American River Assessment + Restoration ReportAmy Weinfurter - Sarah Sugar - Meghan Lewis - Rushyan Yen | December 2014

Existing Recommendations Stakeholder MissionsExisting Management Plans

Future Conditions Riparian and Aquatic Habitat Climate ChangeAging Flood InfrastructureIncreased Recreational Use

Alternative StrategiesEngineered Infrastructure

Natural Measures Residential and Commercial Relocation

ConclusionReferences

Introduction Problem Statement

Goals

River AssessmentScope of AssessmentPhase 1: ContextPhase 2: Site AssessmentPhase 3: Future Conditions

Current Human Use Recreational Use Aesthetic Value Homeless Encampments

Flood Protection

Ecological Concerns

Contents

The Lower American River (LAR) is a highly managed river system: its flows are controlled by releases from upstream reservoirs and its channel is surrounded by the American River Parkway, a managed floodway supporting intensive recreational use. Surrounding the LAR and Parkway is the Sacramento metropolitan area. Natural and human-induced processes have dramatically altered the hydrology, geomorphology and riparian habitat value of the river system, particularly over the last 150 years. State and federal levees in reaches 1 and 2 of the LAR, in combination with upstream dams, provide the City of Sacramento’s only protection from local/private levees and flood flows.

The LAR corridor provides important habitat for resident and migratory fish and wildlife species, a high-quality water source for the local community and the region, a critical floodway for the Sacramento area and a spectacular regional recreation parkway. The beneficial uses of the LAR –particularly its support of fish and wildlife resources—have suffered as a result of historical modifications to the American River watershed and the physical and operational constraints currently imposed on the river.

The American River was identified for study because of its unique placement in an urban area. The portion of the American River we are focusing on is adjacent to the Discovery Park and Cal-Expo public access areas in downtown Sacramento. We will begin with an assessment of this reach, followed by an analysis of the current recommendations for management and restoration of the river. Finally, we will propose our own additions to these recommendations, focusing on how the impact of the flood protection infrastructure on local aquatic and terrestrial ecosystems can be mitigated.

Introduction

Problem StatementThe construction of dams and levees has provided flood protection, water supply, hydropower generation, and recreation opportunities. However, these facilities have also had severe and unintended consequences on the vegetation, wildlife, fisheries, and aquatic habitat of the river. This environmental degradation has further negative consequences on cultural, aesthetic and economic values derived from stream and river systems.

The river’s resources must be carefully managed to sustain and enhance environmental vitality and recreational uses without compromising its role as a flood-control system. The challenges confronting efforts at management of LAR resources are described in this analysis.

GoalsThe goal of our project is to:

• Assess the ARP based on the past, present and projected future conditions of the river reach from Discovery Park to Paradise Beach

• Understand the multi-purpose functions the ARP serves and the dynamic interactions between human, wildlife, vegetation and urban infrastructure

• Identify the challenges faced by channelizing and altering the American River

• Suggest potential management strategies to compensate for changes to the river system, allow recreation, provide flood control protection of the surrounding metropolitan area and maintain the natural resources of the river corridor.

Fig. 1 Scope of the Assessment

Downtown Sacramento

A: Discovery ParkB: Urrutia PropertyC: Discovery Park EastD: Woodlake E: Cal ExpoF: Paradise Beach

Confluence with the Sacramento River

A

C

D

E

F

B

Assessment ScopeOur assessment will focus on the portion of the American River extending from its confluence with the Sacramento River at Discovery Park to Paradise Beach, approximately five miles upstream (See Fig. 1). This portion of the American River is located entirely within the Sacramento Metropolitan Area, confined on either side by levees and urban development.

Phase one of our assessment provides an overview of the American River basin, a description of the American River watershed in relation to adjacent watersheds and California, and a brief history of anthropogenic influences on the river. Phase two provides a detailed site assessment.

Phase One: ContextThe basin of the American River is approximately 2170 square miles (California Stream Stats, 2014). The mean annual precipitation for the basin is 49.2 inches, while average rainfall at our site is 18.51 inches (US Climate Data, 2014). The altitude index is 3.16 thousand feet. The elevation ranges from a maximum of 10,363 feet

River Assessment

Fig. 2 LAR in relation to Sacramento Folsom Lake, and the Sierra Nevadas

to a minimum of 4 feet, with an average basin elevation of 3,806 feet and an outlet elevation of 7 feet. 23.1% of the basin is above 6,000 feet (high elevation index). The mean basin slope is 25.2%, calculated from 30 m DEM.

51.3% of the basin is covered by forest, 1.48% is covered by lakes and ponds, and 11.1% is urban (California StreamStats, 2014). 3.8% of the basin is impervious

area (determined from NLCD 2001 imperviousness dataset), but the Sacramento region of the LAR has a higher impreviousness ratio.

The climate of Sacramento is Mediterranean, with hot, dry summers followed by cool, wet winters, and precipitation varies greatly spatially and temporally (Fairman, 2007). Average rainfall ranges from 46cm/yr (18in/yr) in Sacramento to 178cm/yr (70in/yr) on the slopes of the upper basin (NRC 1995) The temperature ranges from a maximum of 29.8 to 48 F in January for the entire basin. In the Sacramento region where site is located, the annual temperature ranges from a high of 73.6 F to a low of 48.3 F, with an average temperature is 60.95 F (US Climate Data, 2014).

The LAR’s annual discharge averages about 3,750 cubic feet per second (cfs), or about 2,710,000 acre-feet per year, but has varied from 730 to 7,900 cfs. A series of political wranglings over the amount of water to be left in the stream has dictated flow objectives.

The bed of the LAR is dominated by recently deposited, unconsolidated gravel and sand, but gets progressively finer (sands and silts) as it approaches the confluence with the Sacramento River (Fairman, 2007). Bed mobility is primarily limited to large flood events: a two-dimension hydraulic model by Ayres Associates (2001) indicated that flows between 50,000 cfs and 100,000 cfs mobilized and enhanced bed material without signficant volume loss, while in

lower flows the bed was immobile and larger flows led to significant channel widening or depeening (Fairman, 2007) The north side of the river has a bluff composed entirely of bedrock that ranges in height from less than a few meters to more than 50m, limiting the rate of northward migration of the channel. Bedrock consisting of cohesive, poorly consolidated silts and sands, controls the rate of meander development on the LAR and limits the vertical degradation (Fairman, 2007).

Water typically meets quality standards, with occasional exceedances of toxicity standards for selected heavy metals, coliform, chlorpyrifos, and diazonic (Fisheries and Instream Habitat Working Group, 2001).

Brief History of Anthropogenic Influence

The transformation of urban channels can typically be described in three major phases: (1) pre-development phase characterized by a steady state in which sediment and discharge are balanced, (2) active construction characterized by net aggradation in the river resulting in decreasing bankfull dimensions, and (3) urban development characterized by net erosion resulting increasing bankfull dimensions (Wolfman, 1967; Chin, 2005). The history of the American River in response to the development of Sacramento follows these general phases, further complicated by the history of hydraulic mining in the region, which both extended and aggravated what is typically described as the ‘active construction’ phase.

During the first phase of relative channel equilibrium, the LAR was home to many indigenous tribes. The Sacramento Valley was a tidal marsh with abundant terrestrial and aquatic wildlife, including at least 26 species of fish including salmon, sturgeon, chub, tule perch, sucker, and trout in addition to a diverse population of small and large mammals. Early indigenous populations eventually shifted from large mammal hunting to fishing for sustenance, resulting in large populations on the banks of the river.

As the indigenous inhabitants migrated in response to annual flood and drought patterns and harvested salmon without large

Fig. 3 Peak-Flow Streamflow Statistics (Stream Stats, 2014)

REGIONSCENTRAL VALLEYAMERICAN RIVER SUB-REGION

SACRAMENTO RIVER BASIN

AMERICAN RIVER WATERSHED

SCALE

NorthernRegion

North CentralRegion

SouthernRegion

South CentralRegion

Sacramento

environmental impact, anthropogenic influence did not truly begin until the beginning of American settlement of the area in the early nineteenth century. In 1833, a malaria epidemic wiped out 75% of the indigenous population of the Central Valley of California, resulting in approximately 20,000 deaths. Shortly after in 1839, John Sutter began the settlement of New Helvetia in the fertile flood plain southeast of the confluence of the American and Sacramento rivers. By the end of the 19th century, the native populations had been extirpated.

The second phase of active construction extends from 1839 with Sutter’s settlement of New Helvetia in 1839 well into the 20th century as Sacramento expanded into the floodplain of the American River. Land cleared for development began the process of increased sediment load and net aggradation in the rivers. However, the most

drastic shift in the geomorphology of the American River began in the late 1840s with the Gold Rush in California. The Gold Rush had a twofold impact on the American River. First, Sacramento became the jumping off point for gold miners headed into the Sierra Nevadas, increasing land clearing and typical impacts associated with the active construction phase of urban channels. Second, in addition to these more local impacts, the American River received enormous sediment loads from upstream as a result of gold mining.

The alluvial delta beginning in the foothills of the Sierra Nevadas 23 miles east of the confluence were rich in placer gold washed down from the mountains, in addition to gold found further upstream: the sand bars and channel beds of the American River were rich in gold sediment. Mining methods became increasingly intrusive and detrimental to the health of the river as mining increased. Handheld

Fig. 4 Multiple scales of the American River watershed: water diversion and drought have tied the regions of California together, making them interndependent

sieves escalated to sluice boxes extending for hundreds of feet, eventually escalating into the method with the most dramatic impact on the geomorphology of the river: hydraulic mining.

First used in 1855, hydraulic mining involves directing high velocity streams of water at gravel banks, collecting runoff into sluices that sorted gold from the remainder of the sediment. By 1859, the impacts of this method were already felt in the LAR, as the increased sediment yield led to the aggradation of the river such that it was blocked at its mouth. Figure 6 of the Lower American River from 1873 already shows the impacts of urbanization and hydraulic mining. The largest of these machines was developed in 1870, known as the “The Monitor.” In 1879, the Monitor used approximately two million gallons per day over the year, blasting sediment into 640 sluice ditches totaling 6,585 miles (Hayes, 2005). Slickens, the term for the non-gold sediment, added to the increased sediment erosion from land clearing, resulting in an enormous total load on the American River. Awareness of the destructive impacts of hydraulic mining was spurred by the burial of 18,000 acres of fertile agricultural lands in the Yuba under mining debris (Hayes, 2005). The conflict between farmers and gold miners eventually resulted in a ban on hydraulic mining in 1884. However, these regulations took time to have an impact on the geomorphology of the channel: 1896 marks the turning point in aggradation for the channel, when the power of the river was able to mobilize sediment for the first time in decades.

As mining activity led to increasing population and development in the Sacramento region, levee construction increased in tandem with the effects of gold mining, beginning in the 1850s and continuing to this day. The reclamation of swamplands in the floodplain, the extensive construction of levees, and the straightening of the channel to decrease flooding resulted in a highly channelized river. In addition to levee construction, the channel path course was straightened in the mid-1860s, during low flow, by deepening an existing slough to new dimensions 200 feet wide and ¾ of a mile long, beginning opposite 20th Street (Hayes, 2005). In 1905, the Sutter slough was deepened to form main channel, blocking off the previous main channel near confluence to reclaim land. Fig. 5 Impacts of hydraulic mining (Source: River Corridor Management Plan)

Fig. 6 1873 Map of the Lower American River

Fig. 7 1873 Map of the Lower American River overlayed on top of existing satellite image

Over a period of about 15 years, sediment excavated through channel straightening construction projects was used to raise downtown approximately ten feet. As one anecdote describes: “at the height of this activity, Sacramento was described as a city on stilts” (Hayes, 2005).

As development of the floodplain increased, the LAR gradually entered the third and final phase of this process, characterized in particular by the domination of impervious land cover. During this phase there are major hydrological changes due to the introduction of sewers and the destruction of the storage capacity of the land through increased imperviousness. Figure 7 demonstrates the drastic changes from LAR channelization. These changes result in an increased total runoff, impacting the peak discharge of a channel, frequency and magnitude of floods, and lag time. Sedimentological changes also occured as soil in the majority of land is trapped beneath impervious cover and the sediment yield was further decreased by the construction of the Folsom Dam, trapping sediment upstream of the LAR. This increased runoff and decreased sediment yield results in erosion of the channel, which in turn leads to channel enlargement. Channel widening and deepning are still an issue today and will be discussed further in Phase Two.

Phase Two: Site AssessmentThe scope of this project focuses on Reach 1 (as established by the 2002 LAR River Corridor Management Plan), the 6 miles from the Sacramento confluence to Paradise Beach, that lies embedded within the city of Sacramento (See Fig. 1 and 6). Since our team had limited time and access to survey the site directly, our assessment relied on existing research; tools, such as StreamStats, ESRI ArcGIS 10.2 (GIS) analyses, and GoogleEarth, that allowed us to assess the site remotely; and our own impressions and photographs from brief site visits to the Lower American River Parkway during November 2014.

The characterization of urban channels primarily relies on space and time substitution methods. These methods involve taking field measurements on a contemporary urban channel and comparing

measurements to (a) an un-urbanized area with a relationship to the site, (b) upstream or downstream un-urbanized reaches of the same channel, or (c) adjacent natural streams that provide similarities due to their climate, sediment, and potentially watershed.

Given the scope of our project, we were unable to select a suitable reference reach under these constraints. The only reaches for comparison along the American River would be upstream of the Folsom Dam, which makes comparison to the lower elevation and grade in our reach unsuitable. Additionally, there is no historical maps of the area, outside of anecodotal accounts from the first settlers in the valley. These accounts note the river as too shallow for navigation, but otherwise do not provide much data for reference.

Before its historical alteration, this stretch of the river consisted of a “broad, swampy floodplain” (James, 1997), that likely resembled a Rosgen channel type of DA5 and DA6 - that is, a series of braided, slow-moving channels, depositing sediment that had been mobilized further upstream in the river. During the late 19th century, however, the channel in this reach (as well as in Reach 2) was straightened, and the outlet to the Sacramento River was moved further upstream, to increase the distance between this confluence

Slope (Degrees)tinfromcontoursElevation (feet)

71.111 - 80

62.222 - 71.111

53.333 - 62.222

44.444 - 53.333

35.556 - 44.444

26.667 - 35.556

17.778 - 26.667

8.889 - 17.778

0 - 8.889

Elevation71.111 - 80

62.222 - 71.111

53.333 - 62.222

44.444 - 53.333

35.556 - 44.444

26.667 - 35.556

17.778 - 26.667

8.889 - 17.778

0 - 8.889

Elevation71.111 - 80

62.222 - 71.111

53.333 - 62.222

44.444 - 53.333

35.556 - 44.444

26.667 - 35.556

17.778 - 26.667

8.889 - 17.778

0 - 8.889

Fig. 8 GIS Elevation Analysis

and downtown Sacramento (Fairman, 2007). Few changes in the channel’s planform have occurred in this reach since 1900, likely due to the reinforcement of its leveed banks (Fairman, 2007). Given its proximity to downtown Sacramento, the reinforcement of the leveed banks is more extensive in these downstream reaches than in more upstream stretches of the Lower American River (Fairman, 2007).

Reach 1 has a very low gradient and a substrate composed primarily of sand and silt (Williams, 2001). A GIS analysis, shown in Figure 8, found that the elevation of the floodplain within the parkway ranges from 0 to 44.444 feet above the stream’s water level. The stream’s depth is normally controlled by the stage in the Sacramento River, rather than by discharge, and varies with the tide (Williams, 2001). The channelization of both the Sacramento and Lower American Rivers extends the tidal influence farther upstream than would naturally occur. At this point, the majority of this reach of the channel best fits into a Rosgen type F5 or F6 classification, though its channelization prevents much of the meandering typically expected of this kind of system, and also inhibits the formation of pool/riffle system; the first riffle does not occur until river mile five. From 1957 (two years after the installation of the Folsom and Nimbus dams) to 2002, reach 1 widened by 12 percent (Fairman,

Slope (Degrees)tinfromcontoursSlope (degrees)

0.00 - 0.06

0.06 - 0.22

0.22 - 0.51

0.51 - 0.99

0.99 - 1.86

1.86 - 3.44

3.44 - 5.84

5.84 - 13.13

13.13 - 90.00

Edge typeHard Edge

Elevation71.111 - 80

62.222 - 71.111

53.333 - 62.222

44.444 - 53.333

35.556 - 44.444

26.667 - 35.556

17.778 - 26.667

8.889 - 17.778

0 - 8.889

Fig. 9 GIS Slope Analysis

Fig. 10 Incision on the LAR (Site Visit, 11/8/2014)

Fig. 11 Erosion and Net Sediment Loss from 1908 to 1998 Fig. 12 Longitudinal Profile of Reach 1-4 of the Lower American River

2007), spreading its water out into a shallower, broader system. However, the channel’s low gradient, lateral instability, and highly erosive bank correspond with the characteristics typically expected of this kind of stream (Harrelson et al, 1994).

Incision

As with most of the parkway, stream bank incision is prevalent and severe throughout the majority of this reach. A GIS analysis, shown in Figure 9, found that streambank slopes range from 13 to 90 degrees along the majority of the stream. Figure 10 provides a visual depiction of the challenges this incision creates for the establishment of riparian vegetation, and the stark disconnection it creates between the stream and its floodplain. A 1997 study of historical channel incision along the Lower American River found that “flow stages responded primarily to channel aggradation and degradation rather than to changes in roughness elements or energy gradients”(James, 1997). The loss of sediment replenishment (due to the system’s dams) exacerbates the erosive effects of degradation outlined in Chin’s discussion (2006) of urban river systems.

Figure 11 traces erosion from 1908 to 1998 at a cross section 1.6

kilometers upstream from the confluence, in the Discovery Park section of Reach 1, and displays the net loss of sediment that occurred during this time period. Figure 12, a longitudinal profile of incision in the Lower American River Parkway, demonstrates the severity of incision within Reach 1, even relative to high rates of incision in more upstream reaches of the stream.

Temperature

A more detailed look at this reach’s temperature can be approximated from the USGS stream gauge at the Fair Oaks Bridge (while other USGS stations fall slightly closer to this reach, they do not regularly collect temperature data). The anticipated temperature range for 2014, shown in detail in Figure 13, suggests a low of approximately 48 degrees Fahrenheit (ºF), and a high hovering between 65 -70 ºF. An Annual Water Temperature Management Plan, designed to budget available cold water for juvenile steelhead rearing in the summer, and fall-run Chinook salmon spawning in the fall, aims for temperature ranges of:

• 65ºF or less from May 15 through October 31 (for steelhead juvenile rearing); and

• 60ºF or less as early in October as possible (to support Chinook salmon spawning and egg incubation) (Water Forum, 2007).

If analysis suggests that meeting a 65ºF water temperature target will prematurely exhaust the available cold water in Folsom Reservoir, the target water temperature in the summer may be increased by 1ºF increments up to 68ºF from May 15 through October 31, and 60ºF or less as early in October as possible (Water Forum, 2007). Comparing the predicted temperature range with the desired temperatures shows that water temperature typically exceeds the recommended limit of 65ºF from July through October, and typically does not drop below 60ºF until late October and early November.

Floodplain

The floodplain distance was calculated by measuring the distance between the river and the levee at three points spanning the section length, using the “measure distance” tool in GIS, and then calculating the average. The floodplain is generally greater on the left bank,

Fig. 14 GIS Analysis of Floodplain of LAR

LegendEcoDsAreaClip

<all other values>

Area (Square Miles)0.175

0.588

0.655

0.975

1926 feet

276 feet1924 feet

246 feet

2197 feet

502 feet

ranging from averages of 1,924 to 2,197 feet, and more confined by the proximity of the levee on the right bank, where the floodplain distance averages span 246 to 502 feet (see Figure 14 for more details on floodplain extent). In total, the floodplain within the levee confines empasses an area of 2.393 square miles.

The dominant floodplain vegetation includes habitat dominated by cottonwood, alder, herbaceous vegetation, mixed riparian communities, and riparian scrub. A seasonal pond near the confluence with Steelhead Creek also provides another instance of riparian habitat. The characteristics of the ecosystem within the floodplains will be discussed further in Ecological Concerns.

Managers divide this reach up further, into the sub-reaches of: Discovery Park, the Woodlake Area, the Cal Expo area, and Paradise Beach. Given its proximity to downtown Sacramento, reach 1 is one of the most heavily trafficked areas of the park.

12/7/2014 waterdata.usgs.gov/nwis/dv/?dd_cd=01_00010_00001,01_00010_00002,01_00010_00008&format=img_default&site_no=11446500&set_arithscale_y=on&pe…

http://waterdata.usgs.gov/nwis/dv/?dd_cd=01_00010_00001,01_00010_00002,01_00010_00008&format=img_default&site_no=11446500&set_arithscale_y=on&per… 1/1

Fig. 13 USGS Fair Oaks Temperature Data

Recreational UseThe American River Parkway (ARP), extending 31.5 miles from the conconfluence with the Sacramento River to Beal’s Point in Folsom Lake State Recreational area, is an important recreational resource for the Sacramento region. The ARP includes more than 4,600 acres of parkland with multi-use trails, picnic areas, boating access sites, swimming areas, gold courses, a group camping area and a nature center. The LAR corridor, with its natural beauty, proximity to an urban population, and recreational values, has been designed a “recreational river” in both the federal and state wild and scenic river systems. The trail system of the Parkway has been designed a “National Recreational Trail.”

The first mention of the park ocurred in 1915 by John Nolen, a Sacramento City Planner, followed by a complete proposal by Olmsted Jr. in 1947 as part of his park assessment of all of California (Hayes, 2005). In 1949, a River Beautification Committee formed and began acquiring land, fully adopting the idea of parkway in 1959. The California legislature in 1985 acknowledged the Parkway’s statewide significance by adopting the Parkway Plan through the passage of the Urban American River Parkway Preservation Act.

Recreational activities permitted in the Parkway are designated

Human Use

by five categories: Nature Appreciation, Recreational Enjoyment (such as picnicking and camping), Trails Recreation, Recreational Participation in Group Sports and Athletics, and Aquatic Recreation (ARP 2008). Trails recreation is the most popular activity in the Parkway. The Jedediah Smith Memorial Trail is the primary recreational trail and runs along the entire length of the Parkway. It connects Discovery Park to Folsom Lake and provides an important bicycle commuter route.

Aquatic recreation access and facilities are permitted in the Protected, Limited Recreation and Developed Recreation land use categories of the ARP. In Protected Areas, all aquatic recreation activities are permitted except motorized boat launching. Typical aquatic recreation includes recreational fishing for steelhead, Chinook salmon, American shad, and striped bass. These fish are pursued from boats, the bank, and by wading. In addition, commercial guided fishing boats offer drift-fishing trips on the river. Populations of largemouth bass, bluegill, crappie, sunfish, catfish and other recreational fish, thrive in certain dredger tailing ponds where the water is deep enough to meet oxygen and temperature requirements. Fishing is permitted in these ponds, unless otherwise noted on an area plan.

Discovery Park

Located at the northern border of the city of Sacramento, Discovery Park proper is substantially developed and is one of the most intensively used areas of the Parkway. Amenities include a six lane boat access ramp and parking area, information kiosk, and fish cleaning facility at the western end, a large turfed picnic area for families and groups in the central portion, and a field/target archery range and equestiran staging area at the eastern end. Discovery Park is accessed from the I-5 freeway and the Jibboom Street Bridge or by foot from downtown Sacramento.

As the region grows and land uses adjacent to the Parkway become more densely developed, there will be greater numbers of Parkway users. Detrimental impacts on natural resources from increased use are a concern for the entire parkway, particularly in Reach 1. Higher density uses are planned in areas adjacent to the Parkway as part of the City of Sacramento’s goal to create more vital urban neighborhoods, which in turn supports the goal of the Regional Blueprint to reduce urban sprawl by intensifying existing developed areas.

Fig. 15 Subreaches of the LAR as defined by park managers

behind flood control levees, or is at roughly the same elevation as the Parkway. Infrastructure such as highways and bridges are the primary reminder within the ARP of its physical context.

As visible in Figure 16, this creates a sensation of isolation in a natural environment that is rare in an urban context. However, as high density development increases, the visual isolation of the ARP from its surrounding will continue to decrease. On the south side of the river is the downtown core of the Sacramento metropolitan region. In this area, views of the river adn the Parkway are juxtaposed with views of downtown high-rise buildings and urban infrastructure within the ARP itself. This area in particular reminds visitors of the ARP’s value as an open space greenbelt preserved in the urban core.

Woodlake Area

The Woodlake Area became publicly owned after the adoption of the previous Parkway Plan, and therefore, has minimal developed recreation facilities in comparison to other areas in the Parkway. There are two public access points, one at the east end of the area with paved parking at the eastern end of Northgate Boulevard and the other centrally located and without parking off of Expo Parkway. The area is also traversed by a paved bicycle trail and an equestrian/hiking trail.

Cal-Expo Area + Fairgrounds

Cal Expo maintains an 11 acre unsurfaced parking area in the northeastern portion of the property adjacent to the levee for the State Fair, the only area within the Parkway land permissible for outsider parking use. The remainder of this property is dominated by Bushy Lake and not heavily used for recreation.

Paradise Beach

Paradise Beach is a popular area for fishing, wading, sunbathing, volleyball, and similar beach activities. A network of informal trails interconnects popular sunbathing spots in the area. A narrow channel cut through the easternmost tip of the beach area has been used on occasion as a slalom course for kayakers. There are no permanent structures in the area. Access to Paradise Beach is limited. The entire area is served by one parking lot which is located at Glenn Hall Park, a City-operated park abutting the Parkway.

Aesthetic ValueThe Parkway’s open spaces and natural resources provide Parkway users with a highly-valued natural setting and feeling of serenity, in the midst of a developed urban area. The Parkway’s aesthetic resources, while difficult to define, are a curcial resource to the Sacramento region.

Much of the areas adjacent to the Parkway are residential, suburban neighborhoods. This type of development is often partially screened

Fig. 16 Visual isolation of the LAR from surrounding residential development (Site Visit 11/8/2014)

including the Sacramento City Main Pumping Station, are located along the river.

The Woodlake and Cal-Expo areas are crossed by several major transmission lines and their support towers. Unpaved maintenance roadways provide access to the utility easements and serve as firebreaks and informal trails.

Homeless EncampmentsHomeless camps in Reach 1 of the ARP have become an increasing presence and management issue, and park managers divert funds and ranger positions towards engaging with this population. Illegal camping is especially common in the westerly five mile reach from Discovery Park to Cal Expo, with the largest concentration in the area of the Highway 160 crossing of the American River. In 2012, chief ranger Stan Lumsden estimated that 500 people camped in the park each night (Bienick, 2012).

Rangers note concerns about trash and unattended camp fires that can spark wildfires. A lack of viable alternatives for shelter in the surrounding city, and a political reluctance to provide facilities (such as trash cans and fire pits) that might reduce incidences of trash and fire within the parkway, have limited the options for responding to this management challenge, and made this an increasingly entrenched issue.

Vegetative clearing and harvesting woody materials for firewood cause disturbances to vegetation in and around illegal campsites. These disturbances, including litter, waste and debris, alter the structure and function of the riparian woodlands, may affect plant establishment, impact recreational experiences, degrade water quality, and discourage wildlife from using otherwise suitable habitat.

Public UtilitiesThe American River not only carries run-off from the Sierra Nevada Mountains, but also accepts run-off from the urban areas that it flows through. Local run-off is carried to the river by way of natural streams, underground culverts and lined channels. Local drainage outfalls to the river can be described a number of different ways: drainage cascading down open rock slopes, flowing from protruding culverts through gate valves and sometimes drainage flows through vegetation so dense that flows cannot be seen, only heard.

The LAR is crossed by electrical lines, sewer trunk lines, water lines, and other public utility facilities. Several pumping stations,

The LAR traverses a large floodplain covering over 100,000 acres east of the Sacramento River. Most of this floodplain has been extensively developed for urban use. These urban developments, which have a structural value in excess of $30 billion, are protected from flooding by Folsom Dam and the levee system running along the east side of the Sacramento River, the north and east sides of the Natomas Basin, and the north and south sides of the LAR. These facilities are part of a much larger Federal/State flood control system in the Sacramento Valley administered by the U. S. Army Corps of Engineers (Corps) and the California Reclamation Board (Reclamation Board).

Along the LAR, Federal and State levees extend from the mouth of the river to high ground about 13 miles to the east. Levee construction began as early as 1850 in response to increased population in Sacramento due to gold mining. Increases in sediment from hydraulic mining resulted in an aggraded channel, increasing the likelihood of the river flowing into the flood plain during peak flows. However, simultaneous to the channel aggradation was the reclamation of swamplands in the floodplain and the restriction of the floodplain to a limited width between levees. Land “reclamation,” i.e. development of the floodplain, began as piecemeal project from 1850-1900 by farmers and communities but escalated

Flood Protection

Fig. 17 Chronology of Dams (Source: River Corridor Management Plan)

)*+,-80

§̈¦5SacramentoRiver

American River

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Arcade Creek

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RICHARDS BLVD.

NM

DE

C

ARDEN WAY

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0 2,000Scale in Feet

Inundation Boundary

40,000 (cfs)(Sacramento River at 15ft)

40,000 (cfs)(Sacramento River at 20ft)

40,000 (cfs)(Sacramento River at 25ft)

Floodway Inundation Boundaries forAmerican River Operational Flow of 40,000 cfs

Figure 1 of 3Date Saved: 2/18/2014 10:40:11 AMPath: R:\4890.70 SAFCA - Folsom Modification\2013-11 LAR Inundation Mapping\ArcMap\Floodway Inundation Boundaries for Key American River Operational Flow Rates.mxd

American

NE

MD

C

FolsomLake

RiverSacramentoR

iver

[Sacramento

13

2

Floodway Inundation Boundaries for Key American River Operational Flow R (5)Source: SAFCA - Folsom Modification\2013-11 LAR Inundation Mapping\ArcMap\Floodway Inundation Boundaries for Key American River Operational Flow Rates.mxd

Fig. 18 Floodway Inundation Boundaries Key American River Operational Flow (Source: Sacramento Area Flood Control Agency, 2013)

quickly in response to the construction of levees and the Swamp Land Act, which required all profits from swamp land sales to be used for reclamation of the swamp land. Increased discharge and the restriction of the channel through levees led to disastrous floods in 1862, 1867, 1875, and 1878. Each flood brought increases in the height of levees, in an attempt to combat the impact of increased overtopping of the river due to channel aggradation.

The south side levee and the lower portions of the north side levees originated in this time period prior to the completion of Folsom Dam. These levees were designed to contain floods capable of producing peak flows up to 180,000 cubic feet per second (cfs)

with three feet of freeboard between the water surface and the top of the levee. Toward this end, the north side levees were set back a considerable distance from the river channel. After the completion of Folsom Dam in 1956, the last segment of the Federal/State levee system was constructed along the north side of the river between Cal Expo and the Carmichael Bluffs. Relying on the regulating effect of the dam, this levee was placed relatively close to the river and the newly confined channel was designed to contain flows up to 115,000 cfs with at least five feet of freeboard, or 152,000 cfs with at least three feet of freeboard on both sides of the river. In the mid-1970’s, private developers constructed the south bank levee upstream of the Mayhew Drain to allow development of the adjoining floodplain.

lowering the depth of the channel bottom until it reached more stable hard pan. This was accomplished shortly after the completion of Folsom Dam. Since then, the river has proceeded to widen its channel by scouring the sediments comprising its banks and berms.

Throughout the lower portion of the Parkway, this pattern of erosion has produced a relatively narrow low flow channel that is confined by steep, often unstable banks that rise to an elevated, irregularly inundated floodplain. This erosion can threaten the stability of levees that have been placed relatively near the channel, such as on the north side of the river (right bank) upstream of Cal Expo and on much of the south side of the river (left bank). Because these levees are hemmed in by urban subdivisions, flood managers must halt the erosion. The Parkway Manager also has an interest in protecting threatened berms that support remnant stands of cottonwood forest and provide recreational access to the river. The consequence of failing to protect these berms is evident on the south side of the river (left bank) just upstream of the Capital City Freeway. There, the high flows generated by the flood of 1986 removed a sizeable berm that once buffered the nearby levee, provided shaded riverine aquatic habitat and supported an informal recreational trail. In the aftermath of the flood, emergency repair crews restored the waterside slope of the levee by placing engineered rock extending from the top of the levee to the river channel, creating a large gap in the riparian corridor occupying this portion of the Parkway.

Reach 1 of the American River is confined to a 2,000-3,000 foot floodplain, but it generally does not have limited floodway capacity (according to 2002 runoff and discharge estimates). The flow velocities remain relatively low during maximum objective release of 115,000 cfs from Folsom Reservoir (RCMP, 2002, p. 49).

This levee was designed to contain a flow of about 130,000 cfs with three feet of freeboard.

Dams, including Old Folsom Dam (completed in 1893), North Fork Debris Dam (completed in 1939), and the modern Folsom Dam and Nimbus Dam (part of the Central Valley Project completed in 1955), and the levee system were constructed, in part, to provide flood protection to the Sacramento metropolitan area, which was built largely in the river floodplain.

Folsom Dam as it exists today was first proposed as part of the State Water Plan of 1931 in response to the droughts impacting agriculture in the Central Valley in the 1920s. Folsom had already been the site of previous powerhouses: the electricity generated from the Folsom Dam powerhouse in 1895 resulted in the first long distance transmission of electrical power, traveling 22 miles from Folsom to Sacramento.

In 1944, the Flood Control Act authorized the US Army Corps of Engineers (USACE) to construct a one million acre multi-purpose dam and reservoir with a 162 KW power plant, regulating dam, and downstream power plant at Nimbus. Upon completion of the dam, USACE transferred control of the dam to the Bureau of Reclamation, who also constructed the Folsom Power Plant, Nimbus Dam, and Nimbus Power Plant downstream from Folsom to help regulate flow and water intake.

Erosion of the berms and banks supporting the levees along the LAR is an ongoing threat to the stability of the flood control system that has been heightened by the need to convey very high flows through the system for sustained periods as part of the program to provide a high level of flood protection to the urbanized floodplain. As discussed in Phase One of our assessment, the LAR is a highly degraded river channel. The legacy of hydraulic mining in the watershed, the operation of Folsom Dam, and the urbanization of the protected floodplain has severely aggravated the channel Regulation of hydraulic mining practices and the subsequent construction of Folsom Dam drastically reduced the rate of sediment transport and caused the lower river to scour the sediment deposits, steadily

table is now greater than before stream channel degradation. Thus, while vegetation colonized the floodplain during the period of aggradation and the mature plants with deep root systems continue to grow today, a limited amount of natural regeneration of the riparian forest is taking place as a result of the floodplain being inundated less often and the water table being deeper. As a result, historically riparian habitats are converting to upland habitats.

• The reductions in sediment supply have affected the soil material required for plant establishment and growth. No major streams are tributary to the LAR downstream of the sediment-trapping reservoir, resulting in little sediment for the development of new habitat along the edges of the main river channel. All of the new sediment is currently derived from bank erosion.

• The amount of non-native invasive vegetation has increased steadily; in some cases it is outcompeting native vegetation. The result is a reduction in the overall quality of vegetation communities and wildlife habitats.

• Parkway habitat values are diminished by the spread of invasive weeds and the destruction of native plants, fish, and wildlife as a result of inadequate regulation of human activity in sensitive and

The construction of dams and levees has provided flood protection, water supply, hydropower generation, and recreation opportunities. These facilities have protected the city of Sacramento from major floods and currently protects more than $30 billion in commercial, industrial, and public buildings as well as more than 400,000 people residing in the historic floodplain. However, the infrastrucutre has also had severe and unintended consequences on the vegetation, wildlife, fisheries, and aquatic habitat of the river.

Floodplain HabitatThe floodplain of the American River in Reach 1 is confined to approximately 2,000 - 3,0000 feet by federal and state levees, primarily located on the right bank. Current threats to existing high-quality native riparian vegetation include non-native species, littering, and fire, both from drought and illegal camping. Fire has recently had enormous impacts on the terrestrial parkway ecosystem, destroyed mature stands of riparian forest and woodland.

The River Corridor Managment Plan (2002) has highlighted these concerns for vegetation:

• The floodplain in places is now considerably higher than the adjacent channel bottom. Therefore, the distance to the water

Ecological Concerns

densely vegetated areas of the Parkway and inadequate funding to enforce regulations. Problems associated with illegal use of the Parkways should be addressed systematically throughout the PArkway so that they are not transferred to other ecologically sensitive areas.

• Uncontrolled feral cats and dogs diminish habitat values and threaten native wildlife. Deer, coyote, beaver, and other native wildlife could diminish habitat values if their populations exceed the Parkway’s carrying capacity.

To give a more lengthy description of the ecological health of the site, we have used the subreaches as estalbished by RCMP.

Subreach 1a (RM 0 – 1.0), Discovery Park, is comprised primarily of high-quality cottonwood, mixed riparian forests, and early to mid-successional riparian scrub habitat. A seasonal wetland is located at the eastern end (about RM 1.0). In Discovery Park, illegal and legal human uses including illegal camping, fires, a boat launch, recreation and picnic areas, protected natural areas, and archaeological sites impact habitat health.

Subreach 1b (RM 1.0 – 1.8), Urrutia Property, contains an 82-acre pond resultant from a sand and gravel mine on the high floodplain. Major features include mature cottonwood and mixed riparian forests north of Urrutia pond and on the left bank, a narrow strip between I-5 and State Route 160. Vegetation management action is severely limited in this subreach by private property on the right bank and by transmission lines, underground utilities, and other structure. A reclamation plan for the Urrutia Property must be developed under the Surface Mining and Reclamation Act (SMARA) in coordination with the City. The undeveloped shoreline on the left bank (Jibboom Street East) is popular for fishing, picnicking, and boat anchoring, which has occasionally caused safety issues due to the density of vegetation.

Subreach 1c (RM 1.8 – 2.0), Discovery Park East, contains a large restored seasonal wetland/riparian area, entry point the Natomas East Main Drainage Canal (NEMDC or “Steelhead Creek”), several utility easements, and two private properties, the Riverdale mobile

home park and Camp Pollock, a Boy Scouts of American (BSA) camping site. Aside from the constructed wetland along Northgate Boulevard, there is little quality habitat due to the easements and private property. Vegetation management action is severely limited in this subreach by private property on the right bank and by utility easements.

Subreach 1d (RM 2.0 – 3.7), the Woodlake Area, contains moderate- to high-quality willow riparian scrub and cottonwood and mixed riparian forests along both banks of the LAR and an urban drainage channel along the levee at the northern edge of the park, a broad floodplain dominated by ruderal grasses and infested by many nonnatives such as pepperweed and yellow star-thistle, and a seasonal wetland in a floodplain depression with degraded habitat. A high berm limits periodic inundation of the floodplain causing fish stranding after high water. In addition to these concerns, the area was intensively farmed until the mid-1900s and farmed for hay until 1998. Public roadways, private railroads, transmission lines, and radio towers compounded by illegal camping, fire, and invasive weed species have overall lead to a very degraded habitat. As a result, Woodlake area is considered a high-priority site for habitat restoration. Extensive legal camping has reduced habitat value through trampling, garbage, and cutting of vegetation for fuel, recent fires have burned riparian forest and woodland stands, and the invasive species pepperweed has established in large areas of abandoned agricultural fields

Subreach 1e (RM 3.7 – 5.5), Cal Expo, is dominated by Bushy Lake, a shallow pond resultant from a former borrow site (soil excavation) and golf course development bordered by moderate quality old-growth cottonwood riparian woodland and dense willow riparian scrub. The area supports seasonal and perennial wetland communities. The right bank contains high-quality early to mid-successional willow riparian scrub and cottonwood and mixed riparian forest habitats. The left bank was subject to major erosion during floods but has been protected since, aiding erosion but further impacting wildlife habitat by the addition of sterile riprap environments. Habitats also compete with several infrastructure projects, as the subreach is bounded by the Southern Pacific Railroad

Fig. 19 Reach 1 Moderate to High Quality Habitats

Fig. 20 Reach 1 Degraded Habitats

high-velocity flows during high discharge events, which limits vegetation on the point bar and erodes fine-textured material, resulting in a naturally armored, cobble surface that limits vegetation establishment. Figure 19 demonstrates the clustering of the moderate to high quality habitat that does exist along the banks of the LAR, constructed wetlands, and drainage channel, evidencing the importance of annual flooding and water to the health of the floodplain habitat.

The degraded habitat (see figure 20) within the floodplain is due to excessive human use, historic industrial use (including sand and gravel mines and use as a borrow site), and historical agricultural use that have left the ARP vulnerable to excessive damage from fire and invasive species.

tracks on its western edge and the extension of Ethan Way on its eastern edge, in addition to being crossed north to south by the Capital City Freeway and east to west by transmission lines. Recent wildfires have degraded many stands of cottonwood/willow riparian woodland/scrub.

Future long-term management and ownership of this area must be determined in negotiations between the County and the Cal Expo board of directors. Management of lake water levels are dictated by the Bushy Lake Protection act and maintained by Cal Expo through groundwater pumping. Any development of the area must be consistent with development permitted under the Bushy Lake Preservation Act

Subreach 1f (RM 5 - 6), Paradise Beach, is a large sandy beach created by a point bar deposit, scattered with pockets of willow riparian scrubs. Mature cottonwood and mixed riparian forests exist on the downstream end of the bar. The right-bank portions contain moderate-quality mixed riparian forest. The bar experiences

Fig. 21 Reach 1 Aquatic Habitats

Aquatic Habitat In addition to the river itself, a variety of aquatic habitat exists within the parkway. Within the river, aquatic habitat diversity increases after the first riffle at approximately RM 5. Wetland habitats are available at the Bushy Lake site in the Cal Expo subreach and the constructed wetland at the outlet of the Natomas East Main Drainage Canal. Only portions of the parkway are flooded annually, and separation of the floodplain from the river due to incisement has created stranding issues.

43 native and nonnative fish species have been documented in the reaches of the LAR. Nineteen of the 43 documented species in the LAR are “numerous or common” in at least certain portions of the waterway; nine are classified as present or occasional; 14 are considered as few, uncommon, or rare; and one, the thicktail chub, is extinct. Anadromous species, including the steelhead salmon, which is listed as a threatened species by the federal Endangered Species Act, and the fall-run chinook salmon, which is classified as a species of concern, are of primary concern due to their declining numbers, and importance to recreational/commercial fisheries. Previous to anthropogenic alteration of the river, the LAR provided 125-160 mi of fish habitat available for spawning, supporting an estimated 130,000 plus salmon runs. Post alteration (1944-5), salmon runs average 26,500, 73% between Folsom and Nimbus, with a recent low of 11,000 winter of 1991 and high of 1170000 winter of 1987-8 (Hayes, 2005). In 1961, the Nimbus Fish hatchery was built to replace fish habitat after the construction of Folsom Dam.

The historical and current alterations to the LAR create a series of daunting challenges for the survival of aquatic life. It is important to note that many of these effects are deeply interconnected. Lowered flows, for instance, also contribute to higher water temperatures, and to reductions in the amount of available habitat. Overall, however, the impacts of channel alterations on aquatic life fall under the key overarching categories of: changes in flow regimes, increasing water temperatures, and degraded riparian and in-stream habitat.

Fig. 22 AFRP Flow Objectives for the LAR (Source: William, 2001)

Fig. 23 Estimated natural monthly flows compared to current (as of 2001). Alter-ations to the system have reduced overall volume, as well as the variability across the year. (Source: Williams, 2001)

Changes in Flow Regimes

The decrease in the volume and variability of the river’s flow forms perhaps the most drastic and far-reaching challenge for fish survival. In a review of flow effects on salmonids, Nislow and Armstrong (2012) found that a lower flow flow during the early emigration period was associated with lower growth and survival. Changes to flow regimes pose dangers to aquatic life, both directly, through stranding, and indirectly, through a contribution to rising water temperatures. Runoff typically comes from winter rains at lower elevations and from spring snowmelt at higher elevations. Winter storms can trigger sudden high flows throughout the watershed. The LAR’s annual discharge averages about 3,750 cubic feet per second (cfs), or about 2,710,000 acre-feet per year, but has varied from 730 to 7,900 cfs. A series of political wranglings over the amount of water to be left in the stream has yielded the flow objectives articulated by figure 22.

The LAR’s reduced flow rate creates challenges for fish by lowering water levels. Lower water levels can leave fish “stranded” after high flood events; that is, the rapid rise and retreat of water leaves juvenile fish unable to migrate back into the main channel after the storm event ends and the water recedes. Lower water levels also make the stream more prone to solar warming, particularly given its broad, shallow geomorphology. Solar warming lowers dissolved oxygen levels and increases the thermal stress on fish.

Temperature

In addition to the connection between lowered flows and opportunities for increased solar gains, discussed in the section above, the Folsom and Nimbus dams release water that has been warmed by its time in the lakes behind these dams. Elevated water temperatures lead to a range of dangers for fish, and particularly for anadromous species. For anadromous fish, such as steelhead and chinook salmon, water temperatures form an important cue signaling migration from the river into the Pacific Ocean. Prematurely warm temperatures prompt earlier out-migrations; a trend towards earlier migration since the 1945-1947 period is currently thought to be a

Fig 24 (adult fall run chinook salmon) and Fig 23 (steelhead): Illustration of the dif-ferent overlaps between chinook and steelhead salmon’s spawning cycles, and the temperature, flow, and habitat stressors along the LAR. (Source: Initial Fisheries and Aquatic Habitat Management and Restoration Plan for the LAR, 2001.)

result of the temperature impacts from the Folsom and Nimbus Lakes. As a 2005 report notes, “during chinook and steelhead rearing outmigration temperatures can result in multiple indirect effects, including increased risk of predation, decreased growth rates, starvation, and susceptibility to disease, all of which contribute to reduced juvenile survival.”

Managing the dams for improved fish survival is complicated by the differences in their life cycles. As one study points out, “because Folsom Reservoir has a limited quantity of cold water, managing release temperatures for the sole benefit of steelhead in the summer could adversely affect fall-run Chinook salmon spawning in the fall. Conversely, conserving cold water throughout the summer and releasing it in the fall could benefit Chinook salmon, but would result in adverse high summer temperatures for steelhead.” (See figures 23 for a more detailed comparison between these species’ life cycles and the temperature limitations of the Lower American Parkway). In other words, it is difficult to manage for multiple populations of fish simultaneously, given the restrictions and high level of demand for water from the reservoir.

Reduction of Riparian and In-stream Habitat

Given reach 1’s low gradient, it is primarily suitable for fish rearing, rather than spawning, habitat, although river-adjacent flooded vegetation thought to be a key component of Sacramento splittail spawning habitat (Water Forum Final State Report). The reduction of appropriate rearing habitat occurs through many different avenues. A State Report from the Sacramento Water Forum notes that “bank erosion, channel degradation and creation of riprap revetments have contributed to the decline of riparian vegetation along the river’s edge, loss of soft bank and channel complexity, and reduced amounts of large woody debris in the river that are used by fish and other species” (Water Forum Final State Report). Most concerning for fish, overhanging bank vegetation or shaded riverine aquatic (SRA) habitat has declined especially dramatically. SRA provides fish habitat; provides shade along the river to moderate water temperatures in the summer; and offers cover by creating

areas where aquatic species “can feed and rest while being sheltered from predators” (Water Forum Final State Report). Living and dead vegetation also provides habitat and food for many species of insects and other organisms, which can then be eaten by fish species including salmonids. In other words, the lack of SRA disrupts several critical trophic points in this reach’s aquatic ecosystem.

In addition to a lack of riparian habitat within the river, impacts to the channel prevent it from connecting to seasonal pools and wetlands. As Zueg et al discuss in a study of juvenile Chinook salmon, “a lack of access to off-channel habitats in years with low discharge and discharge variance may partially explain why low survival indices were observed. Higher velocities within the main channel may also reduce exposure time of migrating juveniles to predation within a specific stream reach” (2014). The disconnection between the stream and floodplain -- that is, the presence steep banks, separated by sharp drops in elevation, rather than a more graded and gradual path to the stream -- can also contribute to stranding.

This lack of habitat creates an unfortunate feedback loop, fostering increased competition among fish, and further stressing juvenile populations. A presentation by representatives from the U.S. Fish and Wildlife Service and the Department of the Interior needed the need for additional rearing (and spawning) habitat to “ease competition among fish” within the Lower American River (citation). Restoring habitat in this reach would both move the river closer to its natural state, and fill a key niche within fish life cycles in this river’s ecosystem.

Fig. 25 Reach 1 Human Use conflicts with restoration potential along the ARP

Barriers to RestorationFigure 25 demonstrates the numerous barriers to restoration that increase ecological concerns. Despite the best intentions of parkway managers, extensive flood protection measures (levees and riprap in particular), transmission lines, private property, and vehicle infrastructure obstruct their ability to restore the floodplain habitat.

parkway to mitigate human impact on the park ecosystem, we will focus primarily on the vegetation and wildlife recommendations provided in the RCMP (2002).

River Corridor Management Plan (RCMP)We have summarized the actions of the RCMP relevant to Reach 1 by dividing them according to action as follows.

Protection

• Protect existing mature cottonwood and mixed riparian forests on Bannon Island/Bannon Slough, early to mid-successional riparian scrub habitat between I-5, the right bank of the LAR, and the bike trail, and the existing seasonal wetland between the bike trail and Urrutia Pond (Veg 1, 1a)

• Protect existing riparian scrub and mixed riparian forest along Bannon Slough, along Northgate Boulevard, and along the left bank (Jibboom Street East) (Veg 1, 1b)

• Protect willow riparian scrub and cottonwood and mixed along the LAR and drainage channel, valley elderberry longhorn beetle mitigation sites, and bank-protection mitigation sites (Veg 1, 1d)

Mission of American River Parkway Managers The Parkway Concept can be summarized as follows:

The American River Parkway is a unique regional facility which shall be managed to balance the goals of: a) preserving naturalistic open space and protecting environmental quality within the urban environment, and b) contributing to the provision of recreational opportunities in the Sacramento area. Overall guidance on the approach to preservation and management of the Parkway are embodied in both the Plan’s Goals and the Concept Policies. (ARP 2008)

The LAR Task Force (LARTF) focuses on flood, environmental and recreational management issues affecting the lower reach of the American River from Folsom Dam to the Sacramento River. In 2002, LARTF participants cooperated in preparing the LAR Corridor Management Plan (RCMP) to provide a framework for integrated management of this reach of the river.

An additional plan, the American River Parkway Plan, was published in 2008 by County of Sacramento Planning and Community Development Department. As the ARP Plan (2008) focuses primarily on establishing land use designations within the

Existing Recommendations

• Establish valley oak riparian woodland or cottonwood and mixed riparian forest habitats in Riverdale mobile home park area (Veg 19, 1c)

• High-priority site for expanding target vegetation (grassland + oak woodland) (Veg 2, 1d)

• Restoration of the drainage channel from Sump 151 (Veg 2, 1d)

• Establish perennial and annual grasslands, oak woodlands, and elderberry savanna below transmission lines (Veg 5, 1d)

• Restore wetland/slough complex habitat in Bushy Lake area to provide multispecies benefits (Fish 11, 1e)

• Establish valley oak riparian woodland over much of the area currently in grassland and not under transmission lines (Veg 2, 1e)

• Expand willow riparian scrub and cottonwood and mixed riparian forest around existing wetlands and in suitable low-elevation sites adjacent to the right bank of the LAR (Veg 2, 1e)

• Establish annual grasslands and/or elderberry savanna under transmission lines and in areas with potential floodway conveyance constraints (Veg 2, 1e)

• Establish elderberry savanna in annual grasslands below transmissions lines and in areas with floodway constraints to prevent expansion of invasive species into these areas (Veg 4, 1e)

• Establish new alder/willow riparian scrub and cottonwood and mixed riparian forest in suitable elevations at Paradise Beach where compatible with flood conveyance capacity, public safety, and recreation use (Veg 2, 1f)

Grading:

• Minor grading to lower the elevations of the surface of areas along and south of Bannon Slough by 2-4 feet to create suitable floodplain habitat for cottonwood and mixed riparian forests, also allowing drainage to Bannon Slough to provide enhanced

• Protect existing overflow areas to maintain floodplain habitat (Fish 12, 1c)

• Protect constructed seasonal wetland along Northgate Boulevard (Veg 1, 1c)

• Protect existing willow riparian scrub and cottonwood and mixed riparian forest adjacent to Bushy Lake and the right bank of the LAR (Veg 1, 1e)

• Protect existing cottonwood and mixed riparian forest adjacent to wetland and the right bank of the LAR (Veg 1, 1f)

• Protect cottonwood and mixed riparian forest and willow riparian scrub at Paradise Beach and downstream along the left bank (Veg 1, 1f)

Decrease Homelessness:

• Reduce illegal camping (Veg 1, 1a, 1d)

• Support more aggressive enforcement of existing laws to protect important habitat values and endorse the allocation of Sac County Park Rangers to the Woodlake area, particularly along the right bank in the mixed riparian and black walnut habitats (Veg 7/Rec 15, 1d)

Establish New Habitats/Restore Degraded Ones:

• Establish valley oak riparian woodlands in open areas along and south of Bannon Slough (Veg 2, 1a)

• Establish valley oak riparian woodland adjacent to the right bank (Veg 2, 1a)

• Remediate the abandoned trail along Bannon Slough and restore cottonwood and mixed riparian forest (Veg 19, 1a)

• Reduce or eliminate stranding where opportunities exist (Fish 12, 1c-d)

• Establish shallow inundated floodplain habitat for multispecies benefits where suitable opportunities are available (Fish 12, 1c-d)

• Relocate bike trail away from LAR bank (Veg 9, 1a)

• Redesign or relocate portions of the sand and gravel facility on the left bank of Woodlake area to improve riparian habitat (Veg 19, 1d)

Monitoring

• Complete inventory of areas that pose a stranding threat to juvenile salmonids (Fish 8, 1c-d)

• Inventory locations for creating shallow inundated floodplain habitat for multispecies benefits (Fish 12, 1c-d)

Call For Further Planning

• Conduct function analysis workshop to identify measures to reduce or eliminate stranding and implement opportunities where they exist (Fish 8, 1c)

fish habitat (Veg 2 and 11, 1a)

• Grade down 6-8 feet to create suitable floodplain habitat for cottonwood and mixed riparian forests (Veg 2 and 11, 1a)

• Reduce gradient of over-steepened bank immediately downstream of the Urrutia Pond (Veg 9, 1a)

• Grade connection between existing seasonal wetland the right bank of LAR to create positive hydrologic drainage and reduce stranding (Veg 11, 1d)

• Grade areas presently suitable for valley oak riparian woodland to lower surfaces and make them suitable for cottonwood and mixed riparian forest (Veg 11, 1e)

Removal

• Remove infestations of non-native weeds (Veg 1, 1a, 1d)

• Remove nonnative species from cottonwood and mixed riparian forest along the left bank (Veg 3, 1a)

• Remove nonnative species from left bank (Veg 3, 1b)

• Remove yellow star-thistle and pepperweed (Veg 3, 1d)

• Establish fuel breaks and access routes for fire suppression (Veg 1, 1a)

• Control vegetation impeding public and levee-inspector safety: a vegetation-thinning project along narrow left-bank floodplain of Urrutia Property to be replaced by a public trail (Flood 12, 1b)

• Remove exotic noxious weeds, especially yellow star-thistle, from open grassland areas (Veg 3, 1e)

• Control and mitigate herbivore to riparian woodlands along left bank of LAR (Veg 15, 1e)

Relocation

• Relocate the Riverdale mobile home park (Veg 19, 1c)

Future Conditions

previous chapters have created a new set of influential conditions to which the river is adjusting. It is apparent that channel and riparian vegetation adjustment to present streamflow and sediment regimes will continue for a considerable period of time and that the new conditions will be significantly different than what may be considered “natural.”

The health and location of riparian vegetation along the Lower American River is dependent on streamflow and the set of interactions between channel form, process and recent history. In terms of these factors, the Lower American River is different from other “wild” streams in the Central Valley in that it is a confined stream, occupying a more narrow floodplain and stable channel. Thus, the LAR cannot freely change course by sediment erosion and deposition as other Central Valley Rivers like the Sacramento River.

Present trends in channel and riparian vegetation responses that are underway in the study reach include general flushing of stored sediments as well as channel degradation and widening due to influences from modern Folsom Dam, resulting in a generalized trend toward deeper channels with fewer gravel bars. Accelerated levels of channel scour and subsequent downstream channel instability are likely as well. (Watson 1985)

While the existing RCMP recommendations outlined above are well-considered and critical to riparian and aquatic habitat restoration, they include little to no specificity for how the goals are to be implemented. Furthermore, they do not adequately address the problem of flood control, drought and recreation on the Lower American River. An effective management strategy for the LAR must first begin with a prognosis of future conditions on the LAR along with upcoming challenges faced by the humans, wildlife and vegetation that depend on it for survival. To predict possible future conditions of the LAR, the selected site for this study will be addressed within the context of: 1) changing riparian and aquatic habitat conditions resulting from present and past human influence, 2) increased presence of flooding and drought from climate change, 3) aging levee and dam infrastructure, 4) increased water demand from urbanization and 5) increased recreation on the Parkway.

Changing riparian and aquatic habitat The riparian corridor and channel of the Lower American River is a dynamic and ever-changing system. In addition to natural forces such as geology and climate, human alterations outlined in

The US Fish and Wildlife Service (USFWS) has predicted that approximately 50% of existing forested area along the LAR will be lost over the next 100 years due to changes in hydrologic conditions, the deepening river channel, and drier conditions at the higher bank elevations.

The implications to general riparian conditions include a slight reduction of frequency and magnitude of peak flood flows and channel bed lowering. These effects should combine to impart a trend toward reduced frequency and severity of overbank flows on the various terraces of the corridor. (Water Forum 2005)

All these factors contribute to a gradual conversion of riparian forest to habitats dominated by more drought-tolerant upland species. This should in turn impart a trend toward reduced development of single aged cottonwood stands on higher terraces and an increased development of oak woodland on lower terraces. The shift in seasonal snowmelt runoff recession toward late summer should further reduce the rate at which cottonwood and willow regenerate by seed germination on fresh in-channel sediment deposits. Cottonwoods in particular are declining, as mature trees die of old age or fire damage and these trees are typically not replaced naturally. (Water Forum 2005)

With reduced frequency of seasonal flooding, the riparian forest is slower to regenerate, and some vegetation communities along the river have gradually changed to habitats that provide less value to wildlife and fish. One particular species of concern in the LAR is the Valley Elderberry Longhorn Beetle (VELB) that depends on elderberry shrubs for survival. In 1984, the VELB was listed as threatened under the Endangered Species Act with habitat loss cited as the reason for its decline. The USFWS called for the preservation of remaining VELB habitat and, if habitat loss is unavoidable, the replacement of lost habitat with mitigation.

Non-native, invasive plants also are a major concern in the LAR because they are likely to take over natural habitats along the river previously occupied by native species. In particular, Red Sesbania, Chinese Tallow tree, Giant Reed (arundo), Spanish Broom,

Tamarisk, and Black Locust are rapidly spreading in parts of the LAR. (Water Forum 2005) These species are able to out compete native plants such as willow and cottonwood and do not provide similar habitat value for fish and wildlife.

Climate ChangeChanging climate has disturbed weather all over the globe and the Lower American River is no exception. California will continue to be gripped by the paradoxical challenge of both extreme drought as well as increasing flood risk. Although droughts and floods are generally thought of as opposites, they can occur simultaneously as droughts tend to be long and cumulative while floods are generally short-lived and episodic (Lewis 2014).

As shown by figure 27 , several portions of the state of California have received more than 20 inches (508 mm) of precipitation in the first two weeks of December 2014. But as experts are quick to point out, the state remains locked in a historic drought. According to a Stanford Report in December 2014, the rains experienced thus far have brought only “short-term respite” to the on-going water crisis. As explained by Stanford University’s Daniel Swain:

During the past three years of drought, most of California has accumulated a precipitation deficit equivalent to one to two years of rain. Those are very large numbers, and it’s hard to make that back quickly. Even if you do get a particularly wet winter, you’d need to have record rainfall to break the drought, which would bring its own problems, such as flooding. (Swain)

Drought

Over the past three years, California has experienced a particularly deep drought. Future droughts in California are likely to worsen and last longer than the one now gripping the state, according to new research into the potential effects of climate change. (Weiser 2014). Scientists from the Scripps Institution of Oceanography and the U.S. Geological Survey used computer climate modeling tools to estimate the effects of warmer temperatures in future decades. The results show that by 2050, the median snowpack present on April

Fig. 26 U.S. Drought Monitor from Dec. 9, 2014 by NOAA/NWS/INCEPhttp://droughtmonitor.unl.edu/Home/RegionalDroughtMonitor.aspx?west

1 each year could be one-third smaller than the historical median, and by 2100 it could be two-thirds smaller. Such a dramatic loss of snowmelt would produce less runoff to refill reservoirs each summer, potentially making droughts an ever-present condition.

Flood

According to the Sacramento Area Flood Control Agency (SAFCA), Sacramento’s flood risk is the greatest of any major city in the country, including New Orleans. (SAFCA Website 2012). Some areas of Sacramento could flood more than 15 feet deep in the event of levee failure (City of Sacramento Dept. of Utilities). In the Central Valley at large, some communities could experience flood depths of over 20 feet. (Galloway, 2007)

Protection for many Central Valley communities is designed to achieve a “100-year” level of protection, which theoretically protects against floods that have a 1% probability of occurring in any given year. The probability of inundation from floods larger than the 100-year flood, however, is already 26% over 30 years, and is likely to increase with rising temperatures and precipitation. (Wilkinson et al, 2008) Much of the current flood management system is not designed to accommodate the larger and more frequent floods projected.

The extensive levees along the LAR, built in the early 1900s are widely regarded as aging and unreliable (Galloway). The American Society of Civil Engineers assigned the California levee system a grade of “D” on its most recent 2012 report card, up from a grade of “F” in 2006 (California Infrastructure Report Card)

Flood-induced economic damage and loss of life increase with depth of flood inundation and reduction of warning time (S.N. Jonkman, 2008). More intense, less predictable stream runoff, possibly exceeding the capacity of current levee design standards, may lead to a significant increase in flood-induced deaths and economic damage.

Furthermore, the construction of levees in rural at-risk zones continues to encourage urban development in hazardous areas (Tobin 1995). The National Flood Insurance Program permits dense urban development in flood prone zones which are “protected” by 100-year FEMA-certified levees. As the probability and severity of flooding increase with climate change, these newly urbanized areas may face increased risk.

Fig. 27 California 14 Day Observed Precipitation. 12/1/2014 - 12/14/2014http://water.weater.gov/precip/

Increased Water DemandThe LAR is an important source of drinking water. Each year, water suppliers divert water from Folsom Reservoir, Lake Natoma, and the LAR for municipal and industrial uses. The increased surface water diversions of the Water Forum Agreement recognizes that diversions from the LAR (including Folsom Reservoir) will increase in the future to support economic development and planned urban growth through the year 2030, even with active conservation programs and the sustainable use of groundwater (Water Forum 2005). It is estimated that American River diversions by purveyors will increase from the current level of 216,500 acre-feet annually to about 481,000 acre feet annually by the year 2030 (Water Forum 2005). Diversions at these levels could adversely affect the fishery, wildlife, recreational, and aesthetic values of the LAR.

Increased RecreationAs described in the Recreation chapter of this assessment, the lower American River contains a recreation and open space greenbelt that meanders 23 miles through the Sacramento urban area. The presence and size of this greenbelt in a metropolitan area is unique in the United States. The importance of this feature is reflected in recreation use intensity. The American River Parkway has approximately 5,520,000 user-days annually, which is greater than either Yellowstone or Yosemite National Parks (Gold 1985). As the region grows and land uses adjacent to the Parkway become more densely developed, there will be even greater numbers of Parkway users. Increased use could lead to detrimental impacts upon the natural resources and a less satisfying recreational experience. Potential impacts associated with overuse can be reduced or avoided by implementing management actions.

Alternative Strategies

It is evident that this reach of the Lower American River will experience many changes and challenges ahead. At a time in which the LAR is experiencing loss of riparian and aquatic habitats, channel degradation and levee/dam failure, LAR managers must further grapple with escalating flood and drought events along with increased water demand and intensified recreational activity. As a designated “wild and scenic river” within an urban context, the LAR must be managed to sustain and enhance environmental vitality and recreational uses without compromising its role as a flood-control system.

Increased reservoir storage on the river is one way to reduce the magnitude of peak discharge by spreading the flow over a longer time period (Leopold, 1968). This storage can take on many forms. The following alternatives for flood control will be assessed for their ability to maintain and if possible, enhance aquatic, riparian and recreational resources of the LAR.

No ActionThe effects of no action on the LAR can be analyzed as a baseline in which to compare alternatives. If no action is taken to mitigate the effects of climate change, environmental degradation and increased parkway use, the LAR will fail to serve its purpose as a flood control system and surrounding habitat would continue to worsen. The levees and dams would eventually fail and the surrounding urban development would be susceptible to increased flooding. On the other hand, if levees, dams and other hard infrastructure continue to be constructed without considering environmental effects, the American River Parkway would no longer support important habitat for resident migratory and wildlife species. In addition, the LAR would become a sterile, unwelcoming and unattractive area for residents and visitors alike, decreasing residential and commercial value along the area

Hard InfrastructureFlood detention facility at Auburn

A flood detention facility on the North Fork of the American River – east of the town of Auburn, California was proposed by the U.S. Bureau of Reclamation and slated to be completed in the 1970s. Straddling a gorge downstream of the confluence of the North and Middle Forks of the American River and upstream of Folsom Lake, it would have regulated water flow and provided flood control in the American River Basin. Following a nearby earthquake and discovery of a seismic fault beneath the dam site, the project was halted and for fear that the dam’s thin-arch design would not survive a major earthquake. Although the dam was redesigned, escalating costs and limited water storage offered by the design put an end to the project and the dam was never built.

In 1999 Congress granted Sacramento $285 million for new flood control measures but mainly to increase the size of the river outlets in the Folsom Sam and equalize the height of the levees on both sides of the American River. The Auburn Dam was not included in these measures.

This reliance on levees over flood retention could be a mistake. The Corps of Engineers warned in 1991 that, “For highly urbanized areas such as Sacramento, a flood control detention facility is preferred over levees. Reliance on high levees for flood protection in Sacramento is considered inherently less safe than an upstream detention dam.” Furthermore, a Corp study found the effects of the Auburn flood control detention facility on fish and wildlife to be significantly less than increasing levees along the river. (American River Watershed Investigation. 1988). Furthermore, much of the vegetation in the area has some flood tolerance – further reducing any environmental impacts of this strategy.

Increase flood control storage at Folsom Dam

Another alternative is to increase flood control storage at Folsom and as well as lowering the spillway. Both Folsom reservoir fisheries and downstream fisheries would suffer some adverse impacts from this alternative. However there would be relatively minor impacts to downstream riparian habitats and endangered species.

Levee restoration and improvements

As described in the flooding chapter of this assessment, this reach of the LAR is extensively fortified by levees extending from the mouth of the river to about 13 miles to the east. These levees are maintained by the Army Corps of Engineers who have a national policy that requires the removal of all woody vegetation over 2 inches in diameter.

On April 15, 2010, the California Department of Water Resources (DWR) and the California Department of Fish and Game (DFG) submitted extensive comments to the Army Corps asserting that, “The proposed vegetation policy will likely have devastating environmental impacts, as the remnants of the once cast riparian forests and adjacent riverine ecosystems of the Central Valley are now concentrated on the banks and levees of its flood channels. The proposed policy would greatly contribute to those cumulative losses and could result in the removal of mitigation vegetation planted in association with earlier flood management projects.” The letter goes on to elaborate on the preponderance of evidence that suggests that well-managed vegetation poses very little risk to Levee integrity and furthermore often improves public safety by reducing the potential for levee erosion. They state, “Tree growth, especially on the lower portions of the levees in the native banks or waterside slope, often has beneficial effects, including the stabilization of levee materials, the reduction of erosive forces and the slowing of higher flows, which in turn encourages the deposition of sediments.”

The detrimental effects of the Corps’ vegetation policy on the LAR can be alleviated by halting the removal of vegetation on levees and in many cases, even restoring vegetation to foster a healthier riparian habitat along and on levees of the LAR.

Natural MeasuresLong before Sacramento was developed, the Lower American River often flooded regularly. These floods cleared streams of debris and silt flowed from the streambeds to adjacent land, replenishing nutrients in the soil. Rather than a disaster, these floods benefited the environment. As demonstrated in the river assessment, flooding in the LAR has become heavily restricted in an effort to protect the multitude of homes and commercial buildings constructed on lands that had flooded for eons. For the most part, this flood protection has been in the form of stream channelization, levees, dams and hard infrastructure.

Numerous methods exist however that incorporates natural functionality with modern technology and design. Crib-Walls, floodway bypass channels and constructed wetlands are just a few alternatives presented here that can improve the LAR’s capacity for flood water while minimizing impacts to the ecosystem.

Live Cribwalls

Live cribwalls are chambers made of untreated, interlocking timbers or logs which are filled with alternating layers of soil and live branches above the stream’s base flow level. The cutting will sprout and develop a root mass that, in conjunction with the log structure will armor the stream bank and protect it from erosion. With time, the logs naturally degrade and the vegetation becomes the structure itself. As the live crib wall develops, it becomes a natural part of the riparian corridor and the submerged rocks and logs further provide excellent aquatic habitat. (Ohio Stream Management Guide)

As described in earlier chapters, stream bank incision is a prevalent and severe throughout the majority of this reach of study. Live cribwalls are an alternative that could be used to stabilize this slope and protect the bank from further degradation. Furthermore, vegetation not only improves the strength of the wall and the overall aesthetics of the site, it also creates fosters aquatic and riparian habitat.

Two areas on the study reach in particular could benefit from live cribwalls. The high berm described in the Woodlake Area that causes fish stranding can be reinforced with live cribwalls that would help restore the very degraded habitat in that area. In addition, the left bank of Cal Expo currently covered by sterile riprap could be replaced with crib walls that not only serves the same purpose as the rip rap but provide further ecological benefits.

Floodplain Bypass Channel

Constructing a bypass channel could provide an alternate channel for the LAR to use at certain flow levels to increase its discharge capacity in times of flooding. A variety of flood bypass systems exist. While an underground bypass tunnel or highly engineered bypass channel would increase flood capacity, neither provides aesthetic, recreational or environmental value to the region. A natural channel bypass would provide ecological benefits but would not generate enough flood capacity to be worthwhile. A complete reconnection to the floodplain on the other hand would be impossible given the proximity of the Sacramento urban development. Our recommendation therefore would be to create a floodplain bypass channel to diverge floodwaters into a constructed floodway for temporary storage.

The Yolo bypass in the upstream Sacramento Delta is a successful case study that could inform a bypass channel on the lower reach of the LAR. Constructed in the early 1930;s the Yolo Bypass conveys floodwaters for the Sacramento and Feather Rivers. As soon as the combined flow from the two rivers reach a critical level, the water is diverted to the Yolo Bypass. While the maximum flow capacity for the main channel of the Sacramento River is 110,000 cts, the Yolo Bypass can convey 490,000 cfs. While the Sacramento River has exceeded its flow capacity every year on average from 1956 to 1998, the Yolo Bypass has yet to exceed its capacity. In addition to its flood management benefits, the bypass and area wetlands serve as critical habitat for aquatic and riparian species.

A possible location for a floodway bypass on this reach of the LAR could be in the Bushy Lake area where it is far enough east of Sacramento to do some good but not all the way in Paradise Beach where there is not enough space to accommodate a constructed floodway. Furthermore, that area of the Cal Expo Subreach already supports seasonal wetland communities so increased flood inundation would not require much adaptation.

Constructed Wetlands

Like floodplain bypasses, constructed wetlands take advantage of the river’s natural ability to regulate excessive discharge. Wetlands are transition zones between uplands and deeper water and function as natural reservoirs that store floodwaters that overflow riverbanks and surface water that collects. In this way, wetlands can help protect adjacent and downstream property from flood damage.

The effectiveness of wetlands for flood abatement may vary, depending on the size of the area, type and condition of vegetation, slope, location of the wetland in the flood path and the saturation of wetland soils before flooding. A one-acre wetland can typically store about three-acre feet of water, or one million gallons. An acre-foot is one acre of land, about three-quarters the size of a football field, covered one foot deep in water. Three acre-feet describes the same area of land covered by three feet of water. Trees and other wetland vegetation help slow the speed of flood waters. This action, combined with water storage, can actually lower flood heights and reduce the water’s destructive potential. (Source: EPA)

Wetland habitats could be constructed in Discovery Park to convert the steep shorelines into a graded and contoured banks designed to flood seasonally. These wetlands should be designed with features that will develop into successful riparian habitats that support wildlife, control erosion and serve as floodplain habitat for out-migrating salmon.

Housing/Business relocationPrivate properties along the LAR severely limit river, vegetation and wildlife management, while limiting recreation and aesthetic value. By acquiring these properties, the city of Sacramento would have the ability to implement natural flood control measures that give the LAR room to flood and revegetate.

The two private properties in Discovery Park East – the Riverdale mobile home park and Camp Pollock (a boy scouts of America camping site) in particular seem like ideal areas for purchase and naturalization. Not only would this provide new riparian habitats along the LAR, but it would generate increased shade for aquatic communities. Furthermore, increased vegetation would improve water pollution by creating a buffer between urban runoff and the LAR.

Conclusion

The alternatives proposed here all have their individual advantages and disadvantages. While taking no action was considered for baseline analysis purposes, it is not a viable option as it does not achieve any of the goals or objects of this assessment. Taking a hard infrastructure approach to managing the LAR through measures such as dam and levee construction would bolster flood protection for Sacramento and surrounding urban areas but at the expense of environmental and recreational degradation. More natural methods such as live cribwalls, floodway bypasses and constructed wetlands would restore valued wildlife and aquatic habitats along the LAR but would be met with logistical obstacles such as increased cost and land ownership disputes. Relocating residential and commercial development along the LAR would further exacerbate these obstacles.

The proposed alternatives should not be seen as in competition with each other but rather tools that can be leveraged together to successfully manage the LAR. Hard infrastructure such as dams and levees will be inevitable in areas in close proximity to expensive urban development. Measures such as increased levee vegetation however can help mitigate their negative effects. Natural measures such as cribwalls and bypass channels can help reduce the need for such engineered infrastructure. Purchasing select private property along the LAR could further allow room for more restoration of the LAR by reconnecting it to its riparian habitat and floodplain.

The LAR will most likely never be completely returned to its original pristine state but by carefully considering future river management efforts, the infrastructure necessary for meeting human needs can be maintained while also creating environmental services that will benefit wildlife, vegetation and recreational users.

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