species within thewatershed.

h. Identify endangered, threatened or rareplants, animals or natural communities (seeReference Section–Other for information onrequesting data from the Minnesota Depart-ment of Natural Resources).

2. Land use characteristicsa. Historical: Determine the presettlementdrainage patterns, wetlands and vegetation.

b. Current: Identify areas where pre-settlement conditions still exist. Identifyagricultural lands, urban and residential landsand recreation lands, and any other pertinentuses.

c. Future: It is important to plan for activi-ties that are likely to develop in the future.

3. Social and demographic trendsLook at the economic activities taking placewithin the watershed and consider how theycan be sustained, or even improved, withsuccessful lake and watershed management.Also learn about the attitudes of people livingin (or using the resources of) the lake’swatershed. Do the majority perceive aresource problem? What is the present andprojected population of the watershed, andwhere is it concentrated?

C. Identify concerns, setpriorities.

Most efforts to improve the quality of a lakebegin with an identified concern or problem.These concerns must be articulated as clearlyas possible to motivate citizens to take theactions needed.

Have the advisory group members identifyand list all concerns regarding the watershed’snatural resources and economic trends thathave an impact on quality or use.

Following are examples of concerns that canbe identified through a survey. The number inthe parenthesis indicates how often theconcern was identified by the 108 stakehold-ers surveyed:

Fish harvest has been declining over the lastdecade (42).

The lake is frequently covered with scum (32).

The watershed is contributing large amountsof nutrients and sediment to the lake (24).

Private septic systems are a problem (20).

Jet skis are ruining the lake (17).

Farmers in the watershed must be able tomake a living (12).

Have the advisory group members assess andprioritize the concerns. Use criteria such as:

Is the group able to change the situation?

Is the group motivated enough to address theconcerns?

Will the costs outweigh the benefits?

Use the inventory informa-tion to determine the criticalareas in need of manage-ment. Target the manage-ment efforts to the areasthat will benefit the mostand where the group’s inputwill make the biggestdifference.

After the concerns havebeen identified and priori-tized, develop a visionstatement.

Sample vision statement:The natural watershed processand functions are beingrestored to reduce nutrientand sediment loads deliveredto Great Lake by at least 60percent. The health andquantity of aquatic plantcommunity in the lake aregood and getting better andcovers 75 percent of the lakeshoreline. The lake is attractinganglers and other waterrecreational activities.


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D. Develop goals,objectives and actions

Once the problems are identified and priori-tized, set goals and objectives to address thehigh priority problems. Finally, identifyactions to achieve the goals and objectives.Staff and budget constraints may affect thenumber of goals established for the lakemanagement plan.

1. Establish goals, objectives andactions.

a. Goals are general statements relating towhat the group hopes to accomplish over thelong term. They are achievable.

Examples: Protect and improve the waterquality of Great Lake by reducing thenonpoint pollution entering the lake from thewatershed.

Reduce in-lake phosphorous concentrations.

b. Objectives convey what the grouphopes to accomplish in the near term to makeprogress toward the goal. They are specificand measurable.

Examples: By the year 2000, nutrient andsedimentation delivery rates to Great Lakewill be reduced by 40 to 60 percent fromcurrent levels.

By the year 2004, the in-lake phosphorous

level will be reduced to 30µg/ (+/- 10µg/l.)

c. Actions are the specific steps that willbe taken to accomplish the objective. They arerealistic and results-oriented.

Examples:

1. Identify land parcels in the watershedwhere the estimated erosion rate annuallyexceeds twice the tolerable soil loss limit (T).

2. Identify land parcels adjacent to streamsand tributaries where erosion exceeds thetolerable soil 2. loss limit.

3. Identify the owners of the parcels identifiedin actions 1 and 2.

4. Develop farm management plans on 80percent of the acres identified in action 1.

5. Implement best management practices (forwater quality) to control erosion within T on75 percent of the acres planned.

6. Retire 75 percent of the acres identified inactions 1 and 2 from row-crop production.

7. Develop grazing management plans for allacres identified in actions 1 and 2 that arebeing pastured or will be converted to pastureland.

8. Identify steep slopes and bluffs and anyknown erosion problems.

9. Identify areas unsuitable for developmentand work with the county planning and zoningoffice to restrict development of these areas.

10. Inventory existing septic systems onshoreland property.

11. Identify existing shoreland development by

types (e.g., permanent residence, seasonalresidence, business, etc . . . ).

E. Implementing andmonitoring progress

Prioritize actions based on the likelihood thatthey can be accomplished within the speci-fied timeframe, and their importance inachieving identified objectives.

Identify who is responsible for coordinatingand completing each action. Include the

timeframe for completion and the estimatedcost for the action.

Seek and secure required funds.

Determine appropriate measurements to useto monitor progress.

Report progress that has been made to theinterested parties identified in section I of thisoutline.

Frequently review and update the lakemanagement plan.

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III. Overview: factors influencing lakemanagement

Western Corn Belt Plains

A. Regional patternsMinnesota brings to mind pristine lakesinhabited by loons, bountiful populations ofwalleyes and canoe-traveling visitors, butthis picture does not reflect the naturalvariability of lakes found across the state.They range from the cold, deep waters of thenorthern boreal forest to the warm, shallowlakes of the southwest prairies. The northeastregion’s rocky landscape, nutrient-poor soils,forest cover and frequent rainfall haveresulted in lakes with clear water, while thelakes of southern Minnesota have evolved innutrient-rich soils. These southern lakesreceive considerably less rainfall than theirnorthern counterparts and are often murky.

Recognition of regional patterns and limita-tions helps put the characteristics and condi-tions in a particular lake and watershed intoperspective. More than 30 years of monitor-ing by state agencies and citizen volunteersgives us a good understanding of the regionalpatterns in Minnesota’s lake water quality.Seven ecoregions have been identified in thestate based upon land use, soils, geology andnatural vegetation patterns. Four of the sevenecoregions include 98 percent of the state’slakes (see below: Northern Lakes and Forests(NLF); North Central Hardwood Forests(NCHF); Northern Glaciated Plains (NGP)and the Western Corn Belt Plains (WCBP).

Minnesota’s ecoregions

NorthernGlaciatedPlains

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Table 1: Land use patterns by ecoregion. Percent of 40 acre parcels with land use characteris-tics. Based on 1968-1969 land use data from the State Planning Information Center.

Land Use %NLF %NCHF %WCBP %NGP

Cultivated 4.6 49.3 82.9 83.7

Forested 75.2 15.9 3.5 0.7

Water and Marsh 10.6 8.1 1.7 2.9

Pasture and Open 7.3 21.4 10.0 11.4

Developed 1.9 5.2 1.8 1.2

Developed by Heiskary and Wilson (1989; 1990)

Soils, geology, land cover, the intensity ofland use and other factors determine theamount of sediments and nutrients lost inrunoff waters per acre of land. Forested andwetland areas generally retain sediments andnutrients quite well. In contrast, urban andagricultural areas can have the greatest lossrates unless reasonable corrective measuresare established. Looking at broad ecoregionareas, the loss rate of phosphorous variesfrom about 0.1 kilogram phosphorus perhectare per year (or about 0.1 pounds peracre per year) in the NLF to about 0.8kilogram per hectare per year (or about 0.7per acre per year) in the WCBP. The impactof these loss rates on a lake can be consider-able, as one pound of phosphorous cangenerate up to 300 or more pounds of aquaticplants within the lake basin. Excessive plantand algae growths (the small microscopicplants that can color water green) are gener-ally a primary focus of lake user complaintsand concerns.

B. The lake-watershedconnection

Lakes are simply depressions in the land-scape that are continually filled with waterfrom melting snow or rainfall and groundwa-ter. These depressions were created throughglaciation from the last ice-age.

The water quality of a lake depends largelyon the conditions and dynamics of thewatershed. Every watershed is unique andseveral factors interact to define a lakebasin’s characteristics.

Watershed SizeIn the simplest terms a watershed can bedefined as the area of land that drains into alake or river. One of the very first steps inlake management planning is to understand

the relative size and characteristics of thewatershed. The Minnesota Lake and Water-shed Data Collection Manual providesinformation on watershed delineation.

The following terminology is often usedwhen describing various watershed manage-ment units:

Watershed size rangeMgmt Unit (approx.)

Catchment 0.5 - 1 sq. mi.Sub-watershed 1 - 10 sq. mi.Watershed 10 - 100 sq. mi.Sub-basin 100 - 1,000 sq.mi.Basin 1,000 - 10,000 sq. mi.Most local watershed planning is done at thesub-watershed and watershed level.

Watershed hydrologyThe hydrology of a watershed is defined asthe route the precipitation takes on its way tothe lake. Some precipitation will fall directlyon the lake surface, some will runoff theadjacent land surface into the lake and someinfiltrates into the land surface recharging thegroundwater. As water flows over the surfaceof the land or beneath the ground it can pickup nutrients, minerals and organic matter anddeliver them to the lake where they willinfluence the lake’s characteristics. A basicunderstanding of the watershed’s hydrologyis important to lake management becausemodifications in the watershed, such asfarming, development, draining of wetlandsand the loss of forests can increase how muchand how fast water reaches the lake. In-creases in either the rate or quantity ofsurface water runoff can escalate the trans-port and delivery of sediment and attachednutrients to the lake, and can increase flood-ing and erosion of streambanks along water-courses flowing to the lake.

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capacity. The tannic acid produced by someorganic soils can make the water appearbrown or stained.

A basic understanding of soils helps targetwatershed protection programs to sites thatwill maximize available resources. Forexample, if there are two subwatersheds ofsimilar size, it may be wise to target soilerosion control practices to the one with ahigh percentage of silt and clay, becausethese soils will have a higher potential tonegatively impact the lake.

Landscape FeaturesFeatures on the landscape, both natural andresulting from human activity, greatly influ-ence the characteristics of a lake. Convertingland from its natural vegetation state (prairie,wetlands or forest) to cropland or urban usesalmost always increases surface water runoff.Surface runoff from cropland and urban landoften has nutrients (such as phosphorous) andtoxins (such as pesticides) attached to thesediment. If natural filters such as wetlandsare not present on the landscape, the sedimentand pollutants can be transported to the lake.

The concentration of the nutrients fromfertilizer on cropland or urban land dependson many factors, including the applicationmethod, the time of application in relation torainfall and the solubility of the nutrients.Animal feedlots, pastures and home septicsystems can also add nutrients to the lake.The sediment itself can degrade fish habitatand threaten plantlife.

Lakes that are hydrologically connected toother lakes and large open-water wetlandsoften have unique characteristics that must beacknowledged when developing a lakemanagement plan. For instance, if waterentering a lake has flowed through otherwater bodies, the land use practices and in-lake water chemistry in the upstream lake(s)or wetland(s) will affect the target lake.

Modifications to the natural hydrology, suchas the construction of ditches and stormsewers, can significantly alter the rate andquantity of surface water runoff. If either therate, quantity or quality of surface waterrunoff from a lake’s contributing watershed isdetermined to be a problem, understandingthe watershed hydrology will be the first stepin identifying appropriate goals and objec-tives in the lake management plan.

Many factors influence watershed hydrology,including the physical characteristics de-scribed below—precipitation, soils and theuse of the land. Layers of sand, gravel andclay deposited by glaciers created the ground-water flow patterns that affect lakes. Depend-ing on the patterns and the climate, a lakemay either receive water from or dischargewater into the groundwater system.

PrecipitationThe frequency, intensity and time of year thatrainfall or snowmelt events normally occurwithin a watershed will influence the lake.Precipitation has the ability to detach soilparticles (sediment) and transport them to areceiving water body.

The potential for precipitation to cause soilerosion and to transport pollutants to a lakedepends on the land use, and on rainfall—when, how much and how intense it is.Precipitation is very different, depending onwhere you are in Minnesota. Total precipita-tion varies from a low of 20 inches/year innorthwestern Minnesota to a high of 32inches/year in southeastern Minnesota. Theaverage annual surface runoff is greatest insouthern and southeastern Minnesota and thelowest in northwest and west-central Minne-sota along the border with the Dakotas.Generally, the potential for raindrops toerode soil and transport the sediment andattached pollutants to a lake is greater insouthern and eastern Minnesota than innorthern and western Minnesota.

SoilsUnderstanding soil types found in the water-shed is important, because they influencesurface water runoff, both how much gets tothe lake, and its quality. Soils in Minnesotafall into two broad groups: mineral andorganic. Mineral soils are made up of varyingratios of sand, silt and clay particles. Soilsmade primarily of sand absorb precipitationquickly and are naturally low in availablephosphorus and nitrogen. In contrast, soilsmade of primarily silt and clay generally havelower absorption rates and are generally highin available phosphorus and nitrogen.

Organic soils are made up of more than 50percent organic materials, such as peat.Generally, they are not subject to erosion bywater because of their position in the land-scape (swales) and their high water holding

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C. Lake water qualitymonitoring andassessment

Measuring the lake’s chemical, biological andphysical composition is essential to under-standing how the lake works and to identify-ing appropriate lake management options.Initial measurements will establish parametersthat can characterize the trophic* status andoverall ecology of the lake.

The Minnesota Lake and Watershed DataCollection Manual provides detailed informa-tion on what needs to be collected, along withhow to collect it.

1. Common lake samplingprocedures

A good way to gather lake water quality datais to sample surface water parameters on fiveto 10 occasions from May to September.Collect samples at one or more preselectedmid-lake locations. Lakes with distinct baysneed more sampling sites than round ones.Given the considerable differences in summerweather dry to wet patterns, it will take aminimum of three to five years of datacollection to be able to statistically define“average” conditions.

The parameters most often used to describethe trophic status of a lake are total phospho-rus, Secchi transparency and chlorophyll-a.Since concentrations of total phosphorus andchlorophyll-a are usually expressed in parts-per-billion ranges (µg/L), analytical labs mustbe equipped to accurately measure theseextremely small concentrations.

As land uses vary by ecoregion, so do lakewater quality patterns (table 2). There are

distinct differences in water quality betweenecoregions. Average regional concentrationsof total lake phosphorus vary from 24 µg/L inthe Northern Lakes and Forests ecoregion tomore than 100 µg/L in the Western Corn BeltPlains and the Northern Glaciated Plainsecoregions. Ranges in algae (chlorophyll-a)and transparency followed the same pattern.

2. Common stream samplingprocedures

Since lake water quality depends on thevolume and quality of the waters it receivesfrom its watershed, inflowing streams mustalso be sampled. Usual time periods aresometime in March through November. Thepoint is to gauge stream flows with either astaff gauge, a metal yard stick or a continuousrecording device such as a small computer(these cost about $1,500 to $2,500 perinstallation). Streams are then sampled byhand, called “grab samples,” or by sophisti-cated automated samplers that require profes-sional installation and cost $3,000 or more.

Generally, smaller watersheds need to relymore on automated sampling, becausesurface water runoff tends to peak quicklyand is of very short duration. Typically, atleast 15 total phosphorus measurements perstation per year are needed to reasonablydefine phosphorus concentrations along witha continuous record of daily average flows.Other core parameters needed include totalsuspended solids and total nitrogen. Analyti-cal laboratories must be able to accuratelydetected low concentrations of these param-eters.

Similar to lakes, distinct differences inaverage concentrations have been noted byecoregion for streams. Average regionalconcentrations of total phosphorus varied

* “Trophic status” refers to the nutrients in thelake—what kind and how much.

Table 2: Summer mean lake water quality measures by ecoregion with interquartile in the paren-thesis (i.e., 25th and 75th percentile)

Factor Considered NLF NCHF WCBP NGP

Total Phosphorus (µg/L) 24 (16-33) 60 (35-118) 135 (97-220) 179 (140-404)

Secchi Transparency (feet) 8.9 (5.9-12.8) 4.6 (2.6-7.2) 1.6 (1-3) 2.0 (1-4)

Transparency noted forswimming impaired (feet) < 6.7 < 5.0 < 3.3 < 3.3

Developed by Heiskary and Wilson (1989; 1990)

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from 40 µg/L in the Northern Lakes andForests to more than 240 µg/L in the WesternCorn Belt Plains. There were similar in-creases over the ecoregions for total sus-pended solids and nitrate+nitrite nitrogen aswell as depicted in table 3.

3. Fish community structure as anindicator of water quality

The fish community can also be a reliableindicator of water quality (Schupp andWilson, 1993). Trout have the most criticalrequirements for good water quality. Theyneed well-oxygenated water and prefertemperatures of 50 to 65 degrees Fahrenheit.Oxygen must be present below the ther-mocline in midsummer—a condition usuallyfound only in oligotrophic lakes and occa-sionally in some mesotrophic lakes.

The closely related whitefish and cisco(tullibee) are more widespread than trout andmore tolerant of higher temperatures. Thesetwo species are often found in high numbersin mesotrophic waters (see Carlson TropicStatus Index, Appendix B).

Most members of the sunfish family alsoreach their highest abundance in clear, cleanwaters. Where small- or largemouth bass,rock bass, bluegill and pumpkinseed sunfishare common, the lake is likely to be in goodcondition. Of these, sunfish, smallmouth androck bass are usually associated with thehighest quality.

Two other members of the sunfish family, theblack and white crappie, are more tolerant ofa wide range of conditions. Both reach higherabundances in turbid water than in clearwater. However, the presence of black crap-pies should not be taken as a sign of poorwater quality.

Walleye reach their highest abundance inlarge, mesotrophic lakes. These lakes fre-quently have relatively moderate to low waterclarity, have few rooted aquatic plants andphosphorus that can lead toalgal blooms. Walleyeusually do not do well insmall lakes with clear water,the kind favored by bluegilland largemouth bass.

Northern pike and yellowperch are the most wide-spread species in Minnesota. Northern pikeare generally more abundant in clear waterbecause vision is an important factor forfeeding pike. The highest perch populationsare usually found in mesotrophic waters andare associated withwalleye. Perch are moretolerant of extremes introphic state than thewalleye.

Perhaps the best fishindicators of waterquality are two of thethree bullhead species found in Minnesota:yellow and black bullheads. Yellow bullheadsare found in the highest numbers in lakeswith clear water. In contrast, black bullheadsreach their greatest abundance in very turbid,eutrophic waters. Where both species arepresent, the ratio of black to yellow bullheadscan serve as an additional indicator of waterquality. In moderately eutrophic lakes, blackbullheads outnumber yellow five to one. Aratio of two black bullheads to one yellow isabout normal for a mesotrophic lake and invery clear water yellow bullheads usuallyoutnumber black bullheads. (Appendix Bcontains several graphs that ilustrate theabove information.)

...perhaps the best fishindicators of waterquality are yellow andblack bullheads.

Table 3: Average annual stream quality measures in parts per billion (µg/L) by ecoregion withgeneral middle ranges in the parenthesis (i.e., 25th and 75th percentile)

Factor Considered NLF NCHF WCBP NGP

Total Phosphorus (µg/L) 40 (20-50) 90 (60-150) 240 (160-330) 160 (90-250)

Total Suspended Solids 3,300 8,800 27,000 34,000(1,800-6,000) (4,800-16,000) (10,000-61,000) (11,000-63,000)

Nitrate+Nitrite Nitrogen 30 100 3,900 140 (10-90) (40-260) (1,400-7,400) (10-510)

Developed by McCollor and Heisary (1993)

Trout have the mostcritical requirementsfor good waterquality...

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A. Water qualityThe water quality of a lake is often the focusof citizen concerns because it is directlyrelated to recreation, fisheries, aquaticvegetation and surface water uses. It is often agood place to begin when setting lake man-agement goals and objectives.

The primary agency responsible for managingthe water quality of Minnesota Lakes is theMinnesota Pollution Control Agency. TheMPCA provides:

(1) statewide monitoring and characterizationof quality - diagnostic and problem assess-ments. For example, the statewide lakemonitoring effort works cooperatively withnumerous agencies and hundreds of volun-teers (the Citizens Lake Monitoring and theLake Assessment Programs) to characterizethe water quality of about 2,000 of the state’slakes.

(2) regulatory controls for point and nonpointsources of pollution. Regulation involvescontinual refinement of performance stan-dards for industries, municipalities,individiual sewage treatment systems, feed-lots and other areas to prevent, control orabate water pollution as defined by state andfederal laws.

(3) agreements, grants and loans for preven-tion and control of water pollution sources.Grants and loan programs play in an impor-tant role in improving our water resources.Since 1988, the Clean Water Partnership grantand loan program has awarded $7.34 millionin investigation and remediation grants and$12 million in loan projects (septic tanks,alum treatments etc.) to about 47 differentlake, stream and ground water projects.

(4) technical assistance, education andtechnology transfer for the control of pointand nonpoint sources of pollution. TheMPCA also offers extensive technical assis-tance to local units of government, citizengroups, local steering committees, and otherresource management groups and agenciesranging from the Lake Assessment Programto acid rain and heavy metal pollutionremediation to watershed corrective actions inthe Clean Water Partnership with local unitsand citizen groups. Assistance with the

preparation of lake management plans isprovided from the MPCA’s five regional andSt. Paul offices (see Appendix A for locationsand phone numbers.)

Include water quality goals in thelake management plan.Lake management plans should establishspecific short- and long-term numeric indica-tors of desired water quality. These will beperformance goals against which actual waterquality can be assessed. It is essential tocollect water quality data as directed in theMinnesota Lake Data Collection Manual. Themeasured average summer total phosphorusand Secchi transparency can then be com-pared against “benchmark” in-lake ecoregionvalues, with due consideration by the Techni-cal Committee to factors such as mean depthand water flow-through volumes.

Lake water quality goals are usually aimed ateither protecting the current desired uses orimproving the lake through a combination ofwatershed best management practices and lakeconditions rehabilitation techniques. Protect-ing current uses has often been addressedthrough goals such as “maintainthe lake’s existing water quality,allowing for reasonable year-to-year variabilities caused byclimate.” Such a goal can bereinforced with numeric objec-tives such as an average sum-mer Secchi transparency andthe measured variability. It is normal to seefluctuation of the long-term average transpar-ency of plus or minus 20 percent (for anexample average summer transparency goal of5.5 feet +/- 1.1 feet).

Goals for improving water quality are oftenidentified where there is measured or per-ceived deterioration of water quality. Steeringcommittees may wish to adopt short- andlong-term objectives of for water quality tiedto specific watershed corrective actions. Theapproach is to fix what can be reasonablyfixed and then to monitor in-lake waterquality progress against the benchmarks. (Seeappendix C for water quality benchmarks andphosphorus criteria based on ecoregion.) Ingeneral, reservoirs (lakes with very large

IV. Lake management focus areas

Lake water qualitygoals are usuallyaimed at eitherprotecting the currentdesired uses orimproving the lake.

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rus loading to the lake costing about $3 to$11 per kilogram of reduced phosphorus. Allactions had been implemented by late 1995.

In-lake response to these steps was immedi-ate. Significant as stream nutrient and sedi-ment losses to the lake were reduced by about90 percent. Concurrently measured averagesummer total phosphorus concentrations werenoted to drop from 270 to 89 µg/L by 1994.There was an increase in 1995 to 160 µg/Ldue to internal recycling of P within the lake,which is believed to have been a short-termevent resulting from large changes that haveoccurred in this system. Concurrently, therehas been measured a reduction in the inten-sity and duration of seasonal algal bloomswith all values less than 20 µg/L. Thesetrends are expected to continue as the YellowMedicine River Watershed District and thelocal management groups continue to imple-ment additional watershed actions.

B. FisheriesSportfishing is a vital part of the economyand the overall quality of life enjoyed inMinnesota. Each year, two million anglerstake to the water in pursuit of their favoritespecies. The 1991 National Survey of Fish-ing, Hunting and Wildlife-Associated Recre-ation estimated that sportfishing contributes$846 million to the state’s economy annually(United States Fish and Wildlife Service,1991). Wise management of our aquaticresources is essential to sustaining our richsportfishing heritage and the quality of life inMinnesota.

The best way to protect and improve fishpopulations is to protect and improve fishhabitats.

The primary agency responsible for manag-ing Minnesota’s fish resources is the Minne-sota Department of Natural Resources,Fisheries Section. There are 28 area fisheriesoffices and six regional offices located inoutstate Minnesota (see appendix A forlocations and phone numbers). Area fisheriesmanagers can provide a wealth of informa-tion pertaining to relative fish populationsand historical lake information. Each year theMDNR Fisheries Section conducts 500 - 600fisheries lake surveys. The survey data isused, along with angler input, to prepareformalized fisheries management plans forindividual waters.

watersheds) or shallower lakes (less thanabout 35 feet maximum depth), may beexpected to have greater nutrient concentra-tions and lower transparencies.

Case Study: Lake Shaokatan RestorationProject

Lake Shaokatan is a shallow prairie lake inwest central Lincoln County, Minnesota. Itswater quality deteriorated severely in the1980s due to excessive nutrient loadingassociated with watershed land use practices.Nuisance algal blooms dominated the openwater season and had occasionally producedalgal toxins resulting in the death of dogs andcattle. An extensive data gathering effortbegan in 1991to understand watershednutrient loading and lake response dynamics.

Through the use of seven state-of-the-artstream measurement sites, water and massloading estimates were obtained and lakesystem balances determined. The basicapproach was to manage the lake waterquality by determining and managing the lakenutrient budget to achieve an average in alake total phosphorus goal of 90 µg/L (assuggested by the ecoregion informationsummary in Appendix C).

Lake Shaokatan has a surface area of 1,018acres and a mean depth of 7.3 feet andreceives water from an 8,054-acre watershed.A Clean Water Partnership project begun in1990 found extremely elevated total phospho-rus (average summer value of 270 µg/L).Chlorophyll-a concentrations were episodicwith concentrations noted to exceed 100 µg/Lwith summer means of 20-30 µg/L.

After completion of the monitoring effort, adetailed watershed restoration program wasinitiated in late 1991, consisting of:

a) Diversion of a stream away from a swineoperation;

b) Rehabilitation of the feedlot impactedwetland;

c) Buy out of a swine operation and elimi-nation of this as a nutrient source to thelake;

d) Upgrading of another dairy feedlotoperation;

e) Upgrading of shoreline septic systems;and

f) Rehabilitating four wetland complexes inthe watershed.

These implementation actions resulted inexcess of a 58 percent reduction in phospho-

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Groups that fully implement strategies toimprove water quality will aid fishhabitat protection. Critical shorelines canbe protected or restored through goodlandowner management or public owner-ship. Other activities include aquaticplant restoration, aeration of winterkill-prone lakes, and removal of dams thatlimit fish access to important habitats.

Stocking. When the fisheries managerdetermines that stocking is necessary,groups can help with cost-sharing rearingpond expenses, forage costs or equipmentneeds.

Regulations. Support of regulations toimprove fishing quality is critical to thesuccess of maintaining good fishing.This includes limiting the introduction ofexotic species that may harm fish habitats(see Exotic Species).

Contact the DNR Area Fisheries Manager foran example of a fish management plan.

C. Aquatic VegetationRooted aquatic plants are a natural part ofmost lake communities and provide manybenefits to fish, wildlife and people. They areone of the primary producers in the aquaticfood chain, converting the basic chemicalnutrients in the water and soil into plantmatter that becomes food for other aquaticand terrestrial life.

Aquatic plants have many other importantfunctions, including:

improving water quality by trapping nutri-ents;

protecting shorelines and lake bottoms bydecreasing wave action; and

improving aesthetics by adding to thebiodiversity of the lakeshore.

While aquatic plants perform these importantfunctions, they can also interfere with varioususes of the lake if their growth is profuse.Control of aquatic plants is appropriate whenreasonable access to, and the use of the wateris impeded.

Aquatic plant management is defined as thoseactivities intended to alter an aquatic plantcommunity, either to reduce or increase theabundance of plants in a specified area (e.g.,through harvesting or planting).

Consider fisheries in a lakemanagement plan.The goal of fisheries management is toprotect and restore of fish habitats. The DNRguidelines for preparing a fisheries manage-ment plan include Fisheries ManagementPlanning Guide for Streams and Rivers andthe Lake Management Planning Guide (seereference section). Area fish managers workclosely with individual lake associationswhen developing fish management plans.

First an inventory of the fishery resourcesand aquatic habitats is conducted. Then thefisheries manager, in consultation withestablished groups interested in the manage-ment of the lake (e.g., lake association),develops realistic management goals. Thesegoals are based on the inventory data,historical information and the ecologicalpotential of the lake or stream. Then anoperational plan is developed that identifiesthe actions that will be taken to achieve themanagement goals identified. Actions mayinclude such things as habitat protection andimprovement, stocking, experimental regula-tions or public access development. Finally,the management goals and operations plan

are evaluated to determine ifthey need to be adjusted tobuild upon what has beenlearned. For example, evalua-tion of fish stocking in Minne-sota has provided insight aboutits success in different types of

lakes. Fisheries management is a dynamicprocess that must be continually evaluatedand refined.

Associations, clubs and local units of govern-ment have many avenues to participate infisheries management. Sharing your interestsand concerns with the fisheries manager isimportant in the development of the fisheriesmanagement plan. Consulting with the areafisheries manager will help target the mostimportant fish-related activates to undertake.

Some examples of fish management relatedactivities include:

Inventory. Angler information on fishpopulations can be important in under-standing the status of a population. Forexample, angler diaries can providevaluable information on muskellunge andlargemouth bass populations.

Habitat protection/restoration. This is theprimary area where the long-term healthof fish communities can be ensured.

Fish management plan:✓ Inventory resources✓ Set goals✓ Identify actions✓ Evaluate plan

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Generally, the aquatic vegetation section of alake management plan becomes more impor-tant as the lake’s shoreline becomes heavilydeveloped.

A strategy for lake-wide management ofaquatic plants has been particularly helpfulwhere:

1. Lakes have a large littoral zone withextensive beds of submerged aquaticplants. These lakes usually have a longhistory of extensive aquatic plant controlprojects and lakeshore owners complain that

not enough control is allowed forthem to fully utilize the lake’swater surface.

2. Lakes have stands of bulrush, wild rice,cattail and other emergent vegetation that arein jeopardy of being lost due to shorelinedevelopment. Lakeshore owners, as well asfish and wildlife managers, are concernedwith the loss of these important habitat typesand wish to do something to preserve them.

3. Lakes have floating bog problems.When pieces of bog break loose due tofluctuating water levels or illegal removalactivities, they can destroy property and canbe a hazard to navigation.

The primary agency responsible for manag-ing aquatic plants in Minnesota is the Minne-sota Department of Natural Resources,Division of Fish and Wildlife, Section ofFisheries. Aquatic plants growing in publicwaters below the ordinary high water levelbelong to the state and there are limits placedon the type and amount of control lakeshoreowners can do. Many aquatic plant manage-ment activities require a permit. For example,permits are required for activities that controlemergent vegetation, such as cattails, wildrice or bulrush, or any time aquatic pesticidesare used in public waters. The Section ofFisheries also surveys aquatic plants whenthey prepare fisheries management plans.Contact the Area Fisheries Manager forinformation about a lake’s vegetation or othercharacteristics.

Consider aquatic plant management in alake management plan.

When developing a lake management planthere are several types of aquatic vegetationto consider. Management of each type isdifferent. There are four categories:

Algae have no true roots, stems or leaves,and range in size from tiny, one-celledorganisms to stringy filamentous types.Plankton algae, which consist of freefloating microscopic plants, growthroughout both the littoral zone and thewell-lit surface water of an entire lake.

Submerged plants have stems and leavesthat grow entirely underwater, althoughsome may also have floating leaves.Flowers and seeds on short stems thatextend above the water may also bepresent. Submerged plants grow nearshores to the deepest part of the littoralzone and display a wide range of plantshapes. Depending on the species, theymay form a low-growing “meadow” nearthe lake bottom, grow with lots of openspace between plant stems, or form densestands or surface mats.

Floating-leaf plants are often rooted in thelake bottom, but their leaves and flowersfloat on the water surface. Water lilies area well-known example. Floating leafplants typically grow in protected areaswhere there is little wave action.

Emergent plants are rooted in the lakebottom, but their leaves and stems extendout of the water. Cattails, bulrushes andother emergent plants typically grow inwetlands and along the shore where thewater is less than 4 feet deep.

In many cases a small amount of control toallow access by individual landowners is allthat is required to deal with aquatic vegeta-tion issues. However, when issues becomemore complex and involve many, if not all,property owners, then it is time to develop anaquatic vegetation section for the lakemanagement plan.

To develop an aquatic plant managementsection for a lake management plan, contactthe MDNR area fisheries office. The fisheriesmanager or aquatic plant specialist will workcooperatively with representatives of otheragencies (e.g., MPCA, SWCD), lakeshoreowners and other concerned groups from thecommunity to develop this section. Many ofthese representatives will have valuableinformation about the lake, including the

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amount and types of vegetation present,fisheries, bottom types, shoreline develop-ment, water clarity and other information thatmay help to identify trends or changes in thelake environment. The fisheries manager willalso be able to identify important habitat andother sensitive areas in the lake. Including anaquatic vegetation section in the lake man-agement plan provides an opportunity toprotect the future health of the lake as well asallow for multiple recreational uses.

Case study; Big Birch LakeBig Birch Lake in Todd County is a goodexample of how a Lake Vegetation Manage-ment Plan (LVMP) can be used to addresslake management issues. Big Birch is highlydeveloped. The northwest shoreline and anarea called Hunter’s Bay have a band ofcattails 100 to 300 feet wide and bulrushesextending into the deeper water. Members ofthe lake association were concerned that thecattails and bulrush were being illegallydestroyed as these areas were being devel-oped. The lake association met with theaquatic plant specialist and cooperativelydeveloped an LVMP that will help protectaquatic vegetation and the lake environment.The lake association is using the plan andinformation from the DNR to educate othershoreline property owners about the value ofaquatic vegetation and the appropriate waysto obtain access to the lake.

D. WildlifeMinnesota’s lakes are home to many speciesof wildlife. From our famous loons and baldeagles to muskrats, otters and frogs, wildlifeis an important part of our relationship withlakes. In fact, Minnesota’s abundant wildlifecan be attributed largely to our wealth ofsurface water. From small marshes to largelakes, these waters are essential to the sur-vival of wildlife.

The most important wildlife habitat begins atthe shoreline. The more natural the shoreline,with trees, shrubs and herbaceous vegetation,the more likely that wildlife will be there.Just as important is the shallow water zoneclose to shore. Cattail, bulrush and wild ricealong the shoreline provide both feeding andnesting areas for wildlife. Loons, black ternsand red-necked grebes are important Minne-sota birds that are particularly affected bydestruction of this vegetation. Underwatervegetation is also important to wildlife formany portions of their life cycle, includingbreeding and rearing of their young.

The primary agency charged with the man-agement of Minnesota’s wildlife is theDepartment of Natural Resources, Divisionof Fish and Wildlife, Wildlife Section.DNR Area Wildlife Managers and RegionalNongame Wildlife Specialists are locatedacross the state. (Please refer to Appendix Afor the location and telephone number ofregional and area offices.)

Incorporate wildlife in a lakemanagement plan.Lake management plans are a valuable toolfor considering the future of the wildliferesources in and around your lake and itswatershed. The DNR can provide advice onhow to identify and inventory the existingwildlife. This inventory of wildlife, and thehabitat areas they use, will help set lakemanagement goals that protect and enhancethis important resource. Wildlife populationgoals are best achieved by creating andprotecting critical habitat areas on your lake.

Wildlife will also benefit from efforts toimprove the lake’s watershed. Like the lakeitself, wildlife considerations extend beyondthe water’s edge. Aquatic wildlife often spendpart of their time in streams, wetlands andupland areas some distance from the lake. Inmany cases, the availability of this habitat iscritical to their survival. The buffer areasalong the edges of inlet streams and upstreamlakes and wetlands provide travel corridorsfor wildlife. These corridors are particularlyimportant for song birds, frogs and turtles.Protection and restoration of wetlands iscritical to both fish and wildlife as well as toimproving the quality of water flowing intothe lake.

Shallow lakes occurring in the watershed areimportant wildlife areas and are often spawn-ing areas for fish. These lakes suffer from thesame factors as the downstream lakes theycontribute to. The restoration and protectionof aquatic vegetation in these areas is key toimproving their quality and the quality of therunoff that ends up downstream. The DNRWildlife Section will help to evaluate theseshallow lakes and recommend managementideas. These lakes can even be designated aswildlife management lakes through a publichearing process if conditions warrant.

Some examples of actions to accomplishwildlife goals and objectives in the lakemanagement plan include:

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this area by working through the Reinvest inMinnesota Critical Habitat program withmatching funds. As a state-owned AquaticManagement area, the shoreline will bemanaged by DNR- Fisheries. The lake asso-ciation has continued its efforts by workingwith the DNR Nongame Wildlife Specialist toerect nesting platforms for ospreys and loons,as well as nesting boxes for wood ducks,goldeneyes, and hooded mergansers.

E. Exotic SpeciesFor the purposes of this manual, the term“exotic species” means a plant or animal notnative to Minnesota, or one that was intro-duced to Minnesota after 1800.

Many aquatic exotic species present in Minne-sota are the result of intentional introductions.The brown trout, rainbow trout and chinooksalmon were introduced to provide a uniquefishing experience to Minnesota anglers.Although there is some debate, the introduc-tion of these species is generally perceived asbeneficial. The common carp, another intro-duced species, was originally thought to be aboon for anglers because it could toleratedegraded habitat conditions, grew rapidly andwas easy to catch. The carp, established inmost of the major watersheds of NorthAmerica, is now often considered a pest, andis blamed for degradation of habitat inmarshes, lakes and streams.

Harmful exotic species may also be introducedunintentionally into Minnesota’s lakes andrivers. For example, the spiny water flea,zebra mussel, ruffe and white perch were allprobably introduced into the Great Lakes fromballast water discharged from ships travellingfrom European ports. Eurasian watermilfoil,an exotic water plant, has spread from coast tocoast on boats, trailers, bait buckets andperhaps even by waterfowl. How this aquaticplant arrived in the U.S. is uncertain.

Establishing no wake zones or seasonalsanctuaries will help to control distur-bances to nesting wildlife in criticalareas.

Adding artificial nesting structures forloons, and houses for other species willhelp to preserve the lake’s wildliferesource.

Work to preserve areas by entering intolandowner agreements or conservationeasements with landowners in the water-shed.

Explore the possibility of helping the stateacquire land for Aquatic ManagementAreas or Wildlife Management Areas.

Contact the DNR Area Wildlife Manager foractions tailored to the local resources.

Case study: Big Sugar Bush Lake,Kabekona Lake

The peninsula on Big Sugar Bush Lake inBecker County was popular with lakeshoreowners who enjoyed the wildlife using thearea. Its 18 acres of maple, basswood andaspen were interspersed with a number ofcentury-old white pines. The Big Sugar BushLake Association purchased the area anddonated it to the DNR as a wildlife manage-ment area. The donation not only protects thisundeveloped lakeshore for osprey, woodducks, loons and other wildlife, but wasmatched with the Reinvest in MinnesotaCritical Habitat program to provide funds tohelp protect other areas. The lake associationis currently working with the DNR NongameWildlife Specialist to establish a wildlifeinterpretive project on the peninsula.

On the north shore of Kabekona Lake inHubbard County are 3 acres of naturalshoreline near a bald eagle nest. Bulrushes inthe shallow water provide both fish andwildlife habitat, while behind an ice ridge,the tamarack, spruce, ash and dogwoodprovide warblers and other songbirds withnesting and feeding areas. The KabekonaLake Association has ensured protection of

purpleloosestrife

ruffe

flowering rush

spiny water flea

curly-leaf pondweed

zebra mussel

round goby

Eurasianwatermilfoil

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Introducing species accidentally or intention-ally from one habit to another is risky busi-ness. Freed from the predators, parasites,pathogens and competitors that keep theirnumbers in check, species introduced intonew habitats often overrun their new homeand crowd out native species. In the presenceof enough food and a favorable environment,their numbers will increase rapidly. Onceestablished, exotics are rarely eliminated.

Exotic species have the potential to causeseveral problems. They can reduce theabundance of native species by out-competingthem for food or space. Wildlife that dependson native species for food, cover and nestingsites may be faced with habitat of lower, if notunacceptable, quality. Initially, the impact ofexotic species on native plant and animalcommunities are unclear; it may take years forit to become fully apparent. Exotic speciesalso affect recreation and economic activities.

The primary agency responsible for managingexotic aquatic species in Minnesota is theMinnesota Department of Natural Re-sources, Division of Fish and Wildlife,which manages the Harmful Exotic SpeciesManagement Program. They can provideinformation on exotic species, and theirecology, biology, and on the location ofexisting populations in Minnesota. They alsohave information on current exotic specieslaws and rules and on control of species suchas purple loosestrife and Eurasianwatermilfoil. Much of this information issummarized in the Exotic Species Handbooklisted in the reference section of this manual.

Consider exotic species in a lakemanagement plan.

The first step in designing exotic speciescontrol for a lake management plan is tocomplete an assessment of the current level ofinfestation. Depending on the phase ofinfestation in a particular lake, there areseveral actions that can be identified in thelake management plan:

Phase I - No known infestations of exoticspecies. When no harmful exotic species havebeen observed, the focus of the exoticscomponent of a lake management plan shouldbe education aimed at prevention. Thisincludes training on the identification ofexotic species, the risks involved in theirintroduction and how to prevent their spread.Regular monitoring to identify an exoticintroduction is also recommended

Phase II - Intensive Management. Considerthese management strategies where a newexotic species has been recently identifiedand the possibility of containing or eliminat-ing the population still exists. In this situa-tion, the lake management plan would likelyidentify three actions:

1. Implement control measures in coordina-tion with the DNR;

2. Keep lake residents and users informedof the changing situation and specialregulations that may apply; and

3. Monitor the effectiveness of controlefforts in coordination with the DNR.

Phase III - Maintenance management. Ifharmful exotic species are already wellestablished, outline strategies to reduce therecreational, economic or ecological magni-tude of their impacts in the lake managementplan. These efforts will often be concentratedwhere exotics cause the most problems,interfere with the lake use, or can be easilyspread. The DNR’s Harmful Exotic SpeciesManagement Program can provide assistancewith these management activities.

Case study: Bay LakeBay Lake in Crow Wing county is a goodexample of how exotic species managementcan be implemented cooperatively by localand state interests. In the fall of 1992, alakeshore resident spotted a suspectedEurasian watermilfoil plant and contacted theDNR Regional office in Brainerd. A DNRaquatic plant management specialist in-spected the site, and within one week theplant was positively identified as Eurasianwatermilfoil. It was confined to a smallportion of the lake, which was treated withherbicide. In 1993, the lake was inspectedseveral times by the aquatic plant manage-ment specialist and the lake association; onlyone Eurasian watermilfoil was found, and itwas removed. In 1994, milfoil was found onseveral sites, and during 1995 spread to about10 sites occupying nearly 100 acres, most ofwhich were treated with hericide. The DNRtrained the lake association in aquatic plantidentification and survey techniques, and theassociation organized their own lake monitor-ing program. Association members were alsotrained on how to conduct public awarenessevents at the public access to prevent furtherintroductions of exotic species.

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F. Land Use and Zoning

The amenities associated with living on alake, including many recreational opportuni-ties and aesthetic rewards, place lakeshoreproperty in high demand for home sites andcertain commercial businesses such as resortsand marinas. However, not all lands sur-rounding a lake may be suited for suchdevelopment. Proper planning is essential toensure that development will occur in a safeand orderly fashion, and with minimal impacton the lake.

The state Shoreland Management Act estab-lishes a set of minimum development stan-dards specifically for shoreland areas.Shorelands are defined as lands locatedwithin 1,000 feet of a lake, pond or flowage,and within 300 feet of a river. Shorelandstandards are adopted and administered bylocal governments and are commonly incor-porated into their overall zoning controls.Like zoning controls, shoreland standards setpermissible uses and specify minimumrequirements for newly created lots.Shoreland standards may also limit physicalalterations to shoreland property, and maycontrol the placement of structures, roads andother improvements to minimize impacts onthe adjoining lake.

The primary agency responsible for land usecontrols and zoning in Minnesota is localunits of government such as counties,municipalities or townships. They have theauthority to administer land use zoningcontrols for areas within their boundaries.Local zoning controls generally apply to alllands in the government unit’s jurisdiction,including lakeshore. These controls mayidentify a list of uses that are permissible ornon-permissible for given areas or “zones.”They also may specify minimum designstandards for newly created lots, onsite sewersystems and wells, subdivision plats, plannedunit developments and for construction ingeneral.

Most local governments also administerregulations pertaining to the use of floodplainareas. Floodplain regulations specify mini-mum elevation requirements for structuresand access roads and limit certain types ofuses in floodplain areas. Such controls areparticularly important on lakes with largewatersheds, or lakes which exhibit extremewater level fluctuations. Generally, if a localgovernment is administering floodplainregulations, then floodplain areas along somelakes and rivers have been mapped. Copies ofFlood Insurance Rate Maps are available

from the county or municipal zoning officesor the DNR Area Hydrologist.

Consider land use controls and zoningregulations in a lake management plan.

Since local governments have the legalauthority to adopt land use regulations, theplanning process begins with a contact to thelocal planning and zoning administrator. Thelake management planning group, with thehelp of the administrator,should use the list of planningconsiderations to determine thebest suited uses for a particularzone or district (e.g., planneddevelopment vs. open space forwildlife).

Before designing a set of landuse controls for a lake it is important toinventory the landscape features that influ-ence the lake’s water quality and its ability tosustain fish and wildlife. While shorelandstandards generally apply only to landswithin 1,000 feet of a lake, planners mightwant to consider the entire watershed of thelake in their planning efforts since activitiesanywhere within the watershed have thepotential to impact the lake. Some of theresources that should be inventoried include:

Wetlands. Wetlands serve as filters toremove nutrients and sediments from surfacerunoff before they reach the lake. They alsoprovide important habitat for many species ofwildlife. Wetland vegetation along alakeshore provides habitat for fish andwildlife and protects the shore from erosioncaused by wave action. Wetlands are alsoprotected by various federal, state or locallaws. Wetlands have been mapped on a seriesof National Wetland Inventory Maps. Thesemaps may be viewed at the local NaturalResources Conservation Service office or atthe soil and water conservation district office.

Bluffs and steep slopes. Lands characterizedby bluffs and steep slopes can become aserious erosion threat if they are disturbed bygrading, filling or vegetation removal. Bluffsare already protected from intensive removalof vegetation and grading or filling involvingmore than 10 cubic yards of material by localshoreland management ordinances. Bluffsrise at least 25 feet above the lake at anaverage slope of 30 percent or greater andcan generally be identified from topographicmaps the U.S. Geological Survey (USGS)Quadrangle Maps. Such maps can be ob-

Shoreland standardsare adopted andadministered by localgovernments and arecommonly incorpo-rated into their overallzoning controls.

22

public accesses, parks, marinas, highwaysadjacent to lakes, private septic systems andmunicipal sewage discharges and float-planeairports.

The inventory can be used to determine thebest uses for individual tracts of shoreland orother critical areas identified. A set of writtenstandards can be developed to guide futureuse of these lands. Generally, this entails thedesignation of land use districts or zonesaround the lake and the preparation of a listof permissible, conditional and prohibiteduses for each district. The districts must beshown on the zoning maps of the localgovernment and district boundaries must bedefinable to a specific feature (e.g., propertyline, highways, government lot line, etc.).

For each district or zone, it is necessary todevelop a specific list of performance stan-dards. These will establish minimum guide-lines for development and may include suchthings as minimum lot sizes and building andsewage system setbacks from the lake. Whenthe intended uses for the land have beendetermined and the performance standardsdefined, these documents are presented indraft at a public hearing conducted by thelocal planning commission or board todetermine if there is any need to add, amendor eliminate portions of the plan. After theplan has cleared the hearing process, itbecomes part of the zoning ordinance and hasthe force and effect of law.

Possible sources of funding for land useplanning activities may include the localgovernment or the soil and water conserva-tion district. Active lake associations mayalso have an operating budget to fund certainaspects of the process

The shoreland management program’s goal isfor each newly created lot in shorelands to besuited in its natural state for the intended use.If that use is for development of a homesite,then each lot should have enough land that isfree of limiting factors such as wetlands andbluffs to accommodate the placement of allproposed structures, an onsite water supplywell and sewage disposal system and a sitefor future replacement of the sewage system.In addition, the property should be accessibleby road. The presence of bluffs, wetlands orother surface water features may restrict theability to extend roadways into certain areas.

G. Managing water

tained from the USGS or may be viewed atCounty or Municipal offices (Zoning or LandDepartment) or at local offices of the DNR.

Shallow groundwater or bedrock. Thepresence of the groundwater table or bedrockat or near the soil surface limits certainconstruction activities, particularly onsitesewage disposal systems.

Soils. Some soils have poor drainage orstability characteristics that affect their abilityto support development of roads, buildings oronsite sewage disposal systems. In mostMinnesota counties, soils have been mappedas part of the County Soil Survey. Thesesurveys classify the soil types and explain thelimitations of each type for developmentpurposes. They also provide information onseasonal high groundwater levels and shallowbedrock. They surveys are available from thecounty soil and water conservation districtoffice or the USDA Natural ResourcesConservation Service.

Important habitat areas. Areas that supporthigh quality fish or wildlife habitat or rareplants and animals generally need bufferareas surrounding them where disturbanceswill be minimized. Therefore, the locations ofsuch areas should be determined and theirprotection should be reflected in land useplans. Information on these resources can beobtained from the MDNR Area Fisheries andWildlife Manager.

Cultural and historic sites. These includesites of known archeological significance,unplatted cemeteries and historic structures.Shoreland areas are generally more likely tohave sites of historic cultural significancethan non-shoreland areas. Information onknown sites or the potential for such sites toexist in an area can be obtained from theMinnesota Historical Society or the office ofthe State Archeologist.

Additional areas that should be consideredwhen examining land use in a watershed are:

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surface use conflictsThe goal of lake management is to ensurethat the lake can continue to provide thebenefits that attract homeowners and users.However, conflicts among uses arise almostinvariably. Successful resolution of conflictslies in the ability of the users to workcollaboratively to arrive at acceptable com-promises.

The primary agency responsible for manag-ing surface water use conflicts is the Minne-sota Department of Natural Resources,Bureau of Information and Education.The Boat & Water Safety Section withinthe Bureau oversees surface water use and isin charge of administering the Water SurfaceUse Management (WSUM) program. Thegoal of this program is to enhance therecreation use, safety and enjoyment of thewater surfaces in Minnesota and to preservethese water resources in a way that reflectsthe state’s concern for the protection of itsnatural resources.

Consider surface use management in alake management plan.

Any governmental unit may formulate,amend or delete controls for water surfaceuse by adopting an ordinance. Submit theordinance for approval by the MDNR Boatand Water Safety Coordinator 1-800-766-6000, or in the metro area 296-3336.

The ordinance must:

✓ where practical and feasible, accommodateall compatible recreational uses;

✓ minimize adverse impacts on naturalresources;

✓ minimize conflicts between users in a waythat provides for maximum use, safety andenjoyment; and

✓ conform to the standards set in WSUMRules.

The WSUM rules establish standards topromote uniformity of ordinances or rules onthe use of watercraft throughout the state. Inaddition, they encourage compliance andease of enforcement. It is not required that allthe WSUM standards be included in theordinance, only those necessary to reduce theconflict. The governmental unit may selectfrom the following standards:

Watercraft type and size. Controls may beformulated for the type and/or size of water-craft permissible for use on the surface of thewater body or portion of the water body.

Motor type and size. Controls on the maxi-mum total horsepower of motor(s) poweringwatercraft will utilize one or more of thefollowing options: 25 hp; 10hp; electricmotors; no motors.

Direction of travel. Directional controls, ifused, will mandate watercraft to follow acounterclockwise direction of travel.

Speed Limits. Controls concerning themaximum watercraft will utilize one or moreof the following miles-per-hour cutoffs: slowno wake, 15 mph or 40 mph.

Effective time. Controls must use one ormore of the four time periods specified in therules.

Area zoning. Controls will clearly specifywhich portion of the water body is affectedby the control.

The formal review process begins when thelocal unit of government submits the follow-ing information to the DNR Bureau ofInformation and Education for review andapproval, prior to adopting an ordinance asrequired by the rules:

✓ water surface worksheet with a map of thelake highlighting the areas to be regulated;

✓ a statement evaluating whether the infor-mation reveals significant conflicts andexplains why the particular proposedcontrols were selected (i.e., provideadequate justification for the adoption ofthe controls);

✓ the proposed ordinance; and

✓ description of the public hearing heldconcerning the proposed controls, includ-ing an account of the statement of eachperson who testified.

If more than one governmental unit is in-volved in adopting the ordinance, all thegovernmental units with jurisdiction over theparticular water body must agree with theordinance and develop a joint powers agree-ment. If for some reason the DNR denies theproposed ordinance, the denial will be in theform of a letter which will explain thereasons for denial. The governmental unitmay amend the proposed ordinance andresubmit the proposed ordinance for a secondreview by the MDNR.

24

The DNR will notify the governmental unitin writing of approval or denial within 120days after receiving all of the above informa-tion. Failure of the DNR to notify the govern-mental unit will be considered approval. Thegovernmental unit adopting an ordinancemust provide for notification of the ordinanceto the public, which involves placing signs atpublic watercraft launch sites outliningessential elements of the ordinance.

H. Public water accessResearch has shown that Minnesotans relyheavily upon public access sites to accesslakes and rivers. A 1988 boater surveyconducted by the University of Minnesotashowed that three-fourths of the state’s boatowners launch a boat at a public water accesssite at least once a year. In addition, over 80percent of boat owners report using publicwater access sites for recreation activitiesother than boating.

The primary agency responsible for publicwater accesses in Minnesota is the Minne-sota Department of Natural ResourcesTrails and Waterways Unit. They areresponsible for the acquisition, developmentand management of public water access sites.The DNR either manages them as individualunits or enters into cooperative agreementswith county, state and federal agencies, aswell as local units of government such astownships and municipalities.

The DNR’s efforts to establish and managepublic water access sites are guided byMinnesota Statutes and established written

DNR policy. The goal of the public wateraccess program is free and adequate publicaccess to all of Minnesota’s lake and riverresources consistent with recreational de-mand and resource capabilities to providerecreation opportunities.

Consider public access sites in a lakemanagement plan.

The DNR is also on the alert for propertiesthat are being sold that may be used as a boataccess. Site usability is based upon a set ofcriteria designed by the DNR. The pricing isbased upon fair market value. When develop-ing a lake management plan, it would be wiseto identify sites that may be suitable for apublic access.

If a desirable site is identified, construction isusually performed by a local contractoraccording to DNR specifications. There areseveral criteria that the public access mustmeet to be approved by the DNR. Contact thelocal DNR Trails and Waterways office in St.Paul for more information on the constructionand design of public accesses.

The DNR routinely works with interestedparties in the design of access sites from theinitial concept stage through final design.This cooperative process does not end withthe construction of the access site. After theaccess is developed, the Trails and Water-ways Unit will continue to work with thecommunity and neighbors on issues regardingmaintenance and operation procedures.

Lakes are a very important part of Minneso-tans’ well being and economic diversity. One

25

of the state’s most important products is the“water experience” and it directly influencesproperty values, recreation, tourism andrelated activities. As in any product, quality isimportant and Minnesota competes forlimited discretionary dollars with Wisconsin,Michigan and Canada. People will go else-where if our product is not competitive.

The quality of our lake resources is thecumulative result of the people and theiractivities within the lake’s drainage basin.And, with ever increasing pressures upon ourlakes, they cannot be expected to assimilateall impacts forever. The need to manage lakesas a limited resource requiring purposefulplanning and action is real and immediate.Lake management requires the collectiveresources of citizens, local, county and stategovernments and commercial enterprise.Neglect often results in negative impacts,water quality declines, lost fisheries andultimately lost revenues and a degradedquality of life. Lake rehabilitation is a verycostly venture with an uncertain outcome.

Citizen-initiated steering committeeshavebeen an effective method for developing

specific lake and watershed managementplans. These efforts may be expected torequire a year or more to prepare and up toseveral subsequent years to enact changes inthe daily lives of watershed residents. Coop-eration, collaboration and a willingness tochange are the prime ingredients of thesuccessful ventures. Finger pointing andrecrimination will quickly ruin the best ofintentions.

Formalized lake plans should be acknowl-edged by and incorporated into county,township, watershed district or other units ofgovernment operations—particularly those ofthe planning and zoning departments. Chip-ping away at the problems does work andeveryone can do something, no matter howsmall the efforts may seem. It all adds up andmakes a difference over time!

VI. References

V. Conclusion

26

Lake Management - General

Data Information Committee, Lakes Task Force and the Environmental Quality Board. 1994

Minnesota Lake and Watershed Data Collection Manual. Available through the Minne-

sota Lakes Association, 1-800-515-5253. $10 + 3 shipping.

Dresen, M. D. and Korth, R.M. 1994. Life on the Edge... Owning Waterfront Property.

University of Wisconsin College of Natural Resources. (715) 346-2116. $3.

Freshwater Foundation and Minnesota Pollution Control Agency. 1985. A Citizens Guide to

Lake Protection. Available through the MPCA (612) 296-6300 or Freshwater Foundation

(612) 471-8407. Free.

Heiskary, S. A. and C. B. Wilson. 1989. The regional nature of lake water quality across

Minnesota: an analysis for improving resource management. MN Jour. Acad. Sci.:55(1)

71-77. Available through the MPCA Water Quality Division. (612) 296-7202.

McComas, Steve. 1993. Lakesmarts: The first lake maintenance handbook. Terrene

Institute. Available through Blue Water Science, 550 S. Snelling Ave., Saint Paul, MN

55116, (612) 690-9602. Price $18.95, major credit cards accepted.

New York State Department of Environmental Conservation. 1990. Diet for a Small Lake: A

New Yorker’s Guide to Lake Management. Federation of Lake Associations, Inc. Roches-

ter, New York.

U.S. EPA. 1988. Lake and Reservoir Restoration Guidance Manual. First ed. EPA 440/5-

88-002. (202) 382-2090. Free.

U.S. EPA. 1990. Monitoring Lake and Reservoir Restoration. Technical Supplement to

the Lake and Reservoir Restoration Guidance Manual. EPA 440/4-90-007. (202) 382-

2090. Free.

Watershed Management - Land Treatment

Arrowhead Water Quality Team. 1996. Video: “Keeping Our Shores” and “Protecting

Minnesota Waters” fact sheets (18). Lake County SWCD, Box 14, Two Harbors, MN

55616 (218) 834-6638. $20 + tax.

Arrowhead Water Quality Team. 1996. Protecting Minnesota Waters: Shoreland Best

Management Practices. Minnesota Extension Service, Duluth (218) 726-7512.

Conservation Technology Information Center (CTIC). Six-pamphlet series compiled as part

of the Know Your Watershed Campaign:

Getting to Know Your Watershed; Managing Conflict; Building Local Partnerships; Putting

Together a Watershed Management Plan; Leading and Communicating; Reflecting on

Lakes. Available through the CTIC at 1220 Potter Drive, Room 170, West Lafayette, IN

47906 (317) 494-9555. $2 per pamphlet.

Conservation Technology Information Center. 1994-5. Nonpoint Source Water Quality Con-

tacts. (317) 494-9555.

Minnesota Pollution Control Agency. 1991. Agriculture and Water Quality: Best Manage-

ment Practices for Minnesota. Available through the MPCA Water Quality Division (612)

27


296-7202. Free.

Minnesota Pollution Control Agency. 1988. Protecting Minnesota’s Waters . . . The Land-

Use Connection. Available through the MPCA (612) 296-6300. Free.

Tip of the Mitt Watershed Council. 1995. Understanding, Living with and Controlling

Shoreline Erosion: a Guidebook for Shoreline Property Owners. Conway, Michigan

(616) 347-1181. Shipping/handling fee approx. $3.

Fisheries

Minnesota Department of Natural Resources. 1982. Lake Management Planning Guide.

MDNR Division of Fish and Wildlife, Section of Fisheries, Special Publication 131, Saint

Paul, MN (612) 296-3325. Free.

Minnesota Department of Natural Resources. 1993. Manual of Instructions for Lake Survey.

MDNR Division of Fish and Wildlife, Section of Fisheries, Special Publication 147, Saint

Paul, MN (612) 296-3325. Free.

Minnesota Department of Natural Resources. 1993. Fisheries Management Planning Guide

for Streams and Rivers. MDNR Division of Fish and Wildlife, Section of Fisheries,

Special Publication 148, Saint Paul, MN (612) 296-3325. Free.

Schupp, D. H. 1992. An Ecological Classification of Minnesota Lakes with Associated Fish

Communities. MDNR Division of Fish and Wildlife, Section of Fisheries, Investigational

Report 417, Saint Paul, MN (612) 296-3325. Free.

U.S. EPA. 1993. Fish and Fisheries Management in Lakes and Reservoirs. Technical

Supplement to the Lake and Reservoir Restoration Guidance Manual. EPA 841-R-93-

002. (202) 382-2090. Free.

U.S. Department of the Interior and U.S. Department of Commerce. 1993. 1991 National

Survey of Fishing, Hunting and Wildlife-Associated Recreation (Minnesota). U.S.

Government Printing Office, Washington D.C. Free.

Aquatic Vegetation

Minnesota Department of Natural Resources. 1994. A Guide to Aquatic Plants. MDNR

Division of Fish and Wildlife. Ecological Services Section, 500 Lafayette Road, Saint Paul,

MN 55155-4025 (612)296-2835 Metro Area; 1-800-766-6000 Toll-Free in Minnesota. Free.

Exotic Species

Minnesota Department of Natural Resources. Exotic Species Handbook. MDNR Division of

Fish and Wildlife, Ecological Services Section, 500 Lafayette Road, Saint Paul, MN 55155-

4025 (612) 296-2835 Metro Area; 1-800-766-6000 Toll-Free in Minnesota.

Other

Minnesota Department of Natural Resources, 1995. A User’s Guide to the Minnesota Natural

Heritage Information System. Minnesota Natural Heritage and Nongame Wildlife Pro-

grams, 500 Lafayette Road, Saint Paul, MN 55155-4025 (612) 296-8279 or 296-8319. Free.

28

Appendices

Appendix A – Water quality indicesCarlson Trophic Index

Fish Community Structure Graphs

Appendix B – Lake water quality benchmarks based on ecoregion

CARLSON'S TROPHIC STATE INDEX VALUESTSI Relationships based on mean summer data for 1991.

Changes in the Biological Condition of Lakes With Changes in Trophic State

R.E. Carlson

TSI < 30 Classical oligotrophy: Clear water, oxygen throughout the year in hypolimnion,salmonid fisheries in deep lakes.

TSI 30 - 40 Deeper lakes still exhibit classical oligotrophy, but some shallower lakes willbecome anoxic in the hypolimnion during the summer.

TSI 40 - 50 Water moderately clear, but increasing probability of anoxia in hypolimnion duringsummer.

TSI 50 - 60 Lower boundary of classical eutrophy: Decreased transparency, anoxic hypolimniaduring the summer, macrophyte problems evident, warm-water fisheries only.

TSI 60 - 70 Dominance of blue-green algae, algal scums probable, extensive macrophyteproblems.

TSI 70 - 80 Heavy algal blooms possible throughout the summer, dense macrophyte beds, butextent limited by light penetration. Often would be classified as hypertrophic..

TSI > 80 Algal scums, summer fish kills, few macrophytes, dominance of rough fish.

Water quality benchmarks based on ecoregion

Ecoregion Reference Lakes - One means for placing lake water quality information in perspective is tocompare summer mean values to those found in reference lakes from the same ecoregion in which the lake islocated in. Ecoregions were mapped for the United States from information on soils, landform, potentialnatural vegetation, -and land use by the U.S. Environmental Protection Agency. For Minnesota, within-regionsimilarities in terms of quality and lake morphometric characteristics have been noted. Reference lakes,deemed to be representative and minimally impacted by man (e.g., no point source wastewater discharges, nolarge urban areas in the watershed, etc.) were sampled in each ecoregion by the MPCA from 1985 through1988. The reference lake data base consists of approximately 90 lakes distributed as follows among the fourecoregions with the majority of Minnesota's lakes: Northern Lakes and Forests - 30, North Central HardwoodForest - 38, Western Corn Belt Plains - 12, and Northern Glaciated Plains - 10. Data from the reference lakescan be used as a "yardstick" to compare other data against. Table I provides a range of summer mean valuesfor each parameter and each ecoregion. These values were taken from the "inter-quartile range" (25th to 75thpercentile) of the reference lakes for each region. By using these values, we have excluded the very lowvalues (lower 25 percent) and the very high values (upper 25 percent) and thus, have a range of values whichrepresent the central tendency of the reference lake's water quality. If your lake is near the transition zone oftwo ecoregions is often useful to make comparisons to reference lakes from both ecoregions.

Fish Community Structure Graphs

Relative fishery abundance (vertical axis) versuslake water quality TSI (horizontal axis)

Minnesota Lake Phosphorus Criteria Development- Because of regional diversity in lake and watershedcharacteristics, it was unlikely that a single total phosphorus value could be adopted as a statewide criterionfor lake protection in Minnesota (Heiskary et al. 1987). Rather, a methodology was needed for developinglake water quality criteria on a regional or lake-specific basis.

The methodology for establishing lake water quality criteria in Minnesota considered the following (fromHeiskary and Walker, 1988):

1. phosphorus impacts on lake condition (as measured by chlorophyll a, bloom frequency, transparency,and hypolimnetic oxygen depletion;

2. impacts on lake user (aesthetics, recreation, fisheries, water supply, etc.); and

3. attainability (as related to watershed characteristics, regional phosphorus export values, lakemorphometry, etc.).

Previous papers (Heiskary et al. 1987) have described the range in the trophic status of lakes in Minnesotaand the utility of the ecoregion framework in explaining some of this variability. Ecoregion maps, asdeveloped by EPA ERL-Corvallis, are based on land use, soils, land form, and potential natural vegetation(Omernik, 1987). Recognizing patterns in lake trophic status between these regions has permitted thedevelopment of some generalized lake management strategies (Heiskary and Wilson, 1988).

Minnesota is characterized by seven ecoregions (Figure 1). However, over 98 percent of Minnesota's lakesare found in four of the state's seven ecoregions (Heiskary et al. 1987). Typical land use varies from theforests in the north to the primary cultivated land and pastures to the south. A more detailed presentation ofthe information may be found in Heiskary and Wilson (1988 and 1990).

The ecoregion framework provides a regional perspective on the uses of lakes in each part of the state andallows for the definition of "most sensitive uses" in each region. The MPCA has defined the "most sensitiveuse" of a lake as that use (or uses) which can be affected or even lost as a result of an increase in the trophicstatus of the lake. Two examples include drinking water supplies and cold water fisheries. In the case ofdrinking water supplies, eutrophication can increase water treatment costs (Walker, 1985), contribute to tasteand odor problems (Walker, 1985), and increase production of trihalornethanes during the treatment process(Palmstrom et al. 1988). In a cold water fishery, increased nutrient loading will reduce oxygen in thehypolimnion (Walker, 1979), and cold water species may die off as these populations are driven into warmersurface waters (Colby and Brooke, 1969).

Table 2 presents some of the most sensitive lake uses for each ecoregion. Lakes corresponding to some ofthese categories have been specifically identified in Minn. R. ch. 7050.0470, subp. 1-8 (1980), and includedesignations for the following:

1. Domestic consumption (as defined in Chapter 7050.0220, subp. 2.1); and

2. Fisheries and recreation (as defined in Chapter 7050.0220, subp. 3.2), whereby Class A specificallyrefers to waters designated for the propagation and maintenance of warm or cold water fish, with laketrout lakes specifically identified in Chapter 7050.0420.

Once uses have been defined for a lake, in a given region, appropriate management strategies may bedeveloped. The management strategy for maintaining a given use (phosphorus goal) may vary betweenregions and should reflect user expectations and regional variations in attainable lake trophic state.

For example, drinking water supplies in the Northern Lakes and Forests ecoregion are typically characterizedas oligotrophic to mesotrophic in nature. The cost of treating these waters to produce potable water is muchless than water obtained from eutrophic lakes in central and southern Minnesota. These treatments haveincluded extensive in-lake application of copper sulfate to reduce algal blooms and the use of potassiumpermanganate and activated carbon in the treatment plants to reduce taste and odor (Walker, 1985; Hansonand Stefan, 1984). Even with these treatments, taste and odor complaints are common among users of thesewater supplies. Management strategies for water supplies should focus on decreasing the frequency andintensity of algal blooms.

Regional patterns and user perceptions must be considered when managing lakes for primary contactrecreation and aesthetics. For example, a lake in the Western Corn Belt Plains ecoregion with Secchitransparency in the 1.5 to 2.0 meter range would be considered to have only "minor aesthetic problems", andwould support swimming. In contrast, a lake in the Northern Lakes and Forests ecoregion with thistransparency range would be deemed "swimming im-paired." Using this information in conjunction withregional patterns in lake trophic state, morphometry, and so forth, appropriate phosphorus management goalsmay be set. For the Northern Lakes and Forests, an appropriate phosphorus goal to fully support swimmableuses would be less than 30 µg/L, while in the Western Corn Belt Plains a phosphorus goal of 40 µg/L wouldbe required. However, only a few lakes in the WCBP can achieve a phosphorus concentration less than 40µg/L and thus, a more reasonable goal may be "partial support" of swimmable use which corresponds to aphosphorus concentration less than 90 µg/L.

The phosphorus criteria provide a basis for goal setting and prioritization. For example, lakes currently at orbelow the criteria for their ecoregion will typically support the specified use. These lakes should be protectedfrom increases in phosphorus concentration, beyond natural variability, since even small increases inphosphorus concentration can lead to increased algae blooms and decreased transparency in these lakes. Inmost cases, these changes will be measurable and noticeable to long-time users of the resource. For thoselakes above the criteria, the criteria can serve as goals for restoration. In fact, the recently revised CleanWater Partnership rule (Ch. 7 076.0240 Subp. 4c) notes for lakes in the CWP Program ...'for lakes, an in-lakephosphorus goal defined relative to the ecoregion phosphorus criteria." In this case, the phosphorus criteriabecome the cornerstone for setting goals in these projects. This does not mean that the goals are simplyapplied as written, but goals are developed through the Phase I process and in conjunction with local steeringcommittees. This work is done in an ecoregion context and goals are set accordingly.

Table 3. Minnesota Lake Phosphorus Criteria (Heiskary and Wilson, 1988).

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