Minnehaha Creek Subwatershed Plan

Minnehaha Creek Watershed District Water Resources Management Plan

April 2007

Table Of Contents

1.0 INTRODUCTION AND SUMMARY...... 1 2.0 LAND AND WATER RESOURCES INVENTORY ...... 2 2.1 Location ...... 2 2.2 Physical Environment ...... 2 2.2.1 Topography and Drainage...... 2 2.2.2 Geology and Soils...... 2 2.2.3 Unique Features and Scenic Areas ...... 3 2.3 Biological Environment...... 3 2.3.1 Vegetation...... 3 2.3.2 Biologic Integrity...... 6 2.4 Human Environment...... 8 2.4.1 Present Land Use ...... 8 2.4.2 2020 and 2030 Land Use Planning ...... 8 2.4.3 Aquatic Recreation...... 8 2.5 Hydrologic Systems...... 18 2.5.1 Lakes...... 19 2.5.2 Streams...... 21 2.5.3 Ditches ...... 23 2.5.4 Wetlands ...... 24 2.5.5 Floodplain ...... 31 2.5.6 Groundwater ...... 31 3.0 PROBLEMS AND ISSUES ...... 35 3.1 Water Quality...... 35 3.2 Water Quantity...... 36 3.3 Wetlands ...... 36 3.4 Ecological Integrity...... 37 3.5 Groundwater ...... 37 3.6 Impacts of Future Growth...... 38 4.0 RESOURCE MANAGEMENT GOALS AND STRATEGIES...... 41 4.1 Infiltration/Filtration ...... 41 4.2 Ecological Integrity...... 43 4.3 Water Quality...... 46 4.4 Public Health...... 48

4.5 Water Quantity ...... 49 4.6 Shorelines and Streambanks ...... 52 4.7 Navigation ...... 54 4.8 Best Management Practices ...... 55 4.9 Education and Communications ...... 56 4.10 Ditches ...... 57 4.11 Wetlands ...... 58 4.12 Groundwater ...... 59 4.13 Floodplains ...... 61 4.14 Recreation ...... 62 4.15 Erosion Control ...... 63 4.16 Regulation ...... 65 4.17 Public Involvement ...... 66 5.0 IMPLEMENTATION PROGRAM ...... 69 5.1 Regulatory Program ...... 69 5.2 Land Conservation Program ...... 70 5.3 Education Program...... 70 5.4 Monitoring and Data Collection ...... 71 5.5 Operations and Maintenance...... 71 5.6 LGU Requirements ...... 72 5.6.1 Local Government Unit Subwatershed Phosphorus Load Reductions ...... 72 5.6.2 Land Conservation ...... 73 5.6.3 Other Issues ...... 73 5.7 Phosphorus Load Reduction ...... 73 5.8 Capital Improvement Program ...... 79 5.8.1 Minnehaha Creek Diagnostic Study/TMDL ...... 80 5.8.2 Minnehaha Creek Stream Restoration ...... 81 5.8.3 Minnehaha Falls/ Glen Restoration ...... 87 5.8.4 Lake Nokomis Internal Load Management ...... 87 5.8.5 Regional Volume and Load Reducation ...... 88 5.8.6 Land Conservation ...... 92 5.8.7 Browndale Dam Scour Repair ...... 93 5.8.8 Maintenance Projects ...... 94 5.8.9 Other Projects...... 94 5.8.10 Taft-Legion Lake Regional Volume and Load Reduction……………………….97-a 5.9 Summary ...... 97

TABLES

Table 1. Rare species in the Minnehaha Creek subwatershed...... 6 Table 2. DNR fish survey data...... 6 Table 3. Percent of Minnehaha Creek subwatershed by 2000 land use...... 8 Table 4. Public Waters in the Minnehaha Creek subwatershed...... 18 Table 5. Modeled peak discharge from the Minnehaha Creek subwatershed (cfs)...... 19 Table 6. Physical characteristics of lakes in the Minnehaha Creek subwatershed...... 19 Table 7. Selected water quality goals and current conditions of lakes in the Minnehaha Creek subwatershed...... 20 Table 8. Previous projects to improve water quality in Minnehaha Creek subwatershed lakes.. 20 Table 9. National Wetlands Inventory wetlands in the Minnehaha Creek subwatershed...... 24 Table 10. Dominant wetland type in the Minnehaha Creek subwatershed as assessed in the Functional Assessment of Wetlands...... 25 Table 11. Wetland management classifications of wetlands in the Minnehaha Creek subwatershed as determined in the Functional Assessment of Wetlands...... 25 Table 12. Modeled 2020 and ultimate development water quality and the total phosphorus loading reduction necessary to achieve in-lake total phosphorus concentration goals. 38 Table 13. Modeled annual volume of runoff in the Minnehaha Creek subwatershed, and estimated reductions resulting from application of a proposed 1” abstraction rule for new development and redevelopment (acre-feet)...... 50 Table 14. Ongoing District operations and maintenance tasks in the Minnehaha Creek subwatershed...... 71 Table 15. Ongoing District operations and maintenance tasks for the Minnehaha Creek subwatershed canoe facilities...... 71 Table 16. Ongoing District operations and maintenance tasks for previously completed Minnehaha Creek subwatershed improvement projects...... 72 Table 17. Potential ongoing operations and maintenance tasks for proposed Minnehaha Creek subwatershed improvement projects...... 72 Table 18. Allocation of Minnehaha Creek subwatershed general small-scale infiltration practices load from lakes TMDL as LGU Phosphorus Load Reductions (lbs/yr)...... 73 Table 19. Phosphorus load reduction plan for Lake Harriet (Goal = 20 μg/L)...... 75 Table 20. Phosphorus load reduction plan for Lake Nokomis (Goal = 50 μg/L)...... 76 Table 21. Phosphorus load reduction plan for Lake Hiawatha (Interim Goal = 61 μg/L)...... 77 Table 22. Phosphorus load reduction plan for Diamond Lake (Interim Goal = 90 μg/L)...... 78 Table 23. Phosphorus load reduction plan for Powderhorn Lake(Interim Goal = 90 μg/L)...... 79 Table 24. Estimated pond maintenance costs in the Minnehaha Creek subwatershed...... 94 Table 25. Problems and issues identified in the Minnehaha Creek subwatershed and actions proposed to address them...... 98 Table 26. Summary of metrics to be used in evaluating progress toward Minnehaha Creek subwatershed goals...... 105 Table 27. Summary of Minnehaha Creek subwatershed implementation program...... 107

FIGURES

Figure 1. Minnehaha Creek Subwatershed Location...... 4 Figure 1. Minnehaha Creek Subwatershed Drainage Areas...... 5

Figure 2. Minnehaha Creek Subwatershed Soil Hydrologic Groups...... 9 Figure 3. Minnehaha Creek Subwatershed Hydric Soils...... 10 Figure 4a. Minnehaha Creek Subwatershed MLCCS Land Cover: Imperviousness...... 11 Figure 5b. Minnehaha Creek Subwatershed MLCCS Land Cover: Cover Type...... 12 Figure 6. Minnehaha Creek Subwatershed Natural Resource and Recreation Areas...... 13 Figure 7. Minnehaha Creek Subwatershed 2000 Land Use...... 14 Figure 8. Minnehaha Creek Subwatershed 2020 Land Use...... 15 Figure 9. Minnehaha Creek Subwatershed 2030 Planning Framework...... 16 Figure 10. Minnehaha Creek Subwatershed Public Waters...... 17 Figure 11. Minnehaha Creek Subwatershed FAW Wetland Type...... 26 Figure 12. Minnehaha Creek Subwatershed FAW Wetlands...... 27 Figure 13. Minnehaha Creek Subwatershed High Habitat Value Wetlands...... 28 Figure 14. Minnehaha Creek Subwatershed Wetland Restoration Potential...... 29 Figure 15. Minnehaha Creek Subwatershed Floodplain...... 30 Figure 16. Minnehaha Creek Subwatershed Soil Infiltration Potential...... 32 Figure 17. Minnehaha Creek Subwatershed Aquifer Sensitivity...... 33 Figure 18. Minnehaha Creek Subwatershed Wellhead Protection Areas...... 34 Figure 19. Minnehaha Creek Subwatershed Key Conservation Areas...... 67 Figure 20. Minnehaha Creek Subwatershed Implementation Plan...... 102

1.0 Introduction and Summary

The Minnehaha Creek subwatershed encompasses all the Minnehaha Creek Watershed District (MCWD or District) downstream of the Grays Bay dam, and is commonly referred to as the “lower watershed.” The cities of Plymouth, Wayzata, Minnetonka, St. Louis Park, Hopkins, Edina, Minneapolis, and Richfield have land within this subwatershed. The subwatershed is drained by the 22-mile long Minnehaha Creek, which outlets to the Mississippi River in Minnehaha Falls Park. The central subwatershed is drained by the Minneapolis Chain of Lakes that includes Brownie, Cedar, Lake of the Isles, Calhoun, and Harriet. Other major lakes in the subwatershed include Nokomis, Hiawatha, Diamond, and Powderhorn. Several other smaller lakes and wetlands dot the subwatershed.

While some of the lakes meet or nearly meet their water quality goals, six lakes have been designated Impaired Waters for excess nutrients. Total Maximum Daily Load (TMDL) studies are currently underway to diagnose the source of those excess nutrients and to prepare an implementation plan for reducing nutrient loading and achieving water quality goals. Water quality in Minnehaha Creek is about average for the ecoregion, although it too has been designated an Impaired Water for its impaired fish community. The Chain of Lakes and the Creek are regional recreational and water resources. Several high-value wetlands are present in the subwatershed. Springs and seeps abound in the Mississippi Gorge area, including the high- value groundwater resource Camp Coldwater spring.

Over the next ten years, the District’s focus in the Minnehaha Creek subwatershed will be on: • Improving water quality in lakes that are currently impaired and preventing future water quality degradation. • Restoring ecological integrity in Minnehaha Creek through streambank restoration, habitat improvement, improved quality, and more stable flows. • Addressing existing streambank erosion and preventing future erosion.

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2.0 Land and Water Resources Inventory

2.1 Location

The Minnehaha Creek subwatershed encompasses all the MCWD downstream of the Grays Bay dam, and is commonly referred to as the “lower watershed” The cities of Plymouth, Wayzata, Minnetonka, St. Louis Park, Hopkins, Edina, Minneapolis, and Richfield have land within this subwatershed (see Figure 1). The Minnehaha Creek subwatershed is 30,290 acres in size (47.3 square miles).

2.2 Physical Environment

2.2.1 Topography and Drainage

The lower portion of this subwatershed generally east of the city of Hopkins is located within the Mississippi Valley Outwash region, which is typified by gently rolling terraces and bottom lands punctuated by small lakes formed from melted blocks of glacial ice. The upper portion of this subwatershed is located within the Emmons-Faribault moraine region, an area characterized by gently rolling to steep hilly landscapes with numerous lakes formed in deep irregular depressions called “kettles.”

The 2003 MCWD Hydrologic, Hydraulic, and Pollutant Loading Study (HHPLS) subdivided the Minnehaha Creek subwatershed into 184 subwatershed units, designated MC-1 through MC-184 (see Figure 2). Minnehaha Creek is formed at the outlet of Grays Bay and flows 22 miles to the Mississippi River. The Chain of Lakes in the City of Minneapolis (Brownie, Cedar, Isles, Calhoun, Harriet) drain parts of Minneapolis and St. Louis Park and discharge to Minnehaha Creek. Lake Hiawatha is located in-line to Minnehaha Creek and is heavily influenced by it.

2.2.2 Geology and Soils

The depth to bedrock within the subwatershed varies from 100-200 feet in the upper subwatershed to 0-100 feet in the lower subwatershed near the Mississippi River. In the upper subwatershed, quaternary deposits – the surficial material overlaying the bedrock - are generally high relief New Ulm loamy till, with pockets of peat and muck and glacial outwash along the Minnehaha Creek corridor. In the lower subwatershed, glacial outwash overlays the bedrock with pockets of peat and muck. Glacial drift deposits up to 300 feet thick lie in the buried bedrock valley under the area near Lakes Calhoun and Harriet. At Minnehaha Falls and the Mississippi River the glacial drift has eroded away, exposing bedrock.

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Soils within the watershed are predominantly urban disturbed soils that have not been classified. The HHPLS assumed that Urban Disturbed soils were primarily classified as Natural Resources Conservation Service Hydrologic Soil Group B soils. Where the soils have been classified, they are mainly Group B (loamy soils with moderate infiltration potential) and D (clayey soils with very low infiltration potential) (see Figure 3). The Group D soils are found in low-lying areas and are generally hydric, or showing indications of inundation (see Figure 4) or are in areas of mucky soils. There are also scattered areas of Group A soils, sandy loam soils with high to moderate infiltration potential.

2.2.3 Unique Features and Scenic Areas

The subwatershed contains numerous regional recreational facilities. The National Park Service oversees the Mississippi National River and Recreational Area, which includes the Mississippi River gorge area within the subwatershed, including Minnehaha Falls. The Falls area includes a number of structures constructed by the Works Progress Administration (WPA), including retaining walls along the creek. The Minneapolis Park and Recreation Board (MPRB) operates a popular park and trail system around the Chain of Lakes and along Minnehaha Creek east of Lake Harriet. The North and South branches of the Three Rivers Park District’s Southwest LRT Regional Trail connects the Chain of Lakes with the western subwatershed.

Camp Coldwater Spring, a site with significance to Native American communities and the location of the first white settlement in Minnesota, is located in the extreme southeast part of the subwatershed. The Minnesota Historic Features database notes over 1300 historic features in this subwatershed, most residences or commercial buildings. Three Historic Districts are listed on the National Register of Historic Places: the Minnehaha District in the vicinity of Minnehaha Falls; the Nokomis Knolls District, a residential district at the southwest corner of Lake Nokomis; and the Country Club District in Edina, an area of over 500 historic residences, commercial buildings, and other properties, including the Minnehaha Grange. More detail regarding Camp Coldwater Spring and other locations significant to the watershed’s early history can be found in the Water Resources Management Plan.

2.3 Biological Environment

2.3.1 Vegetation

Land cover as classified by the Minnesota Land Cover Classification System (MLCCS) is shown on Figure 5. Urban areas with moderate to high densities of impervious surface characterize the subwatershed, which is entirely developed. There are some sizable areas of wetland and forest/woodland in the city of Minnetonka and in some locations along the creek corridor. An extensive but narrow park system surrounds the Minneapolis lakes and Minnehaha Creek and along the Mississippi River.

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2.3.2 Biologic Integrity

Landscape. Development in this subwatershed has left few large areas of undisturbed or minimally disturbed forest and wetland in the subwatershed. Three areas, including the Grays Bay outlet wetland complex; Diamond Lake; and part of the creek corridor in the Mississippi River gorge have been designated Regionally Significant Ecological Areas by the DNR (see Figure 6). The Minnesota County Biological Survey (MCBS) did not identify any areas of biodiversity significance in the subwatershed. The creek corridor and the Chain of Lakes in the lower subwatershed are part of a DNR-designated Metro Conservation Corridor.

The Minnesota Natural Heritage Information System lists several rare species in this subwatershed, as shown in Table 1.

Table 1. Rare species in the Minnehaha Creek subwatershed. Species Status Acadian flycatcher State concern Biennial gaura Being evaluated Blanding’s turtle State threatened Lake sturgeon State concern Prairie vole State concern Pugnose shiner State concern Rock clubmoss State threatened Valerian State threatened Source: Minnesota DNR.

Lakes. The MPRB has prepared vegetation surveys for some of the Chain of Lakes, and has conducted phytoplankton and zooplankton surveys of those lakes. A vegetation survey compiled by the MPRB for Diamond Lake in 2004 indicated the presence of curly leaf pond weed on that lake. Most of the city lakes have been colonized by Eurasian watermilfoil.

The MPRB periodically harvests milfoil on Harriet, Calhoun, Lake of the Isles, Cedar, and Nokomis to support swimming and boating. Such harvesting was completed in 2004 on Harriet, Calhoun, Isles, and Cedar. In addition, the MPRB is working together with the University of Minnesota to explore the use of a native weevil to naturally control nuisance milfoil growth. Lakes treated include Calhoun, Hiawatha, Harriet, and Isles.

Fishery. Because of their status as regional resources, the Minnesota DNR conducts regular fish surveys of the Chain of Lakes. Other lakes are surveyed less frequently. Powderhorn Lake is managed by the DNR as part of its Fishing in the Neighborhood program and is stocked regularly with black crappie and bluegill and most recently with channel catfish.

Table 2. DNR fish survey data. Fishery – fish Lake Survey Year Dominant Fish stocked Brownie 1993 Pan Bluegill, black crappie Bluegill, black crappie, northern pike, yellow perch, Cedar 2003 Sport pumpkinseed sunfish, largemouth bass, muskellunge, walleye

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Fishery – fish Lake Survey Year Dominant Fish stocked Sport – Bluegill, black crappie, largemouth bass, northern Isles 2003 muskellunge pike, yellow perch Sport – walleye Bluegill, black crappie, northern pike, yellow perch, Calhoun 2003 and muskellunge pumpkinseed sunfish Sport – walleye Bluegill, black crappie, yellow perch, pumpkinseed Harriet 2003 and muskellunge sunfish Sport – walleye Nokomis 2001 Yellow perch, black crappie, bluegill and muskellunge Hiawatha 2001 Pan Black bullhead, black crappie, bluegill, yellow perch Diamond 1993 Black bullhead, carp, bluegill, green sunfish Pan – black Powderhorn 2003 crappie and Black crappie, bluegill, black bullhead bluegill Source: Minnesota DNR.

Streams. Minnehaha Creek has been listed on the State of Minnesota’s 303(d) list of Impaired Waters for its impaired biotic community. A fish survey was conducted at nine locations on Minnehaha Creek in 2003. Most of the fish species between I-494 and Minnehaha Falls were lake species with few adults, indicating a lack of suitable habitat for riverine species. Lack of adults indicates that there is little refuge for overwintering and low flow periods. Below the falls the creek is connected to the Mississippi River and there is better habitat for riverine species.

Macroinvertebrate sampling on Minnehaha Creek was conducted as a part of the 2004 MCWD Minnehaha Creek Stream Assessment. Twenty-six sites were sampled; only about half yielded more than the 100 organisms typically needed to assure a statistically valid score. An F-IBI score – an Index of Biotic Integrity identified to the organism’s family level – was calculated for thirteen reaches. Macroinvertebrate family diversity was very low, primarily due to habitat limitations and the influence of the various impoundments and wetlands through which the creek flows.

Aquatic habitat in Minnehaha Creek is generally poor. Stream substrates are homogenous and dominated by small gravels and sand, and gravel or cobble riffles are infrequent and widely spaced. Large woody debris is virtually absent, limiting direct use by macroinvertebrates and fish and reducing the number of accumulation points for leaf and other debris. Stream flows from Grays Bay dam discharge range from sustained high volumes and velocities to minimal or intermittent flows, creating undesirable conditions.

The low diversity of macroinvertebrates reflects the lack of diversity in habitat. Lack of riparian vegetation, erosion, sediment deposition, removal of large woody debris, sustained high flows, extreme flood peaks, lowered base flows, and to a lesser extent water quality combine to limit species diversity. See Section 2.5.2 below for additional discussion.

Wetlands. A high density of wetlands are present in the subwatershed. A number of wetlands were identified in the 2003 MCWD Functional Assessment of Wetlands (FAW) as having exceptional to high aesthetic values (see Figure 13). Wetlands riparian to and in-line with

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Minnehaha Creek as well as several wetlands adjacent to lakes were noted as having high fish habitat potential. Only a few of the larger wetlands were assessed as having high wildlife habitat potential, primarily because wetland size is an important factor. Only a scattering of wetlands were identified as having exceptional to high vegetative diversity, unsurprising given the urbanized nature of the subwatershed and the likelihood of wetland disturbance and hydrologic impacts.

2.4 Human Environment

2.4.1 Present Land Use

The predominant land use in the subwatershed is single family residential, followed by park and open space (see Figure 7 and Table 3). Most of the vacant land is large wetland or woodland tracts. The subwatershed is fully developed at typical urban and suburban densities and land uses.

Table 3. Percent of Minnehaha Creek subwatershed by 2000 land use. Land Use 2000 Acres % of Subwatershed Single - Family Residential 16,680.3 55.0% Parks and Open Space 3,877.9 12.8% Water 1,674.0 5.5% Vacant or Undetermined 1,660.8 5.5% Institutional 1,469.5 4.8% Commercial 1,443.7 4.8% Roads and Highways 1,422.8 4.7% Multi - Family Residential 1,133.0 3.7% Industrial 939.3 3.1% Agricultural - 0.0% 30,301.3 Source: Metropolitan Council. See Figure 7.

2.4.2 2020 and 2030 Land Use Planning

Because so much of the subwatershed is already developed, future land use in the subwatershed is not expected to change dramatically by 2020 or 2030 (see Figures 8 and 9), although there will be redevelopment. Redevelopment and infill development will provide opportunities to retrofit with stormwater quantity and quality measures in areas that currently have no measures or inadequate measures.

2.4.3 Aquatic Recreation

There are numerous boat accesses and beaches on the lakes in the subwatershed. There are seventeen canoe landings on Minnehaha Creek (see Figure 6). Most of these have parking available, and several have picnic areas and restrooms.

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2.5 Hydrologic Systems

The Department of Natural Resources’ Public Waters Inventory identifies 86 basins and three watercourses within the Minnehaha Creek subwatershed as under the jurisdiction of the DNR (see Figure 10). These include the Chain of Lakes; other named lakes, ponds, and marshes; and numerous unnamed basins, listed in Table 4.

Table 4. Public Waters in the Minnehaha Creek subwatershed. Name and Name and Name and Name and DNR ID# DNR ID# DNR ID# DNR ID# Bass (27-15 P) Mother (27-23 P) Unnamed (27-717 W) Unnamed (27-755 W) Brownie (27-38 P) Nokomis (27-19 P) Unnamed (27-718 P) Unnamed (27-756 P) Calhoun (27-31 P) Norby's Pond (27-685 W) Unnamed (27-719 P) Unnamed (27-757 W) Cargill Pond (27-754 W) Pamela Pond (27-675 P) Unnamed (27-720 W) Unnamed (27-758 W) Sanctuary Marsh (27-665 Cedar (27-39 P) P) Unnamed (27-721 P) Unnamed (27-759 W) Cemetery (27-17 P) Taft (27-683 P) Unnamed (27-722 W) Unnamed (27-762 W) Diamond (27-22 P) Twin (27-656 P) Unnamed (27-723 W) Unnamed (27-763 W) U.S. Lock & Dam #1 (27- Duck (27-25 P) 3 P) Unnamed (27-724 W) Unnamed (27-771 W) Edina Mill Pond (27-41 P) Unnamed (27-1087 W) Unnamed (27-725 W) Unnamed (27-772 W) Grays Bay Outlet (27-761 W) Unnamed (27-657 P) Unnamed (27-726 W) Unnamed (27-773 W) Hannan (27-52 P) Unnamed (27-658 W) Unnamed (27-728 W) Unnamed (27-774 W) Harriet (27-16 P) Unnamed (27-659 W) Unnamed (27-736 W) Unnamed (27-779 W) Harvey (27-670 W) Unnamed (27-660 P) Unnamed (27-737 W) Unnamed (27-780 W) Hiawatha (27-18 P) Unnamed (27-661 W) Unnamed (27-739 W) Unnamed (27-83 W) Unnamed (Cedar Manor) Lake of the Isles (27-40 P) Unnamed (27-662 W) Unnamed (27-740 W) (27-713 W) Lamplighter Park (27-710 Unnamed (Cobblecrest) P) Unnamed (27-663 W) Unnamed (27-741 W) (27-53 P) Unnamed (Westling Pond) Legion (27-24 P) Unnamed (27-666 W) Unnamed (27-748 W) (27-714 W) Meadowbrook (27-54 P) Unnamed (27-667 W) Unnamed (27-749 W) Victoria (27-51 P) Melody (27-669 W) Unnamed (27-682 W) Unnamed (27-750 W) Windsor (27-82 P) Milner Pond (27-684 W) Unnamed (27-712 W) Unnamed (27-751 W) Wolfe Park (27-664 P) Minnehaha Marsh (27-84 P) Unnamed (27-715 W) Unnamed (27-752 W) Minnehaha Creek Unnamed from Brownie Minnetonka (27-133 P) Unnamed (27-716 W) Unnamed (27-753 W) to Calhoun Unnamed from Harriet to Minnehaha Creek Source: Minnesota DNR. See Figure 10.

The HHPLS included detailed modeling of the current and 2020 hydraulic and hydrologic conditions in the subwatershed. That modeling includes the following results for modeled locations (lakes, ponds, channels, and crossings) within the subwatershed (see Table 5): ƒ Existing Normal Water Level; ƒ Existing High Water Level, peak discharge, and peak velocity for the 1.5 year, 24-hour and 100-year, 24-hour events; ƒ 2020 predicted HWL, peak discharge, and peak velocity for the 100-year, 24-hour event; and the

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ƒ Existing High Water Level for the 100-year, 10-day snowmelt event.

Those detailed results are not reproduced here, but are incorporated by reference. The HHPLS model predicted that land use changes would not significantly impact high water levels in the subwatershed. However, it was noted that overtopping of the creek banks can occur. Numerous land locked subwatershed units or small basins occur in the subwatershed, and management of discharge from those landlocked basins as well as from land use change is important to minimizing or preventing further streambank erosion.

Table 5. Modeled peak discharge from the Minnehaha Creek subwatershed (cfs). Event Existing 2020 Snowmelt 1.5 year, 24 hour 219.7 - - 100 year, 24 hour 676.2 677.9 - 100-year, 10-day - - 618.5 Source: 2003 MCWD Hydrologic, Hydraulic, and Pollutant Loading Study (HHPLS)

The HHPLS scour analysis identified nearly 120 locations along the creek as having high erosion potential based on soils and modeled velocity. The Stream Assessment included a geomorphologic analysis of creek stability as well as a detailed survey of the creek for sites actually experiencing erosion and streambank failure (see Section 2.5.2 below).

2.5.1 Lakes

The Minnehaha Creek subwatershed includes the Chain of Lakes in Minneapolis and several other smaller lakes. Powderhorn Lake in Minneapolis does not drain to the creek, but rather is pumped to the Mississippi River.

Table 6. Physical characteristics of lakes in the Minnehaha Creek subwatershed. Maximum Watershed to Lake DNR Lake Surface Area Depth Area Ratio Classification Brownie 12 20 20:1 Natural Environment Cedar 170 51 11:1 Recreational Development Isles 103 31 7:1 Recreational Development Calhoun 408 90 7:1 Recreational Development Harriet 353 82 3:1 Recreational Development Nokomis 204 33 4:1 Natural Environment Hiawatha 54 30 2145:1 Natural Environment Diamond 54 6 16:1 General Development Powderhorn 11 20 26:1 Natural Environment Source: Minnesota DNR.

Several of the lakes in this subwatershed are listed on the State of Minnesota’s 303(d) list of Impaired Waters. Six lakes are listed for excess nutrients, and the MCWD is preparing a Total Maximum Daily Load (TMDL) analysis for four of those lakes. Two lakes are proposed for de- listing – Brownie and Lake of the Isles. The TMDL will establish phosphorus load reductions and include an implementation plan that incorporates specific strategies to reduce phosphorus loading. Six lakes are listed for fish consumption impairment by mercury. The MPCA is preparing a region-wide TMDL for that contaminant.

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Table 7. Selected water quality goals and current conditions of lakes in the Minnehaha Creek subwatershed. 1997 HHPLS 1997-2004 Water 2004 Lake TP Goal TP Goal Average Quality TP Chl-a Secchi TSI (μg/L) (μg/L) TP (μg/L) Impairments (μg/L) (μg/L) (m) Nutrients Brownie 50 35 38 45 19 1.5 58 Mercury Cedar 50 25 22 Mercury 25 7 3.7 47 Nutrients Isles 50 40 40 50 28 1.8 58 Mercury Calhoun 30 25 24 Mercury 15 3 5.2 40 Harriet 30 20 23 Mercury 15 3 5.2 43 Nutrients Nokomis 50 50 59 Mercury 80 28 1.0 64 PCBs Hiawatha 50 50* 68 Nutrients 68 17 1.3 60 Diamond - 90 Nutrients 178 38 0.8 69 Powderhorn 90 120* Nutrients 118 37 0.7 68 *Hiawatha’s interim goal in the draft TMDL is 61 and Powderhorn’s is 90. Source: MCWD.

The MCWD and partners including the MPRB, City of St. Louis Park, City of Minneapolis, and Hennepin County have undertaken numerous projects in this subwatershed to improve water quality in the lakes. These include:

Table 8. Previous projects to improve water quality in Minnehaha Creek subwatershed lakes. Lake Year Project Purpose Brownie • None specific • 1995-96 • Twin Lakes Park • Increases storage capacity of Twin Lakes and treats Pond & Dredging water entering Twin Lake • Cedar Meadows • Treats water entering Cedar Lake Cedar • 1996-97 • Cedar Alum • Treats phosphorus in lake Treatment • Prevents rough fish migration from Cedar Lake to • 1998 • Fish Screen Cedar Meadows • 2004- • MPRB Isles • Shoreline stabilization, native plant restoration, wetland Isles present Renovation Plan enhancement and restoration • Three cell wet detention system to treat stormwater Calhoun • 1999 • Lake Calhoun Ponds prior to entering Lake Calhoun • Alum treatment • Increased street sweeping, additional grit chambers • 1994- • MPRB/Minneapolis Harriet (1994-96), constructed wetlands (1998), and littoral present BMPs alum treatment (2001) • Lake Nokomis • Three ponds to treat runoff, additional grit chambers, an Nokomis • 2001 Improvements inflatable weir at the outlet, rough fish removal Hiawatha • None specific • 60th Street & 1st • Alleviates flooding and treats stormwater discharging Diamond • 2000 Avenue Pond to Diamond Lake • 2001- • MPRB/City • Five continuous deflective separation grit chambers Powderhorn present Restoration Plan (2001), native plantings (2002), alum treatment (2003) Source: MCWD and Minneapolis Park and Recreation Board 2004 Water Resources Report

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2.5.2 Streams

Minnehaha Creek is the primary stream within the subwatershed. It is formed at the outlet of Grays Bay in Minnetonka and flows 22 miles to the Mississippi River. One lake, Lake Hiawatha, is in-line to the creek and heavily influenced by it.

As the outlet for Lake Minnetonka and the upper watershed, Minnehaha Creek must discharge large volumes of water during spring snowmelt runoff, summer and fall. During a typical year, 4-6 inches of runoff from the 122 square mile watershed tributary to the outlet are discharged to Minnehaha Creek. The typical average flow in the creek from this discharge is 60 to 90 cfs.

An operating plan was established for the Grays Bay dam headwaters control structure when it was put into service in 1980. The plan was intended to emulate the historical discharge hydrograph produced by previous controls and the natural outlet of Lake Minnetonka.

In drier periods Lake Minnetonka typically does not discharge water. Development in the lower watershed has changed subwatershed hydrology. Wetlands and depression storage that naturally extend the period of flow have been largely eliminated in the lower watershed. A large volume of surface runoff is produced by the impervious area but it is discharged over a short period of time, leaving the creek dry at times. It is also likely that development has decreased groundwater discharge to the creek so the base flow to the creek from that source has been diminished.

Stream Assessment. Minnehaha Creek was studied in-depth in 2003-4 as part of the District’s Minnehaha Creek Stream Assessment, which included a physical inventory, erosion survey, fluvial geomorphic assessment to determine channel stability, and a biological assessment.

Flow in the creek is controlled by numerous structures, including major weirs at the Grays Bay Dam outlet, the Browndale Dam, West 54th Street, and Hiawatha Avenue. There are more than 100 bridge crossings, many of which provide grade stabilization. Some of those crossings provide a grade control substantial enough to create an impoundment of hydraulically stagnant water upstream.

There are 178 identified storm sewer outfalls larger than eight inches in diameter along the length of the creek. Most of those outfalls are located downstream of the Browndale Dam in Edina and Minneapolis. Many are experiencing local bank erosion and scour. Eleven exposed utility crossings were identified along the creek, eight of which are in the city of Minneapolis.

Approximately 15 percent of the streambank is armored by concrete or masonry retaining walls, riprap, or other protection such as gabion baskets. These are generally for the purpose of controlling erosion and meandering to prevent loss of property, stabilizing steep banks, or protecting structures such as bridges and storm sewer outfalls. Many of these stream walls were presumably constructed by the Works Progress Administration (WPA) during or following the Great Depression.

The Stream Assessment identified 35 sites of significant erosion or bank failure - typically more than one to two feet in height - and lesser erosion damage and bank failures along much of the

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creek. Most of the significant failures were downstream of the Browndale Dam in the city of Minneapolis. Other significant features cataloged in the Stream Assessment include 26 sites with deltas and sandbars; 20 sites with small amounts of miscellaneous debris, 16 private docks, and numerous miscellaneous features such as islands, side channels, stairs, wetlands, inlet channels, and rock piles.

A fluvial geomorphic assessment was completed as part of the Stream Assessment to evaluate channel stability. In general the assessment determined that although erosion and incision has occurred in the creek, it now has a relatively stable channel profile because numerous bridge crossings and other structures will prevent further incising. However, the channel width is not stable in several locations and was observed to be expanding. Eighteen of the 30 reaches were assessed as stable, eight as stable with a tendency to aggrade or degrade, and six are aggrading (accumulating sediment). Aggradation is likely the result of the numerous vertical controls such as bridges that create impoundments.

Water Quality. Minnehaha Creek is included in the District’s Annual Hydrologic Data monitoring program. Water quality and flow in the creek is monitored at eight locations. Phosphorus and TSS concentrations in Minnehaha Creek are comparable to the North Central Hardwood Forest ecoregion mean, which is generally a result of the good quality of water discharged into the creek from Lake Minnetonka. In general nutrient and sediment loads increase upstream to downstream, although the impoundments at the major grade controls impact those concentrations. While the flow-weighted average chloride concentrations in the creek were lower than the state chronic standards of 230 ug/L, several individual grab samples did exceed that standard, although none exceeded the acute standard of 830 ug/L.

Grab samples from seven sites were tested for the presence of e. coli bacteria. While the acute standard was not violated in 2004 in the creek, the 30 day geometric mean standard was violated at five sites on the lower creek for the months of September and October 2004. In 2005 the District expanded the creek monitoring to additional sites and adjusted sampling frequency to assist in identifying the source or sources of e. coli. In addition, samples are being analyzed for traces of caffeine, which may indicate that human waste is one of the sources of e. coli. Results are pending. Dissolved oxygen was measured at eight locations and generally maintained levels greater than the 5 mg/L State of Minnesota standard for class 2B waters. Measurements did dip below the 5 mg/L standard periodically, depending on flow in the creek and on location relative to large riparian wetland complexes.

Biologic Integrity. Minnehaha Creek is listed on the State of Minnesota’s 303(d) list of Impaired Waters for impaired biotic integrity. The most limiting factor for the ecology of Minnehaha Creek is its variability of flow, which as noted above ranges from intensive periods of high volume and velocity flow to periods of low or no flow. During those latter periods much of the channel runs dry, leaving few pools or backwaters to serve as refuge for fish and macroinvertebrates. The creek also has a lack of physical complexity. The channel is mostly of relatively constant dimensions, has very small amounts of woody debris, and little variation in depth and slope. These factors severely limit opportunities for aquatic life to sustain viable populations. Section 2.3.2 above discusses stream biologic integrity more fully.

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Creek Visioning. The District in 2005 undertook a joint partnership with the United States Army Corps of Engineers to develop a large-scale, long-term Vision for Minnehaha Creek to serve as guidance for organizations that share Creek corridor management responsibilities. A Citizen Advisory Committee of community representatives and a Technical Advisory Committee of agency representatives through a lengthy community input process developed a common vision and management recommendations.

The 2005 MCWD Minnehaha Creek Visioning Partnership Final Report presents the results of that process and summarizes the Partnership’s recommendations for future Creek management. Erosion control and support of aquatic life were overall the highest ranked priorities for improvement. However, when considered reach by reach, support and maintenance of recreation were the highest priority for the reaches upstream of the Browndale dam, followed by improvement of aquatic life and erosion control. Erosion control and streambank stabilization was the highest priority for the reach downstream of the Browndale dam. The Partnership recommended the District consider bioengineered stabilization techniques over hard armoring where possible, and that habitat improvement be focused on the management of riparian vegetation and retention of large woody debris rather than on in-stream habitat management. The Partnership also recommended that water quality be improved through the reduction of peak stormwater flows; pretreatment of discharges; application of BMPs and good housekeeping practices in the subwatershed; and repair of existing erosion.

An important part of the visioning process was the discussion of several streamflow management scenarios developed by the Corps to model what would happen with changes to the operation of the Grays Bay dam. The dam is managed to discharge water from Lake Minnetonka into the Creek only when the DNR-established runout elevation of the lake is exceeded. During dry periods lake level falls and there is minimal discharge; flow in the creek falls to minimal flow- related aquatic habitat conditions and canoeing is not possible. The Corps developed a number of scenarios that would provide targeted releases for recreation or habitat purposes, and then modeled the resulting impact on water level in Lake Minnetonka; the percent of time creek flow fell within optimal conditions for aquatic habitat and recreation; the percent of time potentially erosive flows could be expected; and resulting estimated water quality. Each scenario attempted to balance these often competing interests; in the end the Partnership recommended that further study be completed to find a way to optimize and balance year round minimum flows and moderated extreme flows with recreational and lake uses.

2.5.3 Ditches

Three public drainage ditches established under Minnesota Statutes Chapter 103E are located within this subwatershed (see Figure 10). The purpose of the ditches was likely to drain wetlands to provide additional land for agriculture and development. These ditches have been converted to stormsewer and no longer provide that function today.

County Ditch #14. This ditch in St. Louis Park and Minneapolis was established prior to 1908 and originally connected a wetland northwest of Bass Lake to Bass Lake. It then outletted Bass Lake to the east and flowed to the southwest corner Lake Calhoun. It has largely been converted to storm sewer, but a portion of the ditch through the Minnekahda Golf Course remains an open

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channel along a similar alignment to the original. The area previously served by the ditch is now served by stormsewer, and the ditch no longer serves its original purpose.

County Ditch #17. County Ditch #17 was established in 1908 and was intended to drain a large wetland complex in St. Louis Park, Minneapolis, and Edina. The alignment extends from what is now the intersection of Morningside and Browndale to the outlet at Lake Calhoun around 37th Street. It has been entirely converted to storm sewer that does not follow the exact path of the ditch but generally receives drainage form the same area. These storm sewers were intercepted and diverted into the stormwater ponds constructed by the MCWD as part of the Southwest Lake Calhoun Ponds project. The area previously served by the ditch is now served by storm sewer, and the ditch no longer serves its original purpose.

County Ditch #29. This ditch in St. Louis Park begins at about Minnetonka Boulevard and Highway 100 and runs east to its terminus near the railroad tracks. The ditch has been completely converted to storm sewer which is for the most part located in the alignment of the former ditch. The area previously served by the ditch is now served by storm sewer, and the ditch no longer serves its original purpose.

2.5.4 Wetlands

Approximately 12 percent of the land area within the Minnehaha Creek subwatershed is shown on the National Wetland Inventory as wetland (see Table 9).

Table 9. National Wetlands Inventory wetlands in the Minnehaha Creek subwatershed. Area Circular 39 Type Area (acres) Cowardin Class (acres) Seasonal 43.8 Emergent 1,594.7 Wet Meadow 8.5 Forested 95.2 Shallow Marsh 1,546.9 Scrub Shrub 42.1 Deep Marsh 54.4 Unconsolidated Bottom 1,664.3 Open Water 1,570.7 Unconsolidated Shore 2.9 Scrub Shrub 42.1 Forested 89.9 Industrial Activity 2.3 Riverine 40.6 TOTAL 3,399.2 3,399.2 Source: Minnesota DNR.

In 2001-2003 the District undertook a Functional Assessment of Wetlands (FAW) on all wetlands greater than one-quarter acre in size. This assessment used a variant of the Minnesota Routine Assessment Method. In contrast to Table 9 above, which shows wetland acreage and type from the National Wetlands Inventory completed in the 1980s, Table 10 below shows the acreage and type as assessed in the field. Using the results of that analysis, individual wetlands were assigned to one of four categories – Preserve, and Manage 1, 2, or 3 (see Figure 12 and Table 11). Wetlands that were evaluated as Exceptional or High on certain ecological or hydrologic values were assigned to the Preserve category. The balance of evaluated wetlands were assigned to a category based on this assessment of current functions and values, with Manage 1 wetlands exhibiting higher values and Manage 2 and 3 moderate or lower values.

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Refer to the Functional Assessment of Wetlands (2003) for details of methodology, classification, and management recommendations.

Table 10. Dominant wetland type in the Minnehaha Creek subwatershed as assessed in the Functional Assessment of Wetlands. Circular 39 Type Area (acres) Seasonal 99.8 Wet Meadow 175.5 Shallow Marsh 772.6 Deep Marsh 28.8 Open Water 552.0 Scrub Shrub 432.0 Forested 418.5 Bogs 3.0 Lakes 1,347.9 Not typed 43.9 TOTAL 3,874.0 Note: Based on field assessment. Excludes those areas determined in the field not to be wetlands, and stormwater ponds clearly excavated out of upland. Includes some small areas that were not field assessed. Source: MCWD 2003 Functional Assessment of Wetlands. See Figure 11.

Table 11. Wetland management classifications of wetlands in the Minnehaha Creek subwatershed as determined in the Functional Assessment of Wetlands. Area Classification Number % of total (acres) Preserve 176 1,035.3 38.9% Manage 1 157 575.6 21.6 Manage 2 128 314.7 11.8 Manage 3 371 735.5 27.6 TOTAL 832 2,661.1 Note: The FAW excluded large lakes and wetlands less than ¼ acre in size; those areas are included in the NWI, so total will not match Tables 9 or 10. Source: MCWD 2003 Functional Assessment of Wetlands. See Figure 12.

The Minnehaha Creek subwatershed has a large number of wetlands of various sizes distributed across the landscape, including several very large wetlands and numerous wetlands through which the creek flows. Many scored highly on vegetative diversity, fish and wildlife habitat, or aesthetics (see Figure 13). Some of the wetlands were also evaluated for restoration potential. Factors considered were the ease with which the wetland could be restored, the number of landowners within the historic basin, the size of the potential restoration area, the potential for establishing buffer areas or water quality ponding, and the extent and type of hydrologic alteration. Only a few wetlands of moderate or high restoration potential are located throughout the subwatershed, and most of those are small (see Figure 14).

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2.5.5 Floodplain

Floodplain is shown on Figure 15. In 2005 the District completed an evaluation of flood elevations on Minnehaha Creek, and four upper watershed streams: Gleason Creek, Long Lake Creek, Painter Creek, and Six Mile Creek. Figure 15 shows the elevations of floodplains modeled by the District and other floodplains in the subwatershed.

2.5.6 Groundwater

There are a number of springs and seeps in the Mississippi River gorge area, including Camp Coldwater Spring, the largest limestone bedrock spring in the Metro area. Hydrologic analysis and monitoring completed by the District in 2000/2001 indicating potential construction impacts to the springflow led to a requirement that the Minnesota Department of Transportation modify its design for a new interchange at TH 55 and TH 62. The District is continuing to monitor the spring to evaluate long-term trends.

Minnehaha Creek flow monitoring indicates that some reaches of the creek may be gaining baseflow from groundwater while other reaches may be losing baseflow, likely from a combination of natural geologic conditions and the artificial creek elevation modifications at the weirs and dams. The District is expanding its monitoring program to better understand the extent of these areas of infiltration (gain) and exfiltration (loss).

The HHPLS identified the infiltration potential of the upland areas within the subwatershed as high to medium with some areas of variability where the soils are organic in nature (see Figure 16). Most of the lower subwatershed is classified by the Hennepin County Geologic Atlas as being of high to very high aquifer sensitivity, reflecting the glacial outwash deposits that underlay the soils and the shallow depth to bedrock. The upper subwatershed, an area of loamy till, is classified as being generally of low to moderate sensitivity to pollution except along the Creek and in the large Grays Bay wetland complex (see Figure 17).

Large areas of the upper subwatershed have been designated by the Minnesota Department of Health (MDH) as Wellhead Protection Areas, including three in St. Louis Park, four in Minnetonka, and eight in Edina. The Drinking Water Sensitivity Management Areas (DWSMA) for St. Louis Park wells have been designated by the MDH to be of high risk and vulnerability to contamination of the drinking water supply while the DWSMAs for the other wellhead Protection areas are generally of low vulnerability. Figure 18 shows the DWSMAs and associated Wellhead Protection Areas.

The County Well Index has records of approximately 975 wells in the subwatershed, mostly shallow (less than 300 feet deep) domestic water supply wells but about 30 wells deeper than 500 feet, mostly municipal supply wells.

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3.0 Problems and Issues

3.1 Water Quality

1. The water quality in Minnehaha Creek as measured by total phosphorus and TSS concentrations is comparable to the MPCA’s ecoregion guidelines. Phosphorus and sediment loads in Minnehaha Creek increase upstream to downstream, although the impoundments at the major grade controls act as settling basins and trap some of the pollutants and sediment. Average chloride concentrations are generally lower than state standards, and dissolved oxygen concentrations are generally sustained at levels sufficient to maintain aquatic life. Monitoring for e. coli bacteria shows increasing concentrations from upstream to downstream at levels sometimes exceeding state standards. 2. Six lakes in the subwatershed have been designated Impaired Waters on the state’s 303(d) list due to an excess of nutrients. The District has petitioned to remove two of those lakes. The District is preparing Total Maximum Daily Load (TMDL) studies, including plans to reduce phosphorus loads into the lakes, for Nokomis, Diamond, Hiawatha, and Powderhorn Lakes. 3. The HHPLS established and the Lake Hiawatha TMDL assumes an in-creek total phosphorus concentration goal of 80 µg/L. The HHPLS estimated that achieving this goal would require a 15 percent reduction in phosphorus loading to the creek from the entire subwatershed, excluding the Chain of Lakes and Lake Nokomis lakesheds. However, not enough is known about in-stream processes and sources to partition that load reduction between loading from runoff and loading from in-stream sources such as streambank erosion, internal loading, riparian wetlands, etc. 4. Development in the subwatershed has resulted in increased stormwater volumes conveying nutrients and sediment to the lakes and to Minnehaha Creek. Significant efforts and investments by the District and the local governments have been made to improve water quality in the lakes through improvement projects, restorations, and nonstructural BMPs such as education and street sweeping. As a result Brownie Lake, Cedar Lake, Lake of the Isles, and Lake Calhoun meet or exceed their water quality goals. 5. Development, redevelopment, and reconstruction in the subwatershed may provide opportunities to obtain a net decrease in volume of stormwater runoff, nutrient and TSS loads conveyed to those water resources.

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3.2 Water Quantity

1. Drainage is conveyed through the subwatershed through a network of storm sewers, ditches, wetlands and lakes that discharge to Minnehaha Creek. The Minnehaha Creek Stream Assessment identified 35 locations on the creek with significant erosion or bank failure, and numerous locations with less severe erosion. Channel bank stability is stressed by “flashy” storm discharges which produce high velocities and rapid increases and decreases in stage coupled with poor riparian zone management and numerous storm sewer outfalls. 2. Development of the subwatershed has resulted in increased stormwater volumes and flow peaks and reduced infiltration and base flow in Minnehaha Creek. Development, redevelopment, and reconstruction in the subwatershed may provide opportunities to achieve a net decrease in volume of stormwater runoff, nutrient and TSS loads conveyed to those water resources. 3. Limitations on discharges from the Grays Bay dam, reduced infiltration and baseflow, multiple impoundments on the creek, and channel overwidening to accommodate high flows leads to extended periods when the flows and depths in the creek channel are insufficient for recreation and severely stress aquatic life. 4. Several landlocked subwatershed units and individual subbasins are present in the subwatershed, primarily in Minnetonka and St. Louis Park. As identified in the HHPLS, several of these subwatersheds or basins are being considered by the cities for outletting, altering local hydrology and potentially creating downstream volume or water quality impacts. Within these landlocked basins, any future development or redevelopment should minimize creation of new stormwater volumes. Outletting will generally be discouraged unless there is a demonstrated threat to property, structures or public safety. 5. Impoundments and grade control structures along the creek cause sediment to be deposited and accumulate, limiting habitat values. 6. The HHPLS identified multiple locations within the subwatershed that are predicted to overtop during the 100 year event, including city streets, trails, and footbridges. 7. The HHPLS identified several locations within the subwatershed where, for both existing and future conditions, high velocities may result in erosion at outlets or culverts. The Stream Assessment identified 178 storm sewer outfalls larger than eight inches in diameter discharging into the creek. Erosion control or energy dissipation measures may be required in those locations.

3.3 Wetlands

1. The subwatershed includes several wetlands with high to exceptional vegetative diversity, fish and wildlife habitat and aesthetic values – many of them riparian to Minnehaha Creek or lakes within the subwatershed - that need to be protected. 2. Most of the wetlands in the subwatershed have been impacted by development, as indicated by the lack of wetlands with exceptional to high vegetative diversity given the size of the subwatershed.

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3. Degraded wetlands with high to moderate restoration potential should be considered for protection and restoration to increase the quantity and quality of wetlands present and begin to mitigate past wetland losses from fill and degradation.

3.4 Ecological Integrity

1. Most of the subwatershed is fully developed at urban and suburban densities, with opportunities for the conservation of ecological integrity being primarily within the creek corridor or some larger wetland complexes. 2. Fish surveys have been completed by the DNR on the major lakes in the subwatershed, and the fisheries are actively managed through stocking. 3. A fish survey conducted by the DNR on Minnehaha Creek found mostly lake species with few adults, indicating a lack of suitable habitat and few refuges for overwintering and low flow periods. 4. Macroinvertebrate communities in Minnehaha Creek are limited by frequent wetland and impounded reaches, water quality, and lack of habitat. 5. Eurasian watermilfoil is present in many of the lakes, and the Minneapolis Park Board performs weed cutting on the Chain of Lakes to better support swimming and boating.

3.5 Groundwater

1. Development of the subwatershed has resulted in increased stormwater volumes and flow peaks and reduced infiltration and base flow in Minnehaha Creek. Development, redevelopment, and reconstruction in the subwatershed may provide opportunities to decrease stormwater runoff volumes and increase infiltration. 2. Ongoing flow monitoring in Minnehaha Creek suggests that some reaches of the creek are losing flow to groundwater, possibly contributing to periods of low or intermittent flow. 3. Seeps and springs are present in the subwatershed, mainly in the limestone cliffs of the Gorge. The most prominent spring is Camp Coldwater Spring. Hydrologic analysis and monitoring conducted at the time the Minnesota Department of Transportation proposed to construct a new highway interchange nearby indicate this historic spring is sensitive to impacts in its groundwatershed. 4. The extensive wetlands in the upper subwatershed were identified in the FAW as either discharge wetlands or combination recharge-discharge wetlands. It will be critical to maintain or increase infiltration rates in the upper subwatershed to help maintain hydrology to these wetlands. Wetlands in the lower subwatershed are mainly recharge or combination wetlands. The hydrology of these wetlands depends on maintaining local flow patterns and rates. 5. Much of the subwatershed is very highly or highly sensitive to aquifer impacts, including the Minnehaha Creek corridor.

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6. Wellhead Protection Areas have been identified for the cities of Edina, Minnetonka and St. Louis Park within this subwatershed. Stormwater management within those areas should be coordinated with wellhead protection plans.

3.6 Impacts of Future Growth

Land use change impacts downstream water quality by increasing the volume of runoff and the concentration and load of nutrients and sediment transported to receiving waters. The development of vacant land or conversion of developed land to other uses can be expected to affect water quality in the lakes.

Table 12 illustrates how land use change such as the expected conversion of vacant land to other uses could be expected to impact water quality in the eight lakes in the subwatershed. The table also illustrates the impact of a regulatory program managing these impacts. Powderhorn Lake was not modeled in the HHPLS so no scenarios for that lake are included here.

Ultimate development is defined as the conversion of all agricultural lands, and one-half the upland forested area identified in the 2020 land use plans of the respective local governments as remaining undeveloped after 2020. This conversion may take place by 2030 or require significantly more time; it is simply assumed that at some point in the future these conversions will occur. More detail regarding this modeling can be found in Technical Appendix A.

Table 12 contrasts three loading reduction scenarios. Scenarios 1 and 2 contrast the required load reductions if there were no regulatory program to the requirements under the existing regulatory program. The third scenario illustrates the expected result of a stringent regulatory program that strictly prohibits any new phosphorus loading.

Table 12. Modeled 2020 and ultimate development water quality and the total phosphorus loading reduction necessary to achieve in-lake total phosphorus concentration goals. Ultimate Brownie Lake Goal = 35 μg/L 2000 2020 Development Scenario 1: No Regulatory Program Predicted in-lake TP (μg/L) 40 40 P load decrease needed to achieve 35 μg/L (lbs/year) 12 Scenario 2: Current Regulatory Program Predicted in-lake TP (μg/L) 38 38 P load decrease needed to achieve 35 μg/L (lbs/year) 9 Scenario 3: Regulatory Program That Prohibits A Net Increase in Loading from New Development (As assumed in HHPLS) Predicted in-lake TP (μg/L) 38 P load decrease needed to achieve 35 μg/L (lbs/year) 7

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Ultimate Cedar Lake HHPLS Goal = 25 μg/L 2000 2020 Development Scenario 1: No Regulatory Program Predicted in-lake TP (μg/L) 23 23 P load decrease needed to achieve 25 μg/L (lbs/year) – no degradation 16 Scenario 2: Current Regulatory Program Predicted in-lake TP (μg/L) 22 22 P load decrease needed to achieve 25 μg/L (lbs/year) – no degradation 6 Scenario 3: Regulatory Program That Prohibits A Net Increase in Loading from New Development (As assumed in HHPLS) Predicted in-lake TP (μg/L) 22 P load decrease needed to achieve 25 μg/L (lbs/year) – no degradation 2

Ultimate Lake of the Isles Goal = 40 μg/L 2000 2020 Development Scenario 1: No Regulatory Program Predicted in-lake TP (μg/L) 42 42 P load decrease needed to maintain 38 μg/L (lbs/year) – no degradation 18 Scenario 2: Current Regulatory Program Predicted in-lake TP (μg/L) 38 40 P load decrease needed to maintain 38 μg/L (lbs/year) – no degradation 18 Scenario 3: Regulatory Program That Prohibits A Net Increase in Loading from New Development (As assumed in HHPLS) Predicted in-lake TP (μg/L) 39 P load decrease needed to maintain 38 μg/L (lbs/year) – no degradation 8

Ultimate Lake Calhoun Goal = 25 μg/L 2000 2020 Development Scenario 1: No Regulatory Program Predicted in-lake TP (μg/L) 23 23 P load decrease needed to maintain 21 μg/L (lbs/year) – no degradation 103 Scenario 2: Current Regulatory Program Predicted in-lake TP (μg/L) 21 22 P load decrease needed to maintain 21 μg/L (lbs/year) – no degradation 56 Scenario 3: Regulatory Program That Prohibits A Net Increase in Loading from New Development (As assumed in HHPLS) Predicted in-lake TP (μg/L) 22 P load decrease needed to maintain 21 μg/L (lbs/year) – no degradation 27

Ultimate Lake Harriet Goal = 20 μg/L 2000 2020 Development Scenario 1: No Regulatory Program Predicted in-lake TP (μg/L) 24 24 P load decrease needed to achieve 20 μg/L (lbs/year) 152 Scenario 2: Current Regulatory Program Predicted in-lake TP (μg/L) 23 23 P load decrease needed to achieve 20 μg/L (lbs/year) 132 Scenario 3: Regulatory Program That Prohibits A Net Increase in Loading from New Development (As assumed in HHPLS) Predicted in-lake TP (μg/L) 23 P load decrease needed to achieve 20 μg/L (lbs/year) 123

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Ultimate Lake Nokomis Goal = 50 μg/L 2000 2020 Development Scenario 1: No Regulatory Program Predicted in-lake TP (μg/L) 65 65 P load decrease needed to achieve 50 μg/L (lbs/year) 310 Scenario 2: Current Regulatory Program Predicted in-lake TP (μg/L) 65 P load decrease needed to achieve 50 μg/L (lbs/year) 295 Scenario 3: Regulatory Program That Prohibits A Net Increase in Loading from New Development (As assumed in HHPLS) Predicted in-lake TP (μg/L) 64 64 P load decrease needed to achieve 50 μg/L (lbs/year) 288

Ultimate Lake Hiawatha Goal = 50 μg/L TMDL = 61 μg/L 2000 2020 Development Scenario 1: No Regulatory Program Predicted in-lake TP (μg/L) 74 74 P load decrease needed to achieve 61 μg/L (lbs/year) 1,833 Scenario 2: Current Regulatory Program Predicted in-lake TP (μg/L) 72 72 P load decrease needed to achieve 61 μg/L (lbs/year) 1,580 Scenario 3: Regulatory Program That Prohibits A Net Increase in Loading from New Development (As assumed in HHPLS) Predicted in-lake TP (μg/L) 72 P load decrease needed to achieve 61 μg/L (lbs/year) 1,507

Ultimate Diamond Lake Goal = 90 μg/L; TMDL = 90 μg/L 2000 2020 Development Scenario 1: No Regulatory Program Predicted in-lake TP (μg/L) 149 149 P load decrease needed to achieve 90 μg/L (lbs/year) 180 Scenario 2: Current Regulatory Program Predicted in-lake TP (μg/L) 141 145 P load decrease needed to achieve 90 μg/L (lbs/year) 166 Scenario 3: Regulatory Program That Prohibits A Net Increase in Loading from New Development (As assumed in HHPLS) Predicted in-lake TP (μg/L) 143 P load decrease needed to achieve 90 μg/L (lbs/year) 159

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4.0 Resource Management Goals and Strategies

The following section presents the 17 watershed goals approved by the MCWD, measurable objectives, metrics and the specific goals and actions for the Minnehaha Creek subwatershed.

4.1 Abstraction/Filtration

MCWD Goal 1: Abstraction/Filtration. Promote abstraction and filtration of surface water where feasible for the purposes of improving water quality and increasing groundwater recharge throughout the watershed.

Discussion: Development and the associated creation of new impervious surface increase the volume of stormwater runoff. The new runoff volume can convey more pollutants to receiving waters and may increase erosion and sediment transport, negatively affecting water quality. Development also decreases the amount of stormwater that naturally percolates into the soil to recharge groundwater, thus reducing baseflow in streams, changing hydrology in groundwater- fed wetlands, and decreasing water availability in drinking water aquifers. The Minnehaha Creek subwatershed is almost entirely developed, and those hydrologic impacts have already occurred.

Abstraction of stormwater (retained on site through infiltration, evapotranspiration, or capture and reuse) reduces the amount of runoff from site conveying pollutants. The most common type of abstraction, infiltration, reduces runoff, which helps recharge groundwater. Filtration offers an opportunity to use soil to naturally cleanse stormwater prior to discharge. Increased aabstraction and filtration in the Minnehaha Creek subwatershed is desirable for several reasons:

• A reduction in the amount of pollutant loading into Minnehaha Creek and the lakes conveyed by runoff; • An increase in shallow groundwater recharge to help increase baseflow in the Creek; • A reduction in runoff peak flows and overall volumes that now erode streambanks; • Protection of the hydrology of the groundwater-fed wetlands in the subwatershed; and • The lake TMDLs will rely in part on increased infiltration in the lakesheds to help achieve lake water quality goals.

A key strategy to achieve this goal is the adoption of a volume management standard for new development and redevelopment that requires the abstraction of one inch of rainfall. Much of the subwatershed has at least moderate infiltration potential. Requiring new development and redevelopment to abstract some of the new stormwater generated and encouraging retrofitting to increase infiltration on existing sites would reduce runoff volumes and help reduce future

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downstream erosion in streams and channels or flooding in landlocked basins; minimize additional pollutant loading that would have been conveyed by that stormwater; and help maintain groundwater levels, preserving wetland hydrology and stream baseflows.

Because the Minnehaha Creek subwatershed is almost entirely developed, there will be few new opportunities to implement abstraction. The primary strategies will be providing for infiltration on infill development and redevelopment, and retrofitting existing development. The phosphorus load reduction plan for Lake Hiawatha incorporates an expectation of a significant reduction of pollutant loading from existing development Abstraction and infiltration are important tools in achieving that load reduction and to prevent further degradation of the other lakes, streams, and wetlands.

Desired Outcomes: Increased infiltration, reduction in pollutant loading and volumes of runoff to supplement other goals.

Metrics: Acre-feet of infiltration to meet nutrient loading reductions for water quality and volume reductions for water quantity goals.

Minnehaha Creek Goal 1.1: Increase abstraction and infiltration to reduce runoff volumes carrying pollutant loads to the lakes and streams in the subwatershed and to promote groundwater recharge.

Action A. In consultation with LGUs through an appropriate rulemaking process, amend existing or establish new District rules requiring abstraction of the first one inch of rainfall on new permitted development and redevelopment. Action B. Work cooperatively with the LGUs in the subwatershed to identify areas suitable for regional infiltration areas. Action C. Construct regional infiltration basins on a cooperative basis with LGUs where additional infiltration is desired. Action D. Promote reforestation and revegetation with native plants to increase infiltration. Action E. Develop infiltration strategies appropriate to wellhead protection areas and areas of groundwater sensitivity. Action F. Provide technical assistance to LGUs and developers to foster low impact development and redevelopment that minimizes new impervious surface and provides for increased infiltration. i. Develop and distribute model ordinances and design standards that incorporate low impact design principles. ii. Sponsor educational opportunities for LGU staff, developers, elected and appointed officials and other interested parties to provide practical information and opportunities for sharing experiences. iii. Provide education and training opportunities, technical and planning assistance for property owners and LGUs on methods

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to reduce runoff from and increase infiltration on their property by incorporating BMPs into landscaping, infrastructure maintenance, and reconstruction. iv. Encourage the use of infiltration as a Best Management Practice within landlocked basins of the subwatershed. v. Develop a small grant program to provide financial assistance to property owners desiring to retrofit their property with BMPs to increase infiltration.

4.2 Ecological Integrity

MCWD Goal 2: Ecological Integrity. Promote activities that maintain, support and enhance floral, faunal quantity and ecological integrity of upland and aquatic resources throughout the watershed.

Discussion: The Minnehaha Creek subwatershed has few large tracts of minimally developed area save for some large wetland complexes in the upper subwatershed. There is potential to create an ecological corridor through the watershed centered on Minnehaha Creek and the wetland complexes through which it flows. Such a corridor along the Creek would connect Lake Minnetonka, the Chain of Lakes, and the Mississippi River.

Connected corridors are desirable as they provide a variety of habitats both aquatic and terrestrial as well as protected areas for passage. Within these conservation areas wherever possible the District would promote the conservation or establishment of native vegetation to increase or maintain infiltration rates; decrease or maintain runoff rates and pollutant conveyance to water resources; and minimize erosion of shorelines and streambanks. Sustaining or improving water quality and ecological integrity is necessary to meet the District goals in this plan as well as to meet state and federal nondegradation, water quality and biological integrity requirements and to comply with existing and prevent the need for future TMDLs.

The ecological community in Minnehaha Creek is impaired by its hydrology and lack of habitat as well as the existing water quality. A wide corridor that includes stream buffers maintained with native vegetation, vegetated streambanks, and in-stream habitat for fish and macroinvertebrates is desirable to help improve the ecological integrity of Minnehaha Creek and the area through which it flows. Strategies to achieve this long-term goal include conservation of land on which to create or conserve buffers; establishment or conservation of native vegetation; restoration of streambanks and creation of new in-stream habitat; and close management of streamflows in Minnehaha Creek to minimize extreme variations in streamflow and maintain baseflow sufficient to sustain aquatic life.

The primary strategies for improving aquatic communities within the lakes are the development and implementation of aquatic vegetation management plans, and improvement of water quality. There are a few wetlands in the subwatershed with exceptional or high vegetative diversity. These would be inspected at least annually for invasive vegetative species.

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Desired Outcomes: Functional and healthy ecological corridors and waters throughout the subwatershed.

Metrics: • Macroinvertebrate Index of Biotic Integrity (M-IBI) in Minnehaha Creek • Stream Visual Assessment Protocol (SVAP) in Minnehaha Creek • Acres of land conserved in Key Conservation Areas • Linear feet and width of riparian areas protected in Key Conservation Areas • Acres of restored/created wetland within Key Conservation Areas

Minnehaha Creek Goal 2.1: Maintain and improve overall ecological integrity within the subwatershed.

Action A. Continue Land Conservation Program efforts to proactively seek out conservation opportunities in areas identified in this plan as District priority areas. Action B. Protect existing fish and wildlife habitat and promote the development of additional habitat areas and corridors by the conservation and restoration of key ecological areas (see Figure 19). i. Require LGUs to recognize District key conservation areas in their natural resources and land use planning and to identify in their Local Water Management plans how they intend to conserve their ecological values. ii. Provide education and training opportunities, technical and planning assistance, and financial incentives to LGUs to actively conserve key ecological areas. iii. Restore areas of degradation within key conservation areas.

Action C. Work cooperatively with the LGUs, Minneapolis Park Board, DNR, National Park Service, other agencies and organizations to improve upon existing conservation corridors and where practical, develop new conservation corridors along Minnehaha Creek. Action D. Identify keystone, umbrella, and indicator species to serve as indicators of ecological integrity, evaluate existing habitat within the subwatershed, and develop strategies for the conservation of that habitat. Action E. Provide regulatory incentives for the conservation of undisturbed or creation of new native vegetation as sites develop.

Minnehaha Creek Goal 2.2: Maintain conditions suitable for healthy and varied sport fish communities within the primary lakes of the subwatershed.

Action A. Work cooperatively with the DNR and the Minneapolis Park Board in fishery management efforts.

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Action B. Achieve lake water quality and clarity goals to maintain or improve habitat conditions. Action C. Manage aquatic vegetation in accordance with a vegetation management plan that takes into account fishery habitat requirements.

Minnehaha Creek Goal 2.3: Maintain a healthy aquatic vegetation community.

Action A. Develop and implement a plan to monitor wetlands with exceptional or high vegetative diversity for presence of exotic vegetative species. Action B. Assist the MPRB in evaluating and implementing an Aquatic Plant Management Plan for the Minneapolis Chain of Lakes.

Minnehaha Creek Goal 2.4: Improve Minnehaha Creek riparian vegetation management.

Action A. Promote native vegetation over structural streambank stabilization where practical and effective in District policies, regulations, and programs. Action B. Where compatible with other uses, promote restoration of riparian zone vegetation.

Minnehaha Creek Goal 2.5: Maintain conditions suitable for a healthy and varied biologic community in Minnehaha Creek.

Action A. Complete a TMDL identifying stressors causing impaired biotic conditions in Minnehaha Creek, and develop and implement strategies for improvement. Action B. Reduce phosphorus and sediment in Minnehaha Creek and minimize periods of low dissolved oxygen. i. Prepare a Minnehaha Creek Diagnostic Study to identify sources of phosphorus and sediment in the creek, and develop and implement strategies for improvement, potentially incorporating specific watershed phosphorus load reductions assigned to LGUs in the subwatershed. ii. In collaboration with riparian cities, agencies, and infrastructure owners repair identified erosion locations in Minnehaha Creek and develop strategies to prevent future erosion and sediment transport. iii. Implement the water quantity improvement actions of this plan to limit periods of erosive velocities in the creek and maintain/stabilize base flows in the creek. Action C. In collaboration with riparian cities and property owners, other agencies, and infrastructure owners, construct priority stream restorations to improve in-stream fish and invertebrate habitat and near-stream conditions. The highest priority for restoration are those non-impounded reaches where the M-IBI score is below the Minnesota impairment threshold for streams of the Creek’s region, size, and type,

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or where the Stream Visual Assessment Protocol (SVAP) mean score is less than 5.0. Construct improvements in other reaches as opportunities arise. Action D. Monitor the fish and macroinvertebrate communities every 2-3 years. Action E. Use the results of the Minnehaha Creek Biotic Integrity TMDL and Minnehaha Creek Diagnostic Study to refine the identification and prioritization of potential in-stream, streambank and riparian zone improvements to increase macroinvertebrate and fish habitat and streambank and buffer conditions and incorporate those findings into the Capital Improvement Program. Action F. Periodically update the Minnehaha Creek stream assessment to assess current stream condition and ecological integrity. Action G. Woody debris that falls in Minnehaha Creek or other streams shall only be removed if it causes an obstruction to navigation or flow such that streambanks are destabilized or eroded or the Creek is caused to overtop its banks. Such debris shall be removed by the District or by cooperative arrangement with the LGU at the owner’s expense.

4.3 Water Quality

MCWD Goal 3. Water Quality. Preserve, maintain and improve aesthetic, physical, chemical and biological composition of surface waters and groundwater within the District.

Discussion: The HHPLS used an extensive public input process to establish water quality goals for the primary receiving waters in the District, focusing primarily on identifying target total phosphorus concentrations. In addition, Total Maximum Daily Load studies for four lakes in this subwatershed will establish phosphorus load reduction goals and strategies to reduce excess nutrient concentrations. This plan identifies those phosphorus goals plus additional goals related to water quality and sets forth a set of actions the District will undertake to reduce pollutant loading in the subwatershed and achieve water quality goals. The achievement of these water quality goals is not only necessary to meet state and federal water quality requirements and to prevent future TMDLs, but also to meet this plan’s ecological integrity goals.

Desired Outcomes: Achievement of in-lake nutrient concentration goals through achievement of nutrient loading reductions.

Metrics: • In-lake nutrient concentrations/Trophic State Index Scores (TSI) for the lakes within the subwatershed • Nutrient loading goals (lbs) for the lakes within the subwatershed

Minnehaha Creek Goal 3.1: Achieve in-lake total phosphorus concentration goals as identified in lake TMDLs and this plan.

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Action A. Partner with the Minneapolis Park Board and City of Minneapolis to investigate and implement potential internal load reductions identified in the Lake Nokomis, Powderhorn Lake, and Diamond Lake TMDLs. Action B. Amend existing or establish new District rules requiring greater than 50 percent phosphorus removal on new permitted development and redevelopment within the Minnehaha Creek subwatershed. Action C. Provide assistance to LGUs and developers to foster low impact development and redevelopment that minimizes new phosphorus and sediment loading. i. Develop and distribute model ordinances and design standards that incorporate low impact design principles. ii. Sponsor educational opportunities for LGU staff, developers, elected and appointed officials and other interested parties to provide practical information and opportunities for sharing experiences. Action D. Promote the general application of BMPs across the subwatershed. i. Consider developing a small grant program to provide financial assistance to property owners desiring to retrofit their property with BMPs to reduce phosphorus and sediment loading. Action E. Continue partnering with the Minneapolis Park Board on regular water quality monitoring in the lakes to assess progress toward achieving the in-lake phosphorus goals. Action F. Require LGUs to maintain or reduce phosphorus loading from developed uses as set forth in Section 5.6.1 of this plan within 10 years. i. Provide education and training opportunities, technical and planning assistance for property owners and LGUs on methods to reduce phosphorus and sediment loading by incorporating BMPs into landscaping, infrastructure maintenance, and reconstruction.

Minnehaha Creek Goal 3.2: Achieve and maintain other state lake water quality standards including >1.4 m Secchi clarity and 14 ug/L chl-a for deep lakes, and >1.0 m Secchi clarity and 20 ug/L chl-a for shallow lakes.

Action A. Undertake the actions specified in this Plan to achieve and maintain in- lake total phosphorus goals. Action B. Manage aquatic vegetation in accordance with a vegetation management plan that takes into account water clarity goals. Action C. Develop a water quality index which encompasses the District’s broader definition of water quality.

Minnehaha Creek Goal 3.3: Achieve and maintain an annual total phosphorus concentration in Minnehaha Creek of 80 ug/L, and maintain other parameters at ecoregion averages or better.

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Action A. Prepare a Minnehaha Creek Diagnostic Study to identify sources of phosphorus and sediment in the creek, and develop and implement strategies for improvement. Action B. Require LGUs to maintain or reduce phosphorus loading from developed uses as set forth in Section 5.6.1 of this plan within 10 years. i. Provide education and training opportunities, technical and planning assistance for property owners and LGUs on methods to reduce phosphorus and sediment loading by incorporating BMPs into landscaping, infrastructure maintenance, and reconstruction. Action C. Based on the results of the Diagnostic Study, Biotic Integrity TMDL, and Stream Assessment, identify and construct projects to reduce existing non-point source pollution loading to the creek, focusing on areas close to the creek with little stormwater detention. See Figure 20 for areas identified in the Stream Assessment as high priority for improvement. Action D. Inspect known erosion-prone areas of Minnehaha Creek at least annually to identify any new areas of erosion, and the entire creek at least every five years. Action E. In collaboration with riparian cities, agencies, and infrastructure owners improve degraded stream reaches for the purposes of bank stabilization, reducing sediment loads, preserving existing stream courses, improving habitat, and ecological enhancement. See Figure 20 for areas identified in the Stream Assessment as high priority for improvement. Action F. In collaboration with riparian cities, agencies, and infrastructure owners spot repair identified erosion locations in Minnehaha Creek and develop strategies to prevent future erosion and sediment transport. Action G. Continue to investigate possible causes of periodic e.coli exceedances in Minnehaha Creek and develop strategies to address them. Action H. Continue to monitor water quality in Minnehaha Creek.

4.4 Public Health

MCWD Goal 4. Public Health. Minimize the risks of threats to public health through the development of programs, plans and policies that improve the quality of surface and groundwater resources.

Discussion: Threats to public health in the Minnehaha Creek subwatershed relate to pathogens found in the waters. Sewage overflows from sanitary sewer breaks or improperly functioning infrastructure could result in overflows discharged to downstream water resources. An additional potential source of pathogens is waterfowl, which are attracted to open water with easy routes from the water to vegetation on shore. The Minneapolis Park Board monitors

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beaches on the lakes in Minneapolis and manages necessary closures when bacteria counts exceed state health standards. Ongoing monitoring in Minnehaha Creek has found periodic e. coli exceedances in the Creek. The District’s role in minimizing risks to public health will be to continue monitoring the Creek to diagnose potential sources for those exceedances and to develop a plan for addressing them.

Desired Outcomes: Minimization of threats to public health from contact with contaminated surface waters.

Metrics: Reported cases of illness transmission via surface water contact.

Minnehaha Creek Goal 4.1: Minimize risks to human health and water quality from land use activities.

Action A. Work cooperatively with the state, Hennepin County and LGUs to provide BMP information and technical assistance to individual sewage treatment system owners.

Minnehaha Creek Goal 4.2: Maintain a vegetated shoreline on lakes, streams and wetlands where practical and effective to reduce overpopulation with waterfowl.

Action A. Promote native vegetation over structural streambank stabilization where appropriate in District policies, regulations, and programs. Action B. Work cooperatively with LGUs and property owners to restore native streambank and lakeshore vegetation where appropriate. i. Provide education and training opportunities, technical and planning assistance, and demonstration project funding to LGUs to assist them in restoring lakeshores, streambanks and buffers on public property such as parks and open spaces, taking into consideration the balance between recreational use and ecosystem needs. ii. Develop and distribute written material to shoreline property owners explaining the benefits of lakeshore and streambank restoration and buffer creation to waterfowl control and providing design, plant selection, installation, and maintenance advice.

Minnehaha Creek Goal 4.3: Require LGUs and other agencies to manage public sanitary sewer infrastructure to minimize sewage overflows and to minimize impacts from those overflows on District water resources.

4.5 Water Quantity

MCWD Goal 5. Water Quantity. Maintain or reduce existing flows from drainage within the watershed to decrease the negative effects of stormwater runoff and bounce from existing and proposed development as well as provide low flow augmentation to surface waters.

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Discussion: Development and the associated creation of new impervious surface increases the volume of stormwater runoff from the landscape, changes the rates and times to peak runoff flow, and decreases the amount of stormwater that naturally percolates into the soil to recharge groundwater. The District’s long term goal in the Minnehaha Creek subwatershed is to achieve no increase in the volume of stormwater discharged from the subwatershed into Minnehaha Creek and thence into the Mississippi River. Implementation strategies will include minimizing new runoff volumes from development and redevelopment, encouraging infiltration and groundwater recharge to maintain baseflow in the Creek and adequate hydrology to groundwater-fed wetlands, and limiting new volumes from existing landlocked subwatersheds.

A key strategy to achieve this goal is the adoption of a volume management standard for new development and redevelopment that requires the abstraction (removal from runoff through infiltration, capture and reuse, evapotranspiration, etc.) of one inch of rainfall. Approximately 70 percent of annual runoff volume in Minnesota results from precipitation events of 1” or less (MPCA, 2000). Requiring new development and redevelopment to abstract (retain on site through infiltration, evapotranspiration, or capture and reuse) runoff from that size event would significantly reduce new volumes of runoff flowing downstream and help reduce future erosion in streams and channels; minimize new pollutant loading that would have been conveyed by that stormwater; and help maintain groundwater levels, preserving wetlands.

Limiting discharges from subwatersheds and basins that are currently landlocked is necessary to prevent further degradation of downstream water quality as well as to limit new volumes discharged downstream to channels that are already experiencing erosion.

In the Minnehaha Creek subwatershed, another challenge will be balancing regulated flows from the Grays Bay dam to manage levels in Lake Minnetonka with providing for adequate flow in the Creek to maintain aquatic life and recreational use while limiting volumes conveyed to the Creek in erosion-prone areas.

The phosphorus load reduction plan for Lake Hiawatha incorporates an expectation of a significant reduction of pollutant loading from existing development through abstraction and infiltration. The additional new volume and the existing volume for improving downstream water quality could be mitigated through construction of regional infiltration basins, restoring drained wetlands, reforestation and revegetation, or other means.

Table 13. Modeled annual volume of runoff in the Minnehaha Creek subwatershed, and estimated reductions resulting from application of a proposed 1” abstraction rule for new development and redevelopment (acre- feet). 2000 modeled annual subwatershed runoff volume 10,240 2020 modeled annual subwatershed runoff volume 10,470 Ultimate Development modeled annual subwatershed runoff volume 10,470 Increase between 2000 and Ultimate Development 230 Estimated volume abstracted by 1” rule 161 New volume to be abstracted through other means such as capital projects, wetland 69 restorations, reforestation and revegetation, etc. Total volume reduction needed to reduce pollutant loading to Minnehaha Creek as 1,298 set forth in the Lake Hiawatha TMDL

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Desired Outcomes: Management of water volumes discharged from the subwatershed.

Metrics: Acre-feet volume abstraction.

Minnehaha Creek Goal 5.1: Manage water volume to Minnehaha Creek in a way that balances desirable Lake Minnetonka and Minnehaha Creek levels and flows with recreation and ecological needs and channel impacts.

Action A. Manage Lake Minnetonka discharges according to the Headwaters Control Structure Management Policy and Operating Procedures. Action B. Continue to partner with the US Army Corps of Engineers and the DNR to explore options for adjusting the Grays Bay dam operating plan to balance maintenance of desirable Lake Minnetonka and Minnehaha Creek levels with recreation and ecological needs and impacts. Action C. Identify baseflow in Minnehaha Creek and continue to investigate the role of groundwater in gain or loss of baseflow. Action D. Continue to monitor flows in Minnehaha Creek.

Minnehaha Creek Goal 5.2: Reduce volume of stormwater runoff from new development and redevelopment and maintain existing water volume discharged from the subwatershed into Minnehaha Creek.

Action A. Consider amending existing or establishing new District rules requiring abstraction of the first one inch of rainfall on new permitted development and redevelopment. Action B. Track volumes abstracted and new volumes created resulting from permitted development. Action C. Work cooperatively with the LGUs in the subwatershed to identify and construct abstraction and infiltration opportunities to reduce pollutant loading to Minnehaha Creek and thus Lake Hiawatha. Action D. Provide assistance to LGUs and developers to foster low impact development and redevelopment that minimizes new stormwater volumes. i. Develop and distribute model ordinances and design standards that incorporate low impact design principles. ii. Sponsor educational opportunities for LGU staff, developers, elected and appointed officials and other interested parties to provide practical information and opportunities for sharing experiences. iii. Provide education and training opportunities, technical and planning assistance for property owners and LGUs on methods to reduce runoff from and increase infiltration on their property by incorporating BMPs into landscaping, infrastructure maintenance, and reconstruction.

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Action E. Encourage the development and maintenance of depressional storage within the subwatershed.

Minnehaha Creek Goal 5.3: Limit new discharges from land locked basins and subbasins to prevent new impacts to downstream lakes.

Action A. Require the LGUs to continue to manage basins without outlets as landlocked basins unless they can demonstrate that providing outlets would not negatively impact downstream water resources (see Figure 2 for landlocked basin locations).

Minnehaha Creek Goal 5.4: Require public stormwater conveyance and control structures in the watershed be sized and maintained properly to convey current and ultimate stormwater flows to minimize flooding and erosion potential.

Action A. Require LGUs to provide to the District a copy of their annual NPDES report.

4.6 Shorelines and Streambanks

MCWD Goal 6. Shorelines and Streambanks. Preserve the natural appearance of shoreline areas and minimize degradation of surface water quality which can result from dredging operations.

Discussion: Eroding shorelines and streambanks contribute to the degradation of water quality. Native vegetation can effectively stabilize these areas, filter runoff for sediment and other pollutants, and provide habitat.

The key areas identified in this plan for conservation activities include buffer zones adjacent to Minnehaha Creek. In some cases these buffer zones are riparian or flow-through wetlands, and those wetlands have been identified as key conservation areas. Where streams and channels flow through upland areas, conservation of native vegetation within these zones would also increase or maintain infiltration rates; decrease or maintain runoff rates and pollutant conveyance to water resources; and help minimize erosion. Restoration of lakeshore would have the same benefits. Sustaining or improving water quality and ecological integrity is necessary to meet District goals as well as to meet state and federal nondegradation, water quality and biological integrity requirements and to prevent the need for future TMDLs.

The District recognizes that many areas along the creek have historically been held within the public domain for public use. Public use can be defined in a number of ways including stormwater conveyance, recreational features and amenities as well as ecosystem functions. The Minnehaha Creek Visioning Partnership was convened to provide recommendations on achieving balance between these various, sometimes competing, functions. Due to the desire to have multifunctional landscapes throughout the Creek corridor, the District is committed to

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working with collaborative partners to achieve mutual goals. Stable streambanks and shorelines adjacent to public resources are assumed to be in the interest of all parties who own and manage public resources throughout the subwatershed.

Restoration of streambanks on Minnehaha Creek is a key strategy for meeting this plan’s goals. The Minnehaha Creek Stream Assessment identified locations where restoration and the creation of buffer zones may be desirable and feasible. This restoration would be accomplished through cooperative projects to restore high-priority stream reaches and to perform spot repairs of eroded locations.

Desired Outcomes: Stable streambanks and shorelines to supplement other goals.

Metrics: • Stream Visual Assessment Protocol (SVAP) in Minnehaha Creek • Linear feet of stabilized eroded shoreline and streambank • Linear feet of shoreline protected in Key Conservation areas • Linear feet and width of riparian areas protected in Key Conservation Areas

Minnehaha Creek Goal 6.1: Where appropriate, collaboratively work to stabilize and/or restore degraded streambanks and riparian zones on Minnehaha Creek to help meet pollutant loading reduction and ecological integrity goals.

Action A. In collaboration with riparian cities and property owners, agencies, and infrastructure owners construct priority streambank and buffer improvements to stabilize streambanks and riparian zones and to repair existing erosion and reduce the risk of future erosion. The highest priority for stabilization are those non-impounded reaches identified in the Minnehaha Creek Stream Assessment where the Pfankuch stability rating relative to Rosgen stream type is “Fair” or “”Poor” or where the Stream Visual Assessment Protocol (SVAP) mean score is less than 5.0. Construct improvements in other reaches as opportunities arise. Figure 20 illustrates areas of high priority for improvement based on the Stream Assessment. Action B. Use the results of the Minnehaha Creek Biotic Integrity TMDL/Diagnostic Study to refine the identification and prioritization of potential streambank and riparian zone improvements to improve streambank stability, reduce pollutant loading, and increase habitat and incorporate those findings into the Capital Improvement Program. Action C. In collaboration with riparian cities, agencies, property owners and infrastructure owners spot repair identified erosion locations in Minnehaha Creek and develop strategies to prevent future erosion and sediment transport. Action D. Promote native vegetation over structural stabilization where practical and effective in District policies, regulations, and programs.

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i. Provide education and training opportunities, technical and planning assistance, and demonstration project funding to LGUs to assist them in restoring streambanks and buffers on public property such as parks and open spaces. ii. Develop and distribute written material to riparian property owners explaining the benefits of streambank restoration and buffer creation to the reduction of pollutant loads and creation of shoreline habitat and providing design, plant selection, installation, and maintenance advice. iii. Develop a small grant program to provide financial assistance to property owners desiring to restore their shoreline or plant a buffer. Action E. Work cooperatively with the National Park Service and Minneapolis Park Board to identify necessary streambank restoration and structure improvements in Minnehaha Park from Minnehaha Falls to the Mississippi River and incorporate those findings into the Capital Improvement Program. 4.7 Navigation

MCWD Goal 7. Navigation. Maintain the hydraulic capacity of and minimize obstruction to navigation without compromising wildlife habitat in watercourses and preserve water quality and navigation appearance in shoreland areas.

Discussion: Minnehaha Creek is a canoe route enjoyed by many users. The District maintains 15 canoe landings on the creek. Several grade control structures require portages. During dry periods flow in the creek is insufficient to assure canoe passage. This plan proposes no changes to the existing grade control structures. Consultation with the Corps of Engineers will continue to determine if the Grays Bay dam operation plan can be adjusted to better balance lake and creek levels with recreation and ecological impacts.

The District will not participate in the removal of nuisance aquatic vegetation solely for the purpose of improving navigation, but may consider macrophyte control where excessive growth contributes to poor water quality

Desired Outcomes: Maximize canoe-able days while minimizing undesirable upstream and ecological impacts, minimize periods of navigational obstruction, minimize impacts on water resources from dredging.

Metrics: Number of canoe-able days, number of obstructions mitigated, compliance with dredging policy.

Minnehaha Creek Goal 7.1: Minimize new obstructions to navigation within the channel.

Action A. Maintain an open creek channel for safe canoeing by removal of navigational obstructions such as fallen trees completely blocking

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passage. Permanent obstructions should be limited to areas that can be portaged. Fallen trees shall be removed by the District or by cooperative arrangement with the LGU at the owner’s expense.

Minnehaha Creek Goal 7.2: Manage Lake Minnetonka discharge to Minnehaha Creek in a way that balances desirable Lake Minnetonka and Minnehaha Creek levels and flows with recreation and ecological needs and impacts.

Action A. Manage Lake Minnetonka discharges according to the Headwaters Control Structure Management Policy and Operating Procedures. Action B. Continue to partner with the US Army Corps of Engineers and the DNR to explore options for adjusting the Grays Bay dam operating plan to balance maintenance of desirable Lake Minnetonka and Minnehaha Creek levels with recreation and ecological needs and impacts.

Minnehaha Creek Goal 7.3: Manage dredging activities so as to preserve the natural appearance of shoreline areas; recreational, wildlife and fisheries resources of surface waters; surface water quality and ecological integrity of the riparian environment.

Action A. Regulate dredging activities in a manner consistent with local policy and Minnesota Rules Chapter 6115.0200

4.8 Best Management Practices

MCWD Goal 8. Best Management Practices. Improve water quality by promoting best management practices (BMP's), requiring their adoption in local plans and their implementation on development sites.

Discussion: This plan and District regulations stipulate the use of Best Management Practices (BMPs) to reduce stormwater volumes and pollutant loadings, but do not prescribe which practices should be used. This allows the LGU and developers the flexibility to implement those that are most appropriate for local conditions and opportunities. A key strategy for plan implementation is providing early consultation with and technical assistance to and education of stakeholders including city staff, residents, and developers to increase knowledge and acceptance of various BMPs and to promote their adoption. Generalized implementation of BMPs across the subwatershed is a strategy identified in the lake TMDLs to reduce pollutant loadings from the landscape to help achieve lake water quality standards.

Desired Outcomes: Implementation of Best Management Practices on private and public property to supplement other goals.

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Metrics: Compliance with the early consultation requirement.

Minnehaha Creek Goal 8.1: Promote best management practices as methods to help meet pollutant loading and volume reduction goals established in this subwatershed plan.

Action B. Require LGUs to identify in their local water management plans how they plan to meet specific phosphorus loading minimum reduction goals and minimize stormwater volumes from developed uses through the implementation of BMPs in the subwatershed. i. Provide education and training opportunities, technical and

MCWD Goal 9. Education and Communications. Enhance public participation and knowledge regarding District activities and provide informational and educational material to municipalities, community groups, businesses, schools, developers, contractors and individuals.

planning assistance for LGUs on methods to reduce phosphorus and sediment loading by incorporating BMPs into landscaping, infrastructure maintenance, and reconstruction. ii. Provide guidance and assistance as requested to cooperatively develop design standards and model ordinances to meet BMP requirements. Action B. To promote BMPs and encourage early consultation by developers, amend District rules to incorporate a requirement for stormwater management plan approval prior to submittal of a preliminary plat. Action C. Develop and distribute model ordinances and design standards that illustrate the proper application of various BMPs

4.9 Education and Communications

Discussion: The District conducts an active and strategic education and communication program watershed-wide to provide general information and to various stakeholder groups in accordance with its five-year strategic education and outreach plan. Targeted information will be necessary in the Minnehaha Creek subwatershed to educate these stakeholders as to the District’s goals for this subwatershed, the actions the District plans to take, and their role in conserving water resources in the subwatershed. The specific targeted messages will emphasize ways in which developers, LGUs, and individual property owners can reduce runoff from their properties.

Desired Outcomes: Stewardship over water resources by residents of the subwatershed to assist District activities and supplement other goals.

Metrics: Telephone survey.

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Minnehaha Creek Goal 9.1: Provide focused education and outreach opportunities within this subwatershed to supplement the general education and outreach program and assist in the achievement of these subwatershed goals.

Action A. Develop and distribute targeted written material to stakeholder groups (e.g., residents, LGUs, developers) explaining the need for phosphorus and other pollutant loading reduction and increased infiltration and providing strategies that each stakeholder group can employ to assist in meeting this goal. Action B. Sponsor educational opportunities for LGU staff, developers, elected and appointed officials and other interested parties to provide practical information and opportunities for sharing experiences. Action C. Prepare and distribute timely news releases to coincide with education efforts to inform the public of BMPs and other District actions that affect them directly.

Minnehaha Creek Goal 9.2: Work cooperatively with other agencies and groups to coordinate education and outreach efforts to avoid duplication of efforts and maximize resources.

4.10 Ditches

MCWD Goal 10. Public Ditches. Maintain public ditch systems within the District as required under Statutory jurisdiction.

Discussion: None of the three public ditches within this subwatershed perform the function for which they were originally established – to drain lands for the promotion of agriculture. The ditches for the most part have been converted to storm sewer. Because those ditches are of localized rather than watershed-wide benefit, the Board will pursue turning jurisdiction of these ditches over to the local community.

Desired Outcomes: Manage public ditches to maintain drainage.

Metrics: Inspection requirements.

Minnehaha Creek Goal 10.1: Turn over to local communities jurisdiction over public ditches that no longer perform their original function and that serve mainly as local stormwater conveyances.

Action A. If the cities are willing, turn back County Ditch #14, #17, and #29 to the cities served by them. Action B. Until such time as the proposed jurisdictional turnbacks are completed, manage the ditches in accordance with statutory rights and responsibilities, conducting annual inspections and making improvements as required.

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4.11 Wetlands

MCWD Goal 11. Wetlands. Preserve, create and restore wetland resources and maximize the benefits and functionality of wetlands to the watershed.

Discussion: The Functional Assessment of Wetlands evaluated 2,661 acres of wetlands in the Minnehaha Creek subwatershed, of which 1,035 acres were in the Preserve classification (see Table 9 in Section 2.5.4 and Figure 12). Most of the wetlands in the Preserve category are riparian or flow-through to the creek. Their conservation is integral to achieving ecological integrity goals, as well as water quality, stormwater management, and floodplain management goals.

A key strategy of this plan is regulation of wetland impacts in accordance with a management classification based on the functions and values findings of the Functional Assessment of Wetlands (FAW). Wetlands are assigned to a classification – either Preserve or Manage 1, 2, or 3 – and allowable impacts would be based on that classification. The wetlands with the highest values – those in the Preserve classification – would be allowed minimal impacts. The Manage classifications would be allowed some impacts, such as accepting new stormwater discharges, depending on classification. This strategy will conserve existing high values such as habitat, vegetative diversity, and sensitivity, while also recognizing that wetlands play an important part in managing stormwater. Wetlands provide essential storm and flood water storage.

Wetlands of exceptional or high vegetative diversity or fish or wildlife habitat value have been designated key conservation areas, as have wetlands that are riparian to streams or channels, have high restoration potential, provide key floodplain storage, or are located in important natural resources conservation areas such as wildlife corridors.

Except for those in the Preserve classification, which will be managed to an even higher standard, these conservation wetlands will be managed as if they were Manage 1 classification wetlands, with limitations on the amount of new runoff that can be directed to them, and a requirement to pretreat any new discharges to them.

An important part of achieving the goal of no net loss of wetland size, quality, and type will be tracking those impacts to assist in identifying future restoration or wetland creation needs.

Equally important to the regulation of wetlands is the restoration of degraded wetlands within the subwatershed. Figure 14 identifies wetlands based on restoration potential as evaluated in the FAW. Restoring wetlands increases specific functions and values of the resource within the watershed ranging from management of flows to water quality improvement to enhancement of the overall ecosystem, particularly within identified corridors. There are a limited number of small wetlands in the subwatershed with moderate to low restoration potential.

Desired Outcomes: Maintain existing quantity and quality of wetlands throughout subwatershed; improve wetland and surface water quality within Key Conservation Areas.

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Metrics: • Wetland quantity (acres) • Wetland quality (acres/management classification) • Acres of restored/created wetland within Key Conservation Areas

Minnehaha Creek Goal 11.1: Maintain existing acreage of wetlands in the subwatershed and achieve no net loss in their size, quality, type, and biological diversity.

Action A. Regulate wetland impacts commensurate with the quality of the wetland as determined by the Management Classifications identified in the Functional Assessment of Wetlands (FAW). Action B. In consultation with LGUs through an appropriate rulemaking process, amend existing or establish new District rules requiring submittal of a functions and values assessment for all proposed wetland impacts requiring a permit; mitigation of all fill in Preserve category wetlands; and specifying by management classification stormwater discharge pretreatment, buffer, hydroperiod, and other wetland standards. Action C. Require that wetland losses be mitigated within the Minnehaha Creek subwatershed. Action D. Track wetland losses resulting from permitted fill. Action E. Restore degraded wetlands in Key Conservation Areas to improve vegetative diversity and ecological integrity, with priority given to wetlands where restoration could improve management classification to at least a Manage 1. Restore other wetlands as opportunities arise. Action F. Restore vegetative diversity and ecological integrity of all wetlands in which the District acquires an interest. Action G. Update the MCWD Functional Assessment of Wetlands to maintain a current inventory of wetland location, size as well as function and value.

Minnehaha Creek Goal 11.2: Increase the quantity, quality, and biological diversity of Minnehaha Creek subwatershed wetlands through the restoration of impacted wetlands or creation of new wetlands.

Action A. Work cooperatively with the LGUs to identify potential locations within the subwatershed for future wetland creation.

4.12 Groundwater

Watershed Goal 12. Groundwater. Protect and maintain existing groundwater flow, promote groundwater recharge and improve groundwater quality and aquifer protection.

Discussion: Maintenance of groundwater recharge is important in the Minnehaha Creek subwatershed to maintain baseflow in the Creek and hydrology to the groundwater-fed discharge or combination wetlands as well as to recharge aquifers that supply public and private water

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wells. Springs and seeps in the Mississippi Gorge are also important groundwater resources in this subwatershed. Development, with the associated creation of new impervious surface, increases the volume of stormwater runoff and reduces the amount of stormwater that naturally percolates into the soil to recharge groundwater.

Increased infiltration is desirable for two primary reasons: to reduce the amount of pollutant loading into Minnehaha Creek, the lakes and wetlands, and to protect the hydrology of high- value groundwater resources such as the springs and seeps and wetlands. Much of the subwatershed has at least moderate infiltration potential. Requiring new development and redevelopment to infiltrate some of the new stormwater generated would reduce new volumes downstream and help reduce future erosion in streams and channels; minimize new pollutant loading that would have been conveyed by that stormwater; and help maintain groundwater levels, preserving wetlands.

Some parts of the subwatershed are areas of aquifer sensitivity or are drinking water wellhead protection areas, where care should be taken when infiltrating stormwater. Proper design of infiltration practices is necessary to avoid groundwater contamination. Other land use practices such as the use of private water wells or individual sewage treatment systems should be monitored to prevent contamination of groundwater resources.

Groundwater management in the Minnehaha Creek subwatershed will focus on increasing the amount of infiltration in the subwatershed and monitoring flow at high-value groundwater resources such as Camp Coldwater Spring.

Desired Outcomes: Maintain function of existing groundwater flow, assist in the protection of drinking water supply, no degradation in surficial groundwater quantity or quality, protection of high-value groundwater resources.

Metrics: • Acre-feet volume abstraction • Surficial groundwater levels and parameters

Minnehaha Creek Goal 12.1: Protect and maintain groundwater recharge and groundwater quality.

Action A. Amending existing or establish new District rules requiring abstraction of the first one inch of rainfall on new permitted development and redevelopment. Action B. Establish new District rule requiring an additional level of analysis and review of permitted development and redevelopment where there is a potential to adversely impact groundwater connected to a surface water feature. Action C. Require pretreatment of stormwater discharged to wetlands or infiltration areas in the in the areas of high aquifer sensitivity.

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Action D. Coordinate stormwater and groundwater management within identified drinking water management areas and wellhead protection areas with city and private wellhead protection plans. Action E. Develop infiltration strategies appropriate to wellhead protection areas and areas of groundwater sensitivity. Action F. Work cooperatively with Hennepin County, the Minnesota Department of Health, and other agencies charged with managing individual sewage treatment systems and private and public groundwater wells to assess the potential impacts of surface water management practices on groundwater quality. Action G. Provide assistance to LGUs and developers to foster low impact development and redevelopment that minimizes new impervious surface and provides for increased infiltration. i. Develop and distribute model ordinances and design standards that incorporate low impact design principles. ii. Sponsor educational opportunities for LGU staff, developers, elected and appointed officials and other interested parties to provide practical information and opportunities for sharing experiences. Action H. Identify a network of surficial aquifer monitoring wells across the entire Minnehaha Creek watershed, monitor groundwater levels and groundwater quality, and if change is detected identify strategies for addressing that change.

Minnehaha Creek Goal 12.2: Protect and maintain groundwater flow.

Action A. Identify base level flow in Minnehaha Creek, monitor for trends, and if change is suspected identify strategies for addressing that change. Action B. Continue to monitor groundwater flow at Camp Coldwater Spring and monitor activities within its groundwatershed for potential impacts to the historic spring.

4.13 Floodplains

Watershed Goal 13. Floodplains. Reduce the severity and frequency of flooding and high water by preserving and increasing the existing water storage capacity below 100-year flood elevations on all waterbodies within MCWD.

Discussion: The primary strategy in the management of stormwater and prevention of flooding in the Minnehaha Creek subwatershed is the preservation of the stormwater storage. Key areas identified in this plan for conservation include wetlands that provide floodplain storage and areas that provide channel and stream floodplain and riparian zones.

Desired Outcomes: No net loss of floodplain storage.

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Metrics: Acres net floodplain fill

Minnehaha Creek Goal 13.1: Preserve the existing water storage capacity below the 100-year event elevation.

Action A. Minimize development below the 100-year event elevation. Action B. No net loss of the wetlands that provide upstream stormwater storage within this subwatershed. Action C. Evaluate dredging of sediment accumulated upstream of impoundments and control structures to maximize in-channel storage. Action D. Encourage the development and maintenance of depressional storage within the subwatershed. i. Promote the acceptability of minor flooding within the floodplain.

Minnehaha Creek Goal 13.2: Utilize District hydrologic and hydraulic data to identify potential public infrastructure high water impacts.

Action A. The HHPLS noted that the 100-year water level was expected to overtop several public streets and trails. Work together with the respective communities to determine specific impacts and potential improvements.

4.14 Recreation

Watershed Goal 14. Recreation. Promote the recreational use, where appropriate, of surface waters within MCWD by providing recreation opportunities for citizens by promoting the use and enjoyment of water resources with the intent of increasing the livability and quality of life within the watershed.

Discussion: There is considerable aquatic recreation in this subwatershed. The Chain of Lakes in Minneapolis attracts millions of users from across the Metro area, and Minnehaha Falls is known internationally. Minnehaha Creek is an urban canoe route enjoyed by many users. The District’s primary strategies in promoting and supporting recreational use of water resources is improving water quality in the lakes and managing water flows in the creek. The District is mindful that other public entities including cities and MPRB have historically maintained ownership of lands adjacent to many lakes and waterways throughout the subwatershed for the benefit of the public. The District is committed to working with local partners to address mutual goals. District and local efforts to improve ecological integrity and conserve corridors will enhance aesthetic and recreational values across the subwatershed.

Desired Outcomes: Manage surfaces waters to achieve water quality goals so designated use is maintained and unimpaired

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Metrics: • In-lake nutrient concentrations/Trophic State Index Scores (TSI) for the lakes in the subwatershed • Nutrient loading goals (lbs) for Minnehaha Creek and the lakes of the subwatershed • Macroinvertebrate Index of Biotic Integrity (M-IBI) in Minnehaha Creek • Stream Visual Assessment Protocol (SVAP) in Minnehaha Creek

Minnehaha Creek Goal 14.1: Support recreational use of Minnehaha Creek lakes in the subwatershed by reducing phosphorus and other pollutant loads and improving water quality.

Minnehaha Creek Goal 14.2: Manage Lake Minnetonka discharge to Minnehaha Creek in a way that balances desirable Lake Minnetonka and Minnehaha Creek levels with recreation and ecological impacts.

Action A. Continue to partner with the US Army Corps of Engineers and the DNR to explore options for adjusting the Grays Bay dam operating plan to balance maintenance of desirable Lake Minnetonka and Minnehaha Creek levels with recreation and ecological impacts.

Minnehaha Creek Goal 14.3: Coordinate with LGU’s and stakeholders to develop plans and corridors which balance recreational use and opportunities with water quality and ecosystem needs.

4.15 Erosion Control

Watershed Goal 15. Erosion Control. Control temporary sources of sediment resulting from land disturbance and identify, minimize and correct the effects of sedimentation from erosion-prone and sediment source areas.

Discussion: Erosion within the subwatershed can result in sediment being transported to lakes, wetlands, and streams, where it can degrade water quality and habitat. Sediment accumulating in channels, culverts, and other facilities can reduce their ability to convey stormwater, while erosion can undermine their stability.

The key areas identified in this plan for conservation activities include buffer zones adjacent to streams and channels. In some cases these buffer zones are riparian or flow-through wetlands, and those wetlands have been identified as key conservation areas. Where streams and channels flow through upland areas, conservation of native vegetation within these zones would also increase or maintain infiltration rates; decrease or maintain runoff rates and pollutant conveyance to water resources; and help minimize erosion. Restoration of lakeshore would have the same benefits. Identifying, addressing, and preventing erosion is necessary to meet District goals as well as to meet state and federal nondegradation, water quality and biological integrity requirements and to prevent the need for future TMDLs. The District acknowledges that given

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the urbanized nature of much of the watershed, success of District programs and projects is dependent on the participation and dedication of public and private partners towards achieving mutual goals.

Requiring new development and redevelopment to infiltrate some of the new stormwater generated would reduce post-development volumes downstream and help reduce future erosion in streams and channels; minimize new pollutant loading that would have been conveyed by that stormwater; and help maintain groundwater levels, preserving wetlands. Limiting discharges from subwatersheds and basins that are currently landlocked is necessary to prevent further degradation of downstream water quality as well as to limit new volumes discharged to channels that are already experiencing erosion.

The Minnehaha Creek Stream Assessment identified numerous localized areas of erosion on Minnehaha Creek. Strategies in the Minnehaha Creek subwatershed will focus on identifying erosion problems on a continuing basis, working with LGUs to correct them, and implementation of stream restoration programs to improve streambank stability.

Desired Outcomes: Reduction in pollutant loading of temporary and permanent nature from erosion to supplement other goals.

Metrics: • In-lake nutrient concentrations/Trophic State Index Scores (TSI) for the lakes in the subwatershed • Nutrient loading goals (lbs) for Minnehaha Creek and the lakes of the subwatershed • Macroinvertebrate Index of Biotic Integrity (M-IBI) in Minnehaha Creek • Stream Visual Assessment Protocol (SVAP) in Minnehaha Creek

Minnehaha Creek Goal 15.1: Identify and address erosion problems in the subwatershed.

Action A. Identify, inventory, and prioritize channel, shoreline and other erosion problems in addition to those already identified in the HHPLS and the Minnehaha Creek Stream Assessment. Action B. In collaboration with riparian cities and property owners, other agencies and infrastructure owners, restore degraded streambanks on Minnehaha Creek to achieve a Stream Visual Assessment Protocol mean score above 5.0 and other streams to stabilize streambanks; reduce pollutant loading, erosion and sediment transport; and increase habitat. Figure 20 illustrates areas identified in the Stream Assessment as high priorities for restoration. i. Periodically update the Minnehaha Creek stream assessment to assess current stream condition and ecological integrity. Action C. Work in partnership with creek riparian communities and other agencies and utilities to spot repair streambank erosion. Action D. Work cooperatively with the National Park Service and Minneapolis Park Board to identify necessary streambank restoration and structure

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improvements in the Mississippi River gorge from Minnehaha Falls to the Mississippi River. Action E. The HHPLS modeled higher than desirable velocities at several outfalls that could lead to erosion. Work cooperatively with the riparian cities to evaluate the need to provide erosion control or energy dissipation measures or reconstruct these outfalls to prevent erosion and downstream sediment transport. Action F. Inspect erosion-prone areas of Minnehaha Creek at least annually to assess their condition and inspect the entire creek at least every five years. Action G. Implement the regulatory and management goals identified in this plan. Action H. Regulate new development and redevelopment and ensure compliance with erosion control standards

Minnehaha Creek Goal 15.2: Manage streamside infrastructure to enhance stream stability.

Action A. Promote replacement of deteriorated streambank protection with bioengineered protections where practical and effective. Enhance existing boulder riprap protection with deep-rooted vegetation. Where improvements are made preserve only selected retaining walls and other streamside structures that are of historical significance. Action B. Protect other beneficial uses (infrastructure) of the streamside corridor from damage by streambank erosion. Action C. Promote other riparian zone uses such as streamside trails, with appropriate erosion protection and riparian vegetation enhancements. Action D. Work cooperatively with the adjacent property owners to prevent erosion and sediment transport and stabilize streambanks as necessary.

4.16 Regulation

Watershed Goal 16. Regulation. Promote effective planning to minimize the impact of development and land use change on water resources as well as achieve watershed District Goals.

Discussion: The District’s regulatory program is the means by which many of the goals enumerated here would be accomplished. As development and redevelopment occurs, property owners and developers are required to treat and control stormwater, limit impacts to wetlands, and meet other standards. Additional regulation may be necessary in the Minnehaha Creek subwatershed to implement the actions in this plan.

Desired Outcomes: Utilize regulatory program to cost-effectively manage land use to achieve other goals.

Metrics:

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• Acre-feet volume abstraction • In-lake nutrient concentrations/Trophic State Index Scores (TSI) for the lakes in the subwatershed • Nutrient loading goals (lbs) for Minnehaha Creek and the lakes in the subwatershed • Wetland quantity (acres)

Minnehaha Creek Goal 16.1: In consultation with LGUs through an appropriate rulemaking process, amend existing or adopt new rules to implement the actions identified here within two years of adoption of this plan.

Action A. Amend District rules as set forth in this Plan within two years of adoption of this plan. Action B. Provide technical assistance to LGUs in the implementation of existing or new rules. i. Develop and distribute model ordinances and design standards that could be used to implement existing or new rules. ii. Sponsor educational opportunities for LGU staff, developers, elected and appointed officials and other interested parties to provide practical information and opportunities for sharing experiences. iii. Promote “Conservation Ordinances” related to low-impact development, tree-conservation, open space conservation, etc.

4.17 Public Involvement

Watershed Goal 17. Public Involvement. Solicit input from the general public with the intent that policies, projects and programs will address local community values and goals as well as protect historic and cultural values regarding water resources; strive to manage expectations; base decisions on an educated public; foster an educated and informed public within the watershed.

Discussion: The District has good working relationships with the LGUs within the watershed, and maintains a Citizens Advisory Committee to obtain regular public input on issues of concern to the District and its citizens. As the District implements the actions identified in this plan, including the education and communication actions described above, it will be important to obtain direct input from water resource users. The primary strategy for the Minnehaha Creek subwatershed will be working with individuals, the cities and county and the National Park Service.

Desired Outcomes: Engage the public to encourage involvement in District activities and stewardship of area resources.

Metrics: Positive contacts with property owners and interest groups.

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Minnehaha Creek Goal 17.1: Work cooperatively with individuals, the cities and county and the National Park Service as necessary to obtain public involvement and input regarding Minnehaha Creek and its subwatershed.

Action A. Provide information and assistance as requested. Action B. Attend meetings as requested to share information, hear concerns, and maintain a good working relationship.

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5.0 Implementation Program

The goals set forth in Section 4.0, Resource Management Goals and Strategies will require an integrated set of programs and projects oriented toward the conservation and improvement of water resources within the watershed and identifies parties responsible for each activity. The following sections describe generally the activities that will be undertaken by various parties. Table 27 in Section 5.9 provides a cost estimate and schedule for the District’s responsibilities for new activities in the implementation program.

5.1 Regulatory Program

As discussed in Section 3.6 above, future development is not expected to contribute significant additional stormwater volume or phosphorus loads to Minnehaha Creek. However, an overall reduction in phosphorus loading from the subwatershed is desirable and additional reductions from regulation of pollutant loading and volume should be considered. Additional infiltration and minimization of new impervious surface should be encouraged to reduce pollutant loading from runoff, help restore base flow in the creek and reduce peak runoff rates. To decrease pollutant loading, control new volumes, encourage increased infiltration and provide for additional wetland management, additional regulation may be necessary. A decision on rulemaking needs/standards can only be made after the formal rulemaking process. In addition, further amendments to the Rules should not be precluded by the content of the plan.

Additional regulatory controls on permitted development and redevelopment will be considered for this subwatershed to increase phosphorus load reduction requirements, add volume management and infiltration requirements, implement wetland management in accordance with management classification, and increase scrutiny of development that may impact groundwater or key conservation resources. Regulations providing an incentive such as a volume reduction credit to developers to maintain undisturbed areas, reforest, or plant native vegetation may be considered.

The following are revised or additional regulatory controls in this subwatershed that would be necessary to assist the District in meeting the goals of this Plan:

1. Amend existing or establish new District rules requiring abstraction of the first one inch of rainfall on new permitted development and redevelopment. 2. Amend existing or establish new District rules requiring greater than 50 percent phosphorus removal on new permitted developments within the subwatershed 3. Amend District rules to incorporate a requirement for stormwater management plan approval prior to submittal of a preliminary plat. 4. Amend existing or establish new District rules requiring submittal of a functions and values assessment for all proposed wetland impacts requiring a permit; mitigation of all

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fill in Preserve category wetlands; and specifying by management classification stormwater discharge pretreatment, buffer, hydroperiod, and other wetland standards. 5. Establish new District rule requiring an additional level of analysis and review of permitted development and redevelopment where there is a potential to adversely impact groundwater connected to a surface water feature. 6. Require pretreatment of stormwater discharged to wetlands or infiltration areas in the areas of high aquifer sensitivity.

5.2 Land Conservation Program

The opportunity exists to create connections between ecosystems within the Lake Minnetonka subwatersheds and the Mississippi River to improve water quality, preserve natural conveyances, and facilitate the movement and proliferation of native species as well as enhance recreational opportunities. The District will prioritize Land Conservation Program activities in the Minnehaha Creek Subwatershed based on meeting one of the following criteria:

ƒ Connecting or expanding existing public lands; ƒ As part of a restoration project; or ƒ Leveraging redevelopment opportunities.

Figure 19 identifies priority areas in the watershed, the conservation of which will improve the characteristics of the aquatic ecosystem and the water quality within the subwatershed as well as areas downstream.

The District operates a Land Conservation Program that undertakes conservation activities ranging from assisting property owners in enrolling property in conservation programs to acquiring easements or fee title over high value resources. Some of the key conservation areas identified on Figure 19 are located within a current Land Conservation Program target area or have been proposed for addition to the target area. The District will continue to proactively investigate opportunities to conserve key resources within the Minnehaha Creek subwatershed, and will work cooperatively with other agencies and groups to accomplish this subwatershed’s conservation goals. The District will provide technical assistance to the LGUs to identify and implement strategies for local conservation efforts in support of program goals.

5.3 Education Program

The District operates a watershed-wide Strategic Education and Communications program that provides general information of wider interest as well as targeted information. The targeted education and public involvement activities identified in this plan will be implemented to assist in the reduction of existing pollutant loading to Minnehaha Creek, the lakes, and other water resources in the subwatershed as well as increasing infiltration within the subwatershed.

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5.4 Monitoring and Data Collection

Hydrologic Data Program. To monitor progress toward meeting water quality and quantity goals, routine monitoring of Minnehaha Creek will continue to be a part of the District’s annual Hydrologic Data program. Macroinvertebrate monitoring will be completed on Minnehaha Creek every five years. The District will continue to partner with the Minneapolis Park Board as it monitors water quality in the city lakes.

Aquatic Vegetation. Comprehensive aquatic vegetation data is available for many but not all the lakes within the subwatershed. The District will work in partnership with the Minneapolis Park Board and other local governments to obtain aquatic vegetation data and to develop vegetation management plans for those lakes.

Wetland Monitoring. Wetlands with exceptional value vegetation are present in the subwatershed. Because of the importance to overall subwatershed ecological integrity of preserving these values, these wetlands will be regularly monitored for invasive species by staff or trained volunteers or in cooperation with the Minneapolis Park Board.

5.5 Operations and Maintenance

Activities detailed in this implementation plan will require new operations and maintenance activities in this subwatershed. These include:

Table 14. Ongoing District operations and maintenance tasks in the Minnehaha Creek subwatershed. Task Spring Summer Fall Early Spring and After Storm Late Fall and After Inspect Erosion-Prone Reaches of Creek After Storm Storm Inspect High Vegetative Diversity Wetlands Regularly Regularly Regularly Inspect channel dredging project area for sediment Annually accumulation: West 44th Street to TH 100 Remove debris in Minnehaha Creek and other streams that As needed As needed As needed poses an obstruction to flow or causes flooding Inspect channel improvement project area for proper Annually operation: 300 feet upstream of TH 100

Table 15. Ongoing District operations and maintenance tasks for the Minnehaha Creek subwatershed canoe facilities. Responsible Task Spring Summer Fall Parties Routine Inspection MCWD After Snowmelt June September Debris and Trash Removal MCWD As needed As needed As needed Minor Erosion Repair MCWD As needed As needed As needed Temporary and Permanent Sign MCWD As needed As needed As needed Maintenance Fence and Barrier Maintenance MCWD As needed As needed As needed Portage and Landing Maintenance MCWD As needed As needed As needed

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Table 16. Ongoing District operations and maintenance tasks for previously completed Minnehaha Creek subwatershed improvement projects. Water Quality Structural Major Erosion Sediment Task Monitoring Repair Repair removal Twin Lakes Park Pond As Needed As Needed As Needed As Needed Cedar Meadows Pond As Needed As Needed As Needed As Needed Lake Calhoun Ponds As Needed As Needed As Needed As Needed Lake Nokomis Ponds As Needed As Needed As Needed As Needed Pamela Park Ponds As Needed

Table 17. Potential ongoing operations and maintenance tasks for proposed Minnehaha Creek subwatershed improvement projects. Treat- Wetland Stream Task ment Restor- Restor- Spring Summer Fall Ponds ations ations Early and Late and Routine Inspection D D D After Storm After Storm After Storm Vegetation Management D D As needed As needed As needed General Upkeep D D Regularly Regularly Regularly Debris and Trash D As needed As needed As needed Removal Inlet/Outlet Cleaning D D As needed As needed As needed Minor Erosion Repair D D D As needed As needed As needed Note: Responsible parties would be determined by negotiation at the time of project proposal

5.6 LGU Requirements

5.6.1 Local Government Unit Subwatershed Phosphorus Load Reductions

The HHPLS and the Lake Hiawatha TMDL have identified a need to reduce phosphorus loading to Minnehaha Creek to achieve a goal of an in-creek total phosphorus concentration of 80 ug/L. An approximate 8 percent load reduction was identified to be achieved through small-scale infiltration BMPs. The distribution of that load reduction is shown in Table 18 below. An additional 8 percent load reduction is identified to be achieved through near- and in-creek improvements. At this time, insufficient information is available regarding in-stream processes that might also be contributing to phosphorus concentrations, including streambank erosion, internal loading in the impoundment areas, and contributions from riparian wetlands. This plan recommends completion of a Minnehaha Creek Diagnostic Study to identify those internal sources and potential reductions from internal and streambank improvements prior to allocating that additional 8 percent load reduction to potentially collaborative construction projects as well as an additional allocation of phosphorus load reduction to upstream cities.

This plan promotes the general application of BMPs such as increased street sweeping, local water quality ponds, rain gardens and infiltration swales. The LGUs must annually report to the District their progress toward accomplishing this requirement.

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Table 18. Allocation of Minnehaha Creek subwatershed general small-scale infiltration practices load from lakes TMDL as LGU Phosphorus Load Reductions (lbs/yr). LGU Lake Hiawatha Lake Nokomis Diamond Lake Wayzata 3 Minnetonka 121 Plymouth 10 Hopkins 34 St. Louis Park 172 Edina 67 Golden Valley 2 Minneapolis 217* 24 62 Richfield 0 36 Ft. Snelling 0 6 TOTAL 626 66 62 *Includes 28 pound reduction in Lake Harriet lakeshed (see Table 19) and 22 pound reduction in Diamond Lake lakeshed, see Table 22.

5.6.2 Land Conservation

A key element in achieving overall ecological integrity goals in the Minnehaha Creek subwatershed is the conservation of key ecological areas, including high-value wetlands and connecting uplands, within the Minnehaha Creek corridor. LGUs must identify in their local water management plans the areas shown on Figure 19. The local plan must also identify strategies the LGU will undertake to protect the ecological values of those areas. These may include such strategies as land use regulation; acquisition and management; conservation easements; ecological restoration; and property owner education regarding land management strategies to maintain ecological integrity.

5.6.3 Other Issues

Landlocked Basins. There are existing land-locked subwatershed units and basins within this subwatershed that the cities have been considering for outlet drainage projects. To protect the quality of downstream resources, local plans must either no longer consider this an option, or demonstrate how this could be achieved without impact to downstream water quantity or quality impacts. Outletting will generally be discouraged unless there is a demonstrated threat to property structures or public safety.

5.7 Phosphorus Load Reduction

One of the water quality goals for this subwatershed is the reduction of phosphorus loading into the Creek and lakes that exceed their total phosphorus goal or that are subject to a TMDL load reduction requirement.

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Tables 19, 20, 21, 22 and 23 break down modeled phosphorus loading to each lake by source: atmospheric deposition, external sources, and internal sources. Atmospheric deposition is a regional issue and is not dealt with here. The primary means of addressing external loading are through the regulation of new loads generated by development and the reduction of existing loads from the subwatershed.

In some cases the phosphorus load contributed from the subwatershed is not sufficient to explain the current in-lake phosphorus concentration. The most likely sources for this discrepancy are internal loading from lake sediments or aquatic vegetation. Internal load management such as alum treatment to control sediment sources coupled with control of aquatic vegetation often helps to alleviate some internal loading. Rough fish management may also be required. A feasibility study would determine the most appropriate internal load reduction options.

Minnehaha Creek. The HHPLS identified a need to reduce phosphorus loading to Minnehaha Creek to achieve a goal of an in-creek total phosphorus concentration of 80 ug/L. See Section 5.6.1 for a discussion of load reduction strategies.

Brownie Lake. Brownie Lake is at or very near its phosphorus, chlorophyll, Secchi transparency, and TSI goals, and is not expected to change significantly due to development. The emphasis in the future will be on the prevention of degradation of water quality.

Cedar Lake. Cedar Lake is better than its phosphorus, chlorophyll, Secchi transparency, and TSI goals, and is not expected to change significantly due to development. The emphasis in the future will be on the prevention of degradation of water quality.

Lake of the Isles. Lake of the Isles meets or is better than its phosphorus, chlorophyll, Secchi transparency, and TSI goals, and is not expected to change significantly due to development. The emphasis in the future will be on the prevention of degradation of water quality.

Lake Calhoun. Lake Calhoun is better than its phosphorus, chlorophyll, Secchi transparency, and TSI goals, and is not expected to change significantly due to development. The emphasis in the future will be on the prevention of degradation of water quality.

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Lake Harriet. Lake Harriet water quality has been improving. Although the long-term average of 23 μg/L is still slightly higher than its total phosphorus goal of 20 μg/L, water quality is very good. Table 19 sets forth a summary plan for how load reductions could be accomplished.

Table 19. Phosphorus load reduction plan for Lake Harriet (Goal = 20 μg/L). Ultimate Phosphorus Planned Final Load Reductions Loading Source Reduction [lb/yr] [lb/yr] [lb/yr] Atmospheric Atmospheric deposition NA 85 NA 85 External Loads External load determined from modeling land use 543 Existing Regulations 21 LGU load allocation (Table 18) 28 Total After Reductions 494 Internal / "Unknown" Loads Internal/“unknown" loads determined from modeling land use 37 Internal load management 26 Total After Reductions 11 Total Load TOTAL 665 590 LOAD GOAL 562 Adaptive DIFFERENCE 28 management

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Lake Nokomis. A TMDL study including a phosphorus reduction plan is currently being developed for Lake Nokomis. Proposed reductions include: reductions due to the new prohibition on the use of fertilizer with phosphorus; proper operation of the Lake Nokomis weir; application of neighborhood-level BMPs to increase infiltration and treat stormwater; and internal load management. A diagnostic and feasibility study would be required to evaluate internal load management in more detail. Table 20 sets forth a summary plan for how load reductions could be accomplished, in accordance with the TMDL.

Table 20. Phosphorus load reduction plan for Lake Nokomis (Goal = 50 μg/L). Ultimate Phosphorus Planned Final Load Reductions Loading Source Reduction [lb/yr] [lb/yr] [lb/yr] Atmospheric Atmospheric deposition NA 49 NA 49 External Loads External load determined from modeling land use 453 Reductions Phosphorus free fertilizer 31 proposed in the Operate weir 104 draft TMDL General BMP load 66 reductions: sweeping, neighborhood BMPs, infiltration Regulation Existing regulations 13 Total After Reductions 239 Internal / "Unknown" Loads Internal/“unknown" loads determined from modeling land use 406 Internal load management 90 Total After Reductions 316 Total Load TOTAL 908 604 LOAD GOAL 599 DIFFERENCE 5

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Lake Hiawatha. A TMDL study including a phosphorus reduction plan is currently being developed for Lake Hiawatha. Lake Hiawatha receives direct inflow from Minnehaha Creek, and is greatly influenced by the creek’s water quality and the amount of flow, making developing specific load reductions difficult. Proposed reductions from the TMDL include: reductions due to the new prohibition on the use of fertilizer with phosphorus; construction of the proposed Hiawatha Golf Course ponds and other BMPs; application of neighborhood-level BMPs to increase infiltration and treat stormwater; reduction of phosphorus loading in Minnehaha Creek through streambank stabilization and buffer restoration; and other BMPs throughout the watershed such as increased street sweeping, retrofits of infrastructure, etc. Table 21 sets forth a summary plan for how the reductions could be accomplished, in accordance with the TMDL.

Table 21. Phosphorus load reduction plan for Lake Hiawatha (Interim Goal = 61 μg/L). Ultimate Phosphorus Planned Final Load Reductions Loading Source Reduction [lb/yr] [lb/yr] [lb/yr] Atmospheric Atmospheric deposition NA 15 NA 15 External Loads External load determined from modeling land use 10,917 Reductions Phosphorus free fertilizer 355 proposed in the Golf course, other ponds 46 Local projects draft TMDL Increase infiltration 626 Creek improvements 626 Other specific BMPs 53 Local prpojects Regulation Existing Regulations 302 Total After Reductions 8,909 Internal / "Unknown" Loads Internal/“unknown" loads determined from modeling land use 194 Internal load management ---- Total After Reductions 194 Total Load TOTAL 11,126 9,118 LOAD GOAL 10,038 DIFFERENCE (-920)

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Diamond Lake. A TMDL study including a phosphorus reduction plan is currently being developed for Diamond Lake. Proposed reductions from the TMDL to reach the lake’s interim goal of 90 ug/L include: reductions due to the new prohibition on the use of fertilizer with phosphorus; increased street sweeping; application of neighborhood-level BMPs to increase infiltration and treat stormwater; treatment of runoff from an industrial area in subwatershed MC-142; and lake biomanipulation to reduce internal loading. A diagnostic and feasibility study would be required to evaluate internal load management in more detail. Table 22 sets forth a summary plan for how load reductions could be accomplished in accordance with the TMDL.

Table 22. Phosphorus load reduction plan for Diamond Lake (Interim Goal = 90 μg/L). Ultimate Phosphorus Planned Final Load Reductions Loading Source Reduction [lb/yr] [lb/yr] [lb/yr] Atmospheric Atmospheric deposition NA 15 NA 15 External Loads External load determined from modeling land use 260 Phosphorus free fertilizer 26 General BMP load 84 Reductions reductions: sweeping, proposed in the neighborhood BMPs, draft TMDL infiltration Local projects MC-142 runoff 18 improvement Local project Regulation Existing regulations 15 Total After Reductions 121 Internal / "Unknown" Loads Internal/“unknown" loads determined from modeling land use 211 Internal load management 95 Total After Reductions 116 Total Load TOTAL 486 252 LOAD GOAL 265 DIFFERENCE (-13)

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Powderhorn Lake. A TMDL study including a phosphorus reduction plan is currently being developed for Powderhorn Lake. Proposed reductions from the TMDL to reach the lake’s interim goal of 90 ug/L include: reductions due to the new prohibition on the use of fertilizer with phosphorus; addition of a filtration system on the CDSs on the outfalls; increased street sweeping; application of neighborhood-level BMPs to increase infiltration and treat stormwater; and lake biomanipulation to reduce internal loading. A diagnostic and feasibility study would be required to evaluate internal load management in more detail. Table 23 sets forth a summary plan for how load reductions could be accomplished in accordance with the TMDL.

Table 23. Phosphorus load reduction plan for Powderhorn Lake(Interim Goal = 90 μg/L). Ultimate Phosphorus Planned Final Load Reductions Loading Source Reduction [lb/yr] [lb/yr] [lb/yr] Atmospheric Atmospheric Deposition NA 2 NA 2 External Loads External Load Determined from Modeling Land Use 126 Reductions Phosphorus free fertilizer 15 proposed in the Increased street sweeping 24 draft TMDL Increase infiltration 2 Filtration on CDSs 31 Regulation Existing Regulations - Total After Reductions 54 Internal / "Unknown" Loads Internal/“Unknown" Loads Determined from Modeling Land Use 139 Internal load management 104 Total After Reductions 35 Total Load TOTAL 267 91 LOAD GOAL 90 DIFFERENCE (-1)

5.8 Capital Improvement Program

Capital projects in the Minnehaha Creek subwatershed include stream restoration projects to repair erosion and improve habitat as noted in the Minnehaha Creek Steam Assessment; and projects to maintain existing infrastructure and improvements.

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These projects and others identified below will progress the District toward achieving its various goals for the subwatershed. This program is not a comprehensive list of all capital needs or potential projects within the subwatershed, and is limited by available financial resources and staff capacity to manage projects. These priority projects are intended to:

• Progress improvements to water quality as identified in the TMDLs for the lake in the subwatershed. • Stabilize, restore and improve biotic integrity reaches of Minnehaha Creek as identified in the Minnehaha Creek Stream Assessment. • Mitigate the impacts of development on downstream resources.

These proposed projects emphasize the achievement of multiple objectives. For example, stream restoration would not only stabilize streambanks and prevent further erosion, it would provide an opportunity to improve in-stream and buffer habitat, conserve existing high-value resources, and reduce sediment and nutrient transport downstream.

5.8.1 Minnehaha Creek Diagnostic Study/TMDL Project Minnehaha Creek Diagnostic Study and Biotic Integrity TMDL Description A study to identify in-stream processes that might be contributing to phosphorus concentrations in the creek and in Lake Hiawatha as well as stressors that might be contributing to impaired biological integrity in Minnehaha Creek. Need This study is part of the effort to prepare and/or implement two Total Maximum Daily Load (TMDL) studies for water resources in the Minnehaha Creek subwatershed. Lake Hiawatha, which is in-line to Minnehaha Creek, has been designated by the MPCA and EPA as an Impaired Water for excess nutrient concentrations that lead to excessive algae blooms and poor water clarity. Phosphorus transported by Minnehaha Creek is the primary source of those excess nutrients. To help achieve Lake Hiawatha water quality goals, the Hiawatha TMDL study estimated that the total phosphorus load from nonpoint sources in the watershed must be reduced by at least eight percent and the load contributed from near- and in-stream processes to be reduced by an additional eight percent. This Diagnostic Study would identify in-stream processes that might be contributing to phosphorus concentrations in the creek and in Lake Hiawatha, including streambank erosion, internal loading in the impoundment areas, and contributions from riparian wetlands. This study would also identify potential reductions from internal and streambank improvements as a means of determining what part of the eight percent load reduction allocated to near- and in-stream improvements can actually be achieved, and whether additional watershed load reductions would be necessary to meet overall phosphorus reduction goals.

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Minnehaha Creek itself has been designated an Impaired Water because of its impaired biologic community. Many of the processes that the Diagnostic Study will evaluate are also likely stressors to the biotic community. Combining the Diagnostic Study and Biotic Integrity TMDL would be efficient and would provide for the coordination of implementation efforts. For example, streambank erosion is often a contributor of sediment and phosphorus loading downstream. Biostabilization with native vegetation reduces that pollutant source while improving fish and macroinvertebrate habitat.

Outcome An implementation plan identifying the most effective suite of projects to reduce phosphorus and sediment loading and to restore ecological integrity Estimated Diagnostic and TMDL study. The District has $150,000 Cost and received a grant from the MPCA to complete this Funding study in 2006-2007. Schedule 2006

5.8.2 Minnehaha Creek Stream Restoration The 2003 Minnehaha Creek Stream Assessment identified numerous areas of erosion along the length of the creek, as well as a general lack of steam complexity and lack of habitat for macroinvertebrates and fish largely driven by stream aggradation in impounded areas often upstream of artificial grade controls. Based on these stressors and its flow regime Minnehaha Creek has been designated by the State as an Impaired Water for fish communities. Minnehaha Creek is also listed as impaired for chlorides, dissolved oxygen, and bacteria (E. Coli). The Minnehaha Creek Visioning Partnership identified erosion control, the improvement of conditions for aquatic life, and the improvement of aesthetic appearance as high priorities for future creek corridor management. In 2012 the District completed a second Stream Assessment to evaluate the geomorphology and ecological health changes over time. The 2012 Stream Assessment identified a general need for additional projects beyond those identified in the 2007 capital improvement program. General recommendations for improving the ecological integrity, natural aesthetic and recreational value of Minnehaha Creek include but are not limited to: removing or modifying grade controls to allow fish passage and a more natural hydrologic condition; preserving and expanding wooded/vegetated riparian buffers along the entire stream length; reconstructing or remeandering channel and floodplain where space allows to improve geomorphic/hydrologic form and function and in-stream habitat; stabilizing banks using bioengineering techniques; establishing areas to preserve and enhance view-sheds; and establishing recreational corridor connectivity through passive uses such as trails and vistas.

Over the planning period the District will partner with riparian cities, property owners, other agencies, and infrastructure owners to accomplish stream restoration projects that will meet multiple objectives for water quality, biotic improvement, education and recreation. Stream restoration projects would enhance riparian corridor vegetation; stabilize streambanks through

Amendment Effective Date: Minnehaha Creek Subwatershed Page 81 June 27, 2013 bioengineering; add fish and macroinvertebrate habitat; create pool-riffle complexes; incorporate woody debris; remove select grade controls; and enhance educational and recreational opportunities through the creation of vistas and trail corridors designed to complement and protect the stable and restored streambank environment.

The CIP includes proposed improvements to several high-priority reaches as identified in the 2003 Minnehaha Creek Stream Assessment. Priority reaches are those where stream restoration could improve streambank stability to “Good” as measured by Pfankuch stability rating relative to Rosgen stream type, or those where the Stream Visual Assessment Protocol (SVAP) mean score could be improved to 5.0 or better, or by one full point. Specific improvements are guided and refined by the results of the Minnehaha Creek Diagnostic Study, the Minnehaha Creek Biotic Integrity TMDL, the 2003 Minnehaha Creek Stream Assessment, the findings of the Minnehaha Creek Visioning Partnership, the 2012 Minnehaha Creek Stream Assessment, opportunities for partnership, future studies, and individual reach needs and opportunities. Figure 20 illustrates the location of priority reaches based on the 2003 Stream Assessment. Not all of these reaches were prioritized in the 2007-2017 CIP. Those that were not included are Reach 2, Reach 11, Reach 18, and Reach 29. The list of specific reaches below reflects priorities determined based on available data to date. However, over the term of this plan, the District: (a) may shift funds between projects included under 5.8.2 to reflect immediate priorities and work scheduling decisions; and (b) may identify and implement projects within other reaches or incorporate project elements consistent with the goals of 5.8.2, on determining that those goals will be met and pursuant to the procedures described below. There are two reasons for the District to reserve this ability to adjust project implementation on the basis of its ongoing review:

(a) The District’s technical understanding of subwatershed hydrology and the hydraulic behavior of Minnehaha Creek will continue to develop and thereby refine the District’s capacity to determine where and what sorts of improvements will be most cost-effective. The ongoing work described on the preceding page and similar ongoing diagnostic work likely will identify additional sites that merit attention during the planning period.

(b) The Minnehaha Creek corridor is fully developed and land prices are high. The riparian edge is intensively used by private homeowners and commercial/industrial uses in the upper corridor and by the public on Minneapolis Park and Recreation Board (MPRB) lands within the lower corridor. Stream restoration methods may impede intensive use and involve concepts and aesthetics for which there is not yet universal acceptance. Securing landowner participation or easements for stream work is an uncertain prospect, or project opportunities may arise in an unanticipated way and subject to the property owner’s timeline. Other opportunities may occur in the context of public road or utility work similarly driven by third-party time constraints. The District accordingly must be prepared to respond to these opportunities.

Accordingly, the District intends to plan for and pursue implementation within the specific reaches enumerated below while also retaining the flexibility to pursue other opportunities as they arise. With respect to the latter, there will be several project development elements to ensure transparency and public accountability:

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(a) The District will continue to coordinate with the Cities of Minneapolis, Edina, St. Louis Park, Hopkins and Minnetonka and the MPRB to develop a more detailed understanding of hydrologic conditions in the subwatershed and Creek hydraulics and to confirm priority sites that meet District and municipal priorities. A focused feasibility study will be prepared for significant implementation actions to examine feasibility and cost-effectiveness. The study will be made publicly available and presented to the Board of Managers at a public meeting with the availability for public comment.

(b) As described earlier in this plan, each year, for budget and levy purposes, the District will review the status of its capital program in a public forum with opportunity for public input. Proposed revisions to the District’s 10-year CIP will be provided to Hennepin and Carver Counties and all cities wholly or partly within the District. At its budget and levy hearing, the District Board of Managers will make budgeting decisions that will set overall parameters for spending under this capital project 5.8.2 and set specific project implementation priorities for the upcoming fiscal year.

(c) Before expending levied funds on designing or implementing a restoration activity, the Board will distribute design plans and provide public notice for a public hearing and project ordering in accordance with Minnesota Statutes §103B.251. If the proposed work will exceed $300,000, the District will afford the additional procedures set forth in section 6.8 of the watershed plan (page 84).

Project Reach 4 Restoration Description Streambank restoration, buffer reestablishment, enhancement of in-stream habitat features Need This reach extends from 34th Avenue South to the Lake Hiawatha outlet weir. It contains a number of storm sewer outfalls that require repair or improvement. The riparian corridor is mostly turf grass maintained to an eroding creek edge. The reach scored a 4.1 on the Stream Visual Assessment Protocol index evaluated as part of the Minnehaha Creek Stream Assessment, mainly due to poor condition riparian zone resulting in streambank undercutting and instability. The reach includes spawning habitat, but lacks complexity of habitat features necessary to maintain a fish community. The project would focus on improving the streambank stability and quality of the riparian area through bioengineering and native vegetation plantings as well as installation of in-stream habitat features. Outcome Stabilized streambanks with both hard armoring and bioengineering to reduce erosion; improved riparian zone with native vegetation; improved fish and macroinvertebrate habitat; improvement in SVAP index to a score greater than 5.0.

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Estimated Design, construction, project management, $944,100 Cost and vegetation management contract. Funding source Funding for this project is the District capital levy. Schedule 2013 Design, cooperative agreement 2014 Construction

Project Reach 6 Restoration Description Streambank restoration, buffer reestablishment, enhancement of in-stream habitat features Need This reach extends from the Hiawatha Golf Course bridge to the Lake Nokomis outlet, and flows through the Hiawatha Golf Course. The riparian corridor is turf grass maintained to an eroding creek edge, with some riprap and a planted bank in one location. The reach scored an extremely poor 2.9 on the Stream Visual Assessment Protocol index evaluated as part of the Minnehaha Creek Stream Assessment, due to a poor condition riparian zone and lack of fish and invertebrate habitat. The project would focus on improving the streambank stability and quality of the riparian area through bioengineering and native vegetation plantings that would not adversely impact play on the golf course. Outcome Stabilized streambanks with bioengineering to reduce erosion; improved riparian zone with native vegetation; improved fish and macroinvertebrate habitat; improvement in SVAP index to a score greater than 5.0 or at least one full point better than existing. Estimated Design, construction, project management, $451,000 Cost vegetation management contract. Funding source for this project is the District capital levy. Schedule 2014 Design, cooperative agreement 2015 Construction

Project Reach 7 Restoration

Description Streambank restoration, buffer reestablishment, enhancement of in-stream habitat features Need This reach extends from Lake Nokomis to Bloomington Avenue South. It is channelized and stabilized with hard armoring. A portion of this reach has been reconstructed with restored meanders and bioengineered banks. The reach contains some erosion sites that require repair or improvement, including an exposed gas pipeline and a large box culvert whose discharge is creating erosion on the opposite bank. The riparian habitat is poor, with

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Project Reach 7 Restoration

some tree and shrub canopy and a narrow buffer of unmowed grass. The reach scored a 4.8 on the Stream Visual Assessment Protocol index evaluated as part of the Minnehaha Creek Stream Assessment, mainly due to poor condition riparian zone and the altered channel. The reach includes some fish habitat, but weirs and riprapped channels likely serve as passage barriers. The project would focus on improving the streambank stability and quality of the riparian area through bioengineering and native vegetation plantings as well as installation of in-stream habitat features. The project would also evaluate the replacement of existing grade controls with a meandered, stepped pool design to improve habitat and eliminate barriers to fish movement.

Outcome Stabilized streambanks with both hard armoring and bioengineering to reduce erosion; improved riparian zone with native vegetation; improved fish and macroinvertebrate habitat; improvement in SVAP index to a score greater than 5.0, or an improvement of one full point. Estimated Design, construction, project management, vegetation $654,800 Cost and management contract. Funding source for this project is Funding the District capital levy.

Schedule 2011 Design, cooperative agreement 2012 Construction

Project Reach 8 Restoration Description Streambank restoration, buffer reestablishment, enhancement of in-stream habitat features Need This reach extends from Bloomington Avenue to Portland Avenue S. It is an unstable channel with active cutting and deposition. It contains a number of erosion sites that require repair or improvement, including an exposed gas pipeline. The riparian corridor is mostly turf grass maintained to an eroding creek edge, although there are areas of the reach with good riparian woody vegetation. Some streambank has been stabilized with hard armoring. The reach scored a 5.8 on the Stream Visual Assessment Protocol index evaluated as part of the Minnehaha Creek Stream Assessment, mainly due to poor condition riparian zone resulting in streambank undercutting and instability. The reach has few fish habitat features. The project would focus on improving the streambank stability and quality of the riparian area through bioengineering and native vegetation plantings as well as installation of in-stream habitat features.

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Project Reach 8 Restoration Outcome Stabilized streambanks with bioengineering to reduce erosion; improved riparian zone with native vegetation; improved fish and macroinvertebrate habitat; improvement in SVAP index to a score greater than 6.0. Estimated Design, construction, project management, $967,600 Cost and vegetation management contract. Funding source Funding for this project is the District capital levy. Schedule 2007 Design, cooperative agreement 2007 Construction

Project Reach 9 Restoration Description Streambank restoration, buffer reestablishment, enhancement of in-stream habitat features Need This reach extends from Portland Avenue to Nicollet Avenue S. The riparian corridor is mostly turf grass maintained to an eroding creek edge in some portions of the reach and a healthy riparian forest in others. The reach includes fish spawning habitat. The reach scored a 5.6 on the Stream Visual Assessment Protocol index evaluated as part of the Minnehaha Creek Stream Assessment, mainly due to the areas of poor condition riparian zone resulting in streambank undercutting and instability. There are several locations where falling brick walls, riprap, culvert inlets, and improperly placed riprap are causing streambank erosion issues. The project would focus on improving the streambank stability and quality of the riparian area through bioengineering and native vegetation plantings. Outcome Stabilized streambanks with both hard armoring and bioengineering to reduce erosion; improved riparian zone with native vegetation; improvement in SVAP index to a score greater than 6.0. Estimated Design, construction, project management, $877,700 Cost and vegetation management contract. Funding source Funding for this project is the District capital levy. Schedule 2014 Design, cooperative agreement 2015 Construction

Project Reach 12 Restoration Description Streambank restoration, buffer reestablishment, enhancement of in-stream habitat features

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Need This reach extends from Logan Avenue S to 54th Street. It contains a number of storm sewer outfalls that require repair or improvement. The riparian corridor is mainly turf grass maintained to an eroding creek edge and with some areas of stable banks with riparian tree and shrub growth. The reach scored a 3.8 on the Stream Visual Assessment Protocol index evaluated as part of the Minnehaha Creek Stream Assessment, mainly due to the poor riparian conditions and resulting unstable banks. The reach includes areas with moderate in-stream fish habitat. During the stream assessment, fish spawning was observed throughout the reach. The project would focus on improving the streambank stability and quality of the riparian area through bioengineering and native vegetation plantings. Outcome Stabilized streambanks with both hard armoring and bioengineering to reduce erosion; improved riparian zone with native vegetation; improved fish and macroinvertebrate habitat; improvement in SVAP index to a score greater than 5.0, or an increase of one full point. Estimated Design, construction, project management, $1,380,100 Cost and vegetation management contract. Funding source Funding for this project is the District capital levy. Schedule 2015 Design, cooperative agreement 2016 Construction

Project Reach 14 Restoration Description Streambank restoration, buffer reestablishment, enhancement of in-stream habitat features Need This reach extends from France Avenue S to 54th Street West. Much of the riparian corridor is turf grass maintained to an eroding or riprapped creek edge, but the upper 900 feet is wooded. The reach scored a 5.8 on the Stream Visual Assessment Protocol index evaluated as part of the Minnehaha Creek Stream Assessment, mainly due to areas with poor- quality riparian vegetation. The project would evaluate construction of in- steam habitat features and options for improving the riparian zone with native vegetation buffers. Outcome Stabilized streambanks with both hard armoring and bioengineering to reduce erosion; improved riparian zone with native vegetation; improved fish and macroinvertebrate habitat; improvement in SVAP index to a score greater than 6.0. Estimated Design, construction, project management, $896,000 Cost and vegetation management contract. Funding source Funding for this project is the District capital levy.

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Schedule 2011 Design, cooperative agreement 2012 Construction

Project Reach 19-21 Restoration Description Streambank restoration, buffer reestablishment, enhancement of in-stream habitat features Need This reach extends from Meadowbrook Lake to Lake Street NE. The reach has been channelized and straightened. Where the Creek flows through Meadowbrook Golf Course, turf grass is maintained to steam edge. The riparian corridor is a mix of turf grass and stable banks with riparian tree and shrub growth. The reach scored a 7.0 on the Stream Visual Assessment Protocol index evaluated as part of the Minnehaha Creek Stream Assessment, mainly due to fish barriers and lack of fish habitat, although spawning was observed during the assessment. The project would evaluate the replacement of existing grade controls with a meandered, stepped pool design to improve habitat and eliminate barriers to fish movement. Improvement of the riparian zone could include reforestation and establishment of native vegetation buffers. Outcome Stabilized streambanks with both hard armoring and bioengineering to reduce erosion; improved riparian zone with native vegetation; improved fish and macroinvertebrate habitat; improvement in SVAP index to a score greater than 7.0. Estimated Design, construction, project management, $1,203,400 Cost and vegetation management contract. Funding source Funding for this project is the District capital levy. Schedule 2009 Design, cooperative agreement 2010 Construction

Overall Implementation Estimate (planning period): $7,374,700

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5.8.3 Minnehaha Falls/ Glen Restoration Project Minnehaha Falls/ Glen Restoration Description Streambank restoration, repair or replacement of retaining walls, buffer reestablishment, enhancement of in-stream habitat features Need A number of the retaining walls constructed by the Works Progress Administration and the Civilian Conservation Corps have deteriorated and are in need of restoration or replacement. Other needs for improvement in the area include trail and bridge abutments and correction of an ongoing drainage issue that is causing deterioration of the public safety access road to the Creek mouth. The District will work collaboratively with the Minneapolis Park and Recreation Board and the National Park Service to identify and construct improvements. The specific share of construction cost as well as ongoing maintenance costs associated with these improvements would be determined by cooperative agreement prior to implementation of this project. Outcome Protection of public health and safety; stabilized streambanks with both hard armoring and bioengineering to reduce erosion; improved riparian zone with native vegetation; improved fish and macroinvertebrate habitat. Estimated Phase I: Feasibility study $104,000 Ph I Cost and Phase II: Construct cooperative improvements. $3,183,232 Ph II Funding Funding source for this project is the District $3,287,232 Total capital levy. The specific share of construction cost as well as ongoing maintenance costs associated with these improvements would be determined by cooperative agreement prior to implementation of this project. Schedule 2007 Design, cooperative agreement 2008 Construction

5.8.4 Lake Nokomis Internal Load Management Project Lake Nokomis Internal Load Management

Description Design and implementation of strategies to reduce internal phosphorus loading, including: feasibility study; aquatic vegetation survey update and management plan; fishery survey update and management plan; biomanipulation strategies that may include aquatic vegetation management, zooplankton community and fishery manipulation, and chemical treatment.

Need A TMDL study including a phosphorus reduction plan is currently being

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developed for Lake Nokomis. Proposed reductions include control of external sources of phosphorus through various efforts in the watershed and internal load management.

Strategies may include aquatic vegetation management, biomanipulation and fishery management, or chemical treatment. The specific share of construction cost as well as ongoing costs associated with this project would be determined by cooperative agreement prior to implementation of this project.

Outcome Reduction in phosphorus load from internal sources estimated at 90 pounds annually; improved water clarity; more diverse aquatic vegetation community; improved aesthetics.

Estimated Investigation, permitting, implementation, and $30,600 Feasibility Cost project management. The District’s final cost $311,500 Implement share and any ongoing maintenance $342,100 Total responsibilities would be determined by the negotiation of a cooperative agreement with the city of Minneapolis and Minneapolis Park and Recreation Board.

Schedule 2007 Fish, vegetation, and zooplankton surveys, development of management plans, cooperative agreement 2007 Implementation of strategies

5.8.5 Regional Volume and Load Reduction Project Minnehaha Creek Regional Volume and Load Reduction Description Implementation of opportunities to reduce stormwater volumes and nutrient loading, including but not limited to construction of infiltration basins and devices, wetland restoration, reforestation, revegetation, and stormwater detention or redirection. Need The Minnehaha Creek-Lake Hiawatha TMDL draft report (March 25, 2013) identifies the need to reduce phosphorus and bacterial (E. coli) loading to meet water quality targets for Lake Hiawatha and Minnehaha Creek. The TMDL draft report calls for a reduction of 1,907 lbs/year throughout the subwatershed in order for Lake Hiawatha to meet an in-lake nutrient concentration of 50 ug/L. The TMDL draft report also identifies a need to reduce bacterial (E. coli) loading in order to meet the standard of 126 organisms/100 ml. At this time with our current understanding, the best

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Project Minnehaha Creek Regional Volume and Load Reduction approaches for addressing excess bacteria loads appear to be source reduction or volume control practices.

In addition, the 2003 Minnehaha Creek Stream Assessment identified two major issues impacting water quality and biotic integrity in the Creek: flashy storm event flows that often result in streambank erosion; and low base flows, which reduce habitat and limit biotic integrity. The high percent of impervious surface in this urbanized subwatershed has reduced the amount of stormwater that naturally infiltrates to surficial groundwater and which helps sustain base flow. This stormwater is efficiently conveyed to the creek through stormsewers, which results in the flashy flows.

The Stream Assessment analyzed options for reducing peak discharges in Minnehaha Creek, and identified 11 key subwatersheds where reduction of peak discharge from the subwatersheds would collectively result in the greatest reduction in peak discharge in the Creek. In these 11 subwatersheds, hypothetical ponds reducing peak discharge by 75 percent would result in a 27 percent reduction in Creek discharge at Cedar Avenue. Regional infiltration or other abstraction or detention focused on those subwatershed units would have the most impact on reducing peak flows in Minnehaha Creek.

Specific project locations and methods will be identified and implemented to reduce nutrient and bacterial loading to Minnehaha Creek and thus to Lake Hiawatha; decrease peak discharge rates in Minnehaha Creek to reduce streambank erosion; and increase baseflow in the Creek to improve its biotic integrity. These projects are intended to reduce annual volume and peak flows discharged to the Creek; increase infiltration to surficial groundwater; and reduce nutrient and bacterial export to the Creek.

Identifying specific implementation sites under this capital project element will be an ongoing process informed by refined technical knowledge of pollutant sources and geomorphological phenomena, available land and willing public or private partners. Priorities are set foremost by diagnosing the spatial distribution of pollutant loading to Minnehaha Creek.

For example, on the basis of available data, subwatershed units between West 34th Street and Excelsior Boulevard are the source of greatest phosphorus loading to Minnehaha Creek, both in absolute amount and on a unit area basis. Unit area loads for each subwatershed unit are determined by dividing the total phosphorus increase for each subwatershed unit by the area.

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Project Minnehaha Creek Regional Volume and Load Reduction The list of specific implementation sites below reflects priorities determined based on available data to date. However, over the term of this plan, the District: (a) may shift funds between projects included under 5.8.5 to reflect immediate priorities and implementation decisions; and (b) may identify and implement projects at other locations as well, on determining that the goals of 5.8.5 will be met and pursuant to the procedures described below. There are three reasons for the District to reserve this role for its ongoing review:

(1) The District’s technical understanding of subwatershed hydrology and the hydraulic behavior of Minnehaha Creek will continue to develop and thereby refine the District’s capacity to determine where and what sorts of improvements will be most cost-effective. For instance, in 2011 the MCWD and the Mississippi Water Management Organization awarded a Joint Watershed Research Grant to the University of Minnesota to study stream base flow in Minnehaha Creek. The focus of the research is on investigating whether stormwater runoff can be infiltrated and stored in the shallow aquifer to contribute to stream base flow in Minnehaha Creek during periods of low flow and drought conditions. This study is ongoing and could help inform preferred locations for infiltration.

(2) Metropolitan area municipalities and the Minneapolis Park and Recreation Board (MPRB) are key District partners. Municipalities are implementing their own comprehensive land use plans. They are subject to legal obligations to reduce annual stormwater volumes and pollutant loadings, and to manage stormwater in ways that may be compatible with District objectives or which may be in conflict with them.

For example, the City of Minneapolis is obligated by the Metropolitan Council Environmental Services to reduce stormwater that enters the sanitary sewer system. Actions such as disconnecting rooftop rain leaders from the sanitary system and completing the separation of combined sewers may increase the volume of annual stormwater runoff in the subwatershed, or may create or exacerbate local flooding issues. Other LGUs in the subwatershed are required, under the Nondegradation requirement of their NPDES Phase II permits, to reduce annual stormwater volumes to at least 1988 volumes.

The District endeavors to work very closely with these public partners and is committed to investing funds where they will best serve the combined needs of involved public entities. For this reason, the District needs to be prepared to be responsive to municipal needs and partnership interests as they evolve and arise.

(3) The Minnehaha Creek subwatershed is fully developed, land use is

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Project Minnehaha Creek Regional Volume and Load Reduction intensive and land prices are high. For these reasons, the District must be opportunistic with respect to siting opportunities. Opportunities may arise in conjunction with private redevelopment, public road reconstruction, MPRB capital work and other situations in which the opportunity occurs unexpectedly and is subject to the partner’s often-constrained timeline.

Accordingly, the District intends to plan for and pursue implementation within the specific drainage areas enumerated below while also developing and pursuing other opportunities as they arise. With respect to the latter, there will be several project development elements to ensure transparency and public accountability:

(a) The District will continue to work in partnership with the LGUs in the subwatershed to complete a more detailed study of the hydrologic and hydraulic conditions in the subwatershed to determine how District and LGU objectives can best be reconciled and advanced through partnership projects. For example, the District currently is working in coordination with the cities of Hopkins, St. Louis Park, Edina and Minneapolis and the MPRB to explore opportunities to partner on the regional treatment of stormwater runoff volumes and loads within priority subwatersheds. The City of Minneapolis has identified three specific priority projects for review and consideration for partnership with the District. The cost share between project partners would be determined during the development of feasibility studies for each project. These are:

• Flood area 29-30, located in subwatershed unit MC-129. This area drains to Lake Harriet, but has been considered in the past for redirection of some flow to the Creek. If the volume and load reduction study identifies this as a feasible option, it may be possible to coordinate improvements to manage stormwater in that area with the stream restoration project already identified for Reach 12. The estimated total cost of this project is $7.4 million.

• Flood area 26 “C”, located in subwatershed unit MC-147. Stormwater ponding and storm sewer upgrades are being considered for this third phase of projects in this flood area. The estimated total cost of this project is $1.8 million.

• Flood area 21-22, located in subwatershed unit MC-170. This area is in the direct drainage area of Lake Hiawatha, and includes stormwater upgrades and combined sewer separation projects.

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Project Minnehaha Creek Regional Volume and Load Reduction The estimated total cost of this project is $7.8 million.

For any significant implementation actions, whether the District pursues it in partnership or otherwise, a focused feasibility study will be prepared to examine feasibility and cost-effectiveness. The study will be made publicly available and presented to the Board of Managers at a public meeting with the availability for public comment.

(b) As described earlier in this plan, each year, for budget and levy purposes, the District will review the status of its capital program in a public forum with opportunity for public input. Proposed revisions to the District’s 10-year CIP will be provided to Hennepin and Carver Counties and all cities wholly or partly within the District. At its budget and levy hearing, the District Board of Managers will make budgeting decisions that will set overall parameters for spending under this capital project 5.8.5 and set specific project implementation priorities for the upcoming fiscal year.

(c) Before expending levied funds on the design or construction of an implementation action, the Board will distribute design plans and provide public notice for a public hearing and project ordering in accordance with Minnesota Statutes §103B.251. If the proposed work will exceed $300,000, the District will afford the additional procedures set forth in section 6.8 of the watershed plan (page 84).

Outcome Minimized new pollutant loads conveyed by runoff and generated within Minnehaha Creek; minimized new volumes generated by new development; protection of stream base flows and wetland and surficial groundwater hydrology; wetland restorations; conservation of high-value native vegetation and habitat. Estimated Minnehaha Creek Subwatershed Volume and Load $200,000 Cost Reduction Study Project 1: Improvements in MC-129. Funding $2,299,800 source is City of Minneapolis and District capital levy. Project 2: Improvements in MC-147. Funding $3,533,000 source is City of Minneapolis and District capital levy. Project 3: Improvements in MC-170. Funding source $2,440,600

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is City of Minneapolis and District capital levy. Project 4: Improvements in MC-58. Funding source $435,200 is District capital levy. Project 5: Improvements in MC-70-75. Funding $487,600 source is District capital levy. Project 6: Improvements in MC-95. Funding source $2,221,500 is District capital levy. Project 7: Improvements in MC-97. Funding source $1,504,500 is District capital levy. Project 8: Improvements in MC-134. Funding source $485,400 is District capital levy. Project 9: Improvements in MC-135. Funding source $1,340,200 is District capital levy. Project 10: Improvements in MC-139. Funding $511,000 source is District capital levy. Project 11: Improvements in MC-140. Funding $1,493,400 source is District capital levy. Project 12: Improvements in MC-146. Funding $564,300 source is District capital levy. Project 13: Improvements in MC-150. Funding $362,100 source is District capital levy. Project 14: Improvements in MC-151. Funding $524,700 source is District capital levy. Project 15: Improvements in MC-152. Funding $678,500 source is District capital levy.

Overall Implementation Estimate: $19,081,800 Schedule 2008: Complete volume and load reduction study 2008: Identify and construct improvements in MC-129 2009: Identify and construct improvements in MC-147 2011: Identify and construct improvements in MC-170 2012: Identify and construct improvements in MC-134 2013: Identify and construct improvements in MC-95 2014: Identify and construct improvements in MC-97 2015: Identify and construct improvements in MC-146 2015: Identify and construct improvements in MC-70-75 2016: Identify and construct improvements in MC-58

Amendment Effective Date: Minnehaha Creek Subwatershed Page 92-A June 27, 2013

Unscheduled: Identify and construct improvements in MC-152, MC-139, MC-150, MC-135, MC-140, MC-151; identify and construct improvements otherwise developed through described procedures.

5.8.6 Land Conservation

Project Minnehaha Creek Subwatershed Land Conservation Activities Description Implementation of Land Conservation program activities in the Minnehaha Creek subwatershed, including but not limited to acquisition of conservation easements or fee title to land as well as facilitating partnerships, encouraging conservation planning and activities, providing technical assistance, and education and outreach. Need The Land Conservation Program is an integral strategy to achieving the goals in this subwatershed plan. Land conservation activities help to maintain and improve ecologic integrity, surface and groundwater quantity and quality, wetlands integrity, and streambank stability. High priority areas are located in this subwatershed, including areas with high ecological values. Conservation of key land cover types may be beneficial to reducing runoff and associated pollutant transport, preserving high-infiltration areas,

Amendment Effective Date: Minnehaha Creek Subwatershed Page 92-B June 27, 2013

Project Minnehaha Creek Subwatershed Land Conservation Activities conserving native vegetation, conserving habitat and natural resource corridors, and improving ecologic integrity. Outcome Minimized new pollutant loads conveyed by runoff; protection of wetland and surficial groundwater hydrology; wetland restorations; conservation of high-value native vegetation and habitat. Estimated Estimated cost to achieve conservation goals in the $4,215,000 Cost and Minnehaha Creek subwatershed 2007-2017 District capital levy Funding Schedule Implement both proactively and as opportunities arise during the period 2007-2017

5.8.7 Browndale Dam Scour Repair Project Browndale Dam Scour Repair Description Restore eroded base of dam and scour hole to prevent future structural damage Need The Browndale Dam is a historic structure that lies at the outlet of the Mill Pond in the City of Edina. During the Plan Review process, the City of Edina solicited the involvement of MCWD in addressing erosion and scour issues occurring at the base of the dam. The City has proposed to design and implement structural improvements to counteract undercutting of the dam sill and stabilize a large scour hole at the downstream base of the structure. The District will work collaboratively with the City of Edina construct improvements. The specific share of construction cost as well as ongoing maintenance costs associated with these improvements would be determined by cooperative agreement prior to implementation of this project. Outcome Protection of public health and safety; stabilized streambed to reduce erosion Estimated Funding source for this project is the District $50,500 Cost and capital levy. The specific share of construction cost Funding as well as ongoing maintenance costs associated with these improvements would be determined by cooperative agreement prior to implementation of this project.

Schedule 2007 Design, cooperative agreement 2008 Construction

April 2007 Minnehaha Creek Subwatershed Page 93

5.8.8 Maintenance Projects The District is responsible for sediment removal from several ponds in the subwatershed. Sediment has been recently removed from some of these ponds. They should be surveyed in 2008 to determine if maintenance is necessary.

Table 24. Estimated pond maintenance costs in the Minnehaha Creek subwatershed. Structure Estimated Cost Notes Twin Lakes Park Pond Survey in 2008 Cedar Meadows Pond Survey in 2008 Dependant on Lake Calhoun Ponds outcome of survey Survey in 2008 Lake Nokomis Ponds Surveyed in 2005; resurvey in 2008 Pamela Park Ponds Survey in 2008

5.8.9 Other Projects This Plan identified the need to consider additional projects not included in the prioritized 2007- 2017 CIP. These include regional infiltration opportunities in subwatershed units MC-140, 147, and 151 (see Section 5.8.5 above); four priority reaches of Minnehaha Creek as noted above; and dredging Longfellow Lagoon to remove accumulated fine sediments. The Board may consider such projects during the time frame of this Plan if funds are available.

Project Longfellow Lagoon Dredging Description Dredging fine sediment accumulated in the Longfellow Lagoon impoundment Need The Stream Assessment identified a sediment delta in Longfellow Lagoon. Fine sediments drop out and accumulate in this impoundment. To preserve channel conveyance and improve aesthetics, consideration should be given to dredging the lagoon. Outcome Improved aesthetics, habitat, and water quality Estimated Design, construction, project management. $114,100 Cost and Funding source for this project is the District Funding capital levy. Schedule One Year Prior to Construction: Design, cooperative agreement No Year Assigned: Construction of stream restoration

Project Reach 2 Restoration Description Streambank restoration, buffer reestablishment, enhancement of in-stream habitat features Need This reach extends from just above Minnehaha Falls to the Hiawatha

April 2007 Minnehaha Creek Subwatershed Page 94

Avenue weir. It contains a few streambank erosion sites and locations where retaining walls have failed. Fish spawning habitat is poor as fine sediment is deposited behind the weir in the Longfellow Lagoon. The riparian corridor is poor or nonexistent and in need of improvement. The reach scored a 4.3 on the Stream Visual Assessment Protocol index evaluated as part of the Minnehaha Creek Stream Assessment. The project would focus on improving the streambank stability and quality of the riparian area through bioengineering and native vegetation plantings as well as installation of in-stream habitat features. Outcome Stabilized streambanks with both hard armoring and bioengineering to reduce erosion; improved riparian zone with native vegetation; improved fish and macroinvertebrate habitat; improvement in SVAP index to a score greater than 5.0. Estimated Design, construction, project management, $190,200 Cost and vegetation management contract. Funding source Funding for this project is the District capital levy. Schedule One Year Prior to Construction: Design, cooperative agreement No Year Assigned: Construction of stream restoration

Project Reach 11 Restoration Description Streambank restoration, buffer reestablishment, enhancement of in-stream habitat features Need This reach extends from Lyndale Avenue to Logan Avenue S. It contains storm sewer outfalls that require repair or improvement, and unpaved trails on the right bank that may exacerbate erosion. The riparian corridor is a mix of turf grass maintained to an eroding creek edge and stable banks with riparian tree and shrub growth. The reach scored a 5.7 on the Stream Visual Assessment Protocol index evaluated as part of the Minnehaha Creek Stream Assessment, mainly due lack of in-stream fish and invertebrate habitat. The project would focus on improving the streambank stability and quality of the riparian area through bioengineering and native vegetation plantings as well as installation of in-stream habitat features. Outcome Stabilized streambanks with both hard armoring and bioengineering to reduce erosion; improved riparian zone with native vegetation; improved fish and macroinvertebrate habitat; improvement in SVAP index to a score greater than 6.0. Estimated Design, construction, project management, $1,179,500 Cost and vegetation management contract. Funding source Funding for this project is the District capital levy. Schedule One Year Prior to Construction: Design, cooperative agreement

April 2007 Minnehaha Creek Subwatershed Page 95

Project Reach 11 Restoration No Year Assigned: Construction of stream restoration

Project Reach 18 Restoration Description Streambank restoration, buffer reestablishment, enhancement of in-stream habitat features Need This reach extends from West 44th Street to Soo Line Railroad Bridge. The riparian corridor is a mix of turf grass maintained to an eroding creek edge and stable banks with riparian tree and shrub growth. Establishing native vegetation on streambanks and in buffers would help stabilize eroding streambanks. The reach scored a 6.2 on the Stream Visual Assessment Protocol index evaluated as part of the Minnehaha Creek Stream Assessment, mainly due to lack of in-stream fish and invertebrate habitat and poor riparian conditions. The project would evaluate the replacement of existing 44th Street bridge grade control riffle would restore the stream to a more free-flowing condition. Outcome Stabilized streambanks with both hard armoring and bioengineering to reduce erosion; improved riparian zone with native vegetation; improved fish and macroinvertebrate habitat; improvement in SVAP index to a score greater than 7.0. Estimated Design, construction, project management, $443,900 Cost and vegetation management contract. Funding source Funding for this project is the District capital levy. Schedule One Year Prior to Construction: Design, cooperative agreement No Year Assigned: Construction of stream restoration

Project Reach 29 Restoration Description Streambank restoration, buffer reestablishment, enhancement of in-stream habitat features Need This reach extends from Bridge Street to the I-494 west off ramp. The riparian corridor is a mix of turf grass maintained to an eroding creek edge and stable banks with riparian tree and shrub growth. Invasive species dominate the riparian zone. Invasive species should be eradicated and native riparian cover established or enhanced throughout the reach. The reach scored a 4.8 on the Stream Visual Assessment Protocol index evaluated as part of the Minnehaha Creek Stream Assessment, mainly due to lack of in-stream fish and invertebrate habitat. Meander reconstruction could improve stream complexity and improve in-stream habitat conditions.

April 2007 Minnehaha Creek Subwatershed Page 96 Outcome Stabilized streambanks with both hard armoring and bioengineering to reduce erosion; improved riparian zone with native vegetation; improved fish and macroinvertebrate habitat; improvement in SVAP index to a score greater than 6.0. Estimated Design, construction, project management, $862,400 Cost and vegetation management contract. Funding source Funding for this project is the District capital levy. Schedule One Year Prior to Construction: Design, cooperative agreement No Year Assigned: Construction of stream restoration

5.8.10 Taft-Legion Lake Regional Volume and Load Reduction Project Taft-Legion Lake Regional Volume and Load Reduction Description The City of Richfield proposed the collaborative implementation of an improvement project that, when completed, will provide treatment for urban stormwater runoff discharging into Taft Lake and Legion Lake, subsequently improving the quality of water discharged from the City of Richfield’s boundaries to Lake Nokomis and ultimately Minnehaha Creek.

Project plans include several different elements working in combination to achieve water-quality and volume-management improvements. Elements under consideration include:

Irrigation: Stormwater runoff will be withdrawn from stormwater basins and applied via irrigation to adjacent park land at Legion and/or Taft Lakes.

Infiltration: The infiltration system will operate concurrent with the proposed irrigation system. Depending on seasonal rainfall variation, if additional water is available to be withdrawn from the enhanced basins/ponds, water will be directed to underground infiltration systems in park land surrounding Taft Lake and Legion Lake.

Flocculation Enhanced Stormwater Pond: An existing road around the north end of Taft Lake will be removed to facilitate the construction of a stormwater pond with a flocculation system that will remove dissolved pollutants from storm sewer runoff that’s delivered to the system.

Flocculation of Water from Taft Lake: In addition to treating runoff delivered to a constructed stormwater pond on the north side of Taft Lake the flocculation system will have the capacity to treat water withdrawn from adjacent stormwater ponds and/or the hypolimnion of Taft Lake, removing dissolved pollutant loads, before it’s discharged back into Taft Lake.

Amendment Effective Date: Minnehaha Creek Subwatershed Page 97-a July 26, 2012

Natively Planted Lakeshore Buffers: Native lakeshore buffers will be established in select areas surrounding Legion Lake.

Pre-Treatment of Runoff to Legion Lake: A series of sedimentation ponds and/or enhanced grit-removal chambers will be installed to remove sediment and phosphorus loads prior to being discharged into Legion Lake.

Stakeholder engagement and educational efforts: Efforts to develop a comprehensive outreach, education and stakeholder engagement plan will be integrated into the design of each element of the project, and communications tools will be used to support citizens’ understanding of the purpose and function of the project.

Need Implementation of this project will address several goals of the 2007 MCWD Comprehensive Water Resource Management Plan and enable the City of Richfield to meet its various obligations to reduce annual stormwater volumes and pollutant loads.

MCWD goals addressed include:

MCWD Goal 1: Abstraction/Filtration. Promote abstraction and filtration of surface water where feasible for the purposes of improving water quality and increasing groundwater recharge throughout the watershed.

MCWD Goal 2: Ecological Integrity. Promote activities that maintain, support and enhance floral, faunal quantity and ecological integrity of upland and aquatic resources throughout the watershed.

MCWD Goal 3. Water Quality. Preserve, maintain and improve aesthetic, physical, chemical and biological composition of surface waters and groundwater within the District

MCWD Goal 5. Water Quantity. Maintain or reduce existing flows from drainage within the watershed to decrease the negative effects of stormwater runoff and bounce from existing and proposed development as well as provide low flow augmentation to surface waters.

MCWD Goal 6. Shorelines and Streambanks. Preserve the natural appearance of shoreline areas.

MCWD Goal 9. Education and Communications. Enhance public participation and knowledge regarding District activities and provide informational and educational material to municipalities, community groups, businesses, schools, developers, contractors and individuals.

Amendment Effective Date: Minnehaha Creek Subwatershed Page 97-b July 26, 2012 Implementation of the various project elements also is expected to address the impairment of Lake Nokomis by excessive nutrients, as described in the Total Maximum Daily Load study for the lake. The study determined that annual phosphorus loading to the lake from stormwater runoff generated by the City of Richfield and the Metropolitan Airports Commission must be reduced by 16 pounds.

Outcome This project is designed and intended to provide both volume and phosphorus load reductions as shown in the table below:

Project Element Water Volume P Load Reduction (ac-ft/yr) Reduction (lbs/yr) Water Reuse Irrigation System (Legion Lake) 10-40 12-50 Stormwater Infiltration (Legion/Taft Lake) and Ponding (Taft) 120-240 125-240 Mechanical Grit Chambers (Legion) - 0-24 Native Lakeshore Buffer (Legion) minor 2-8 Flocculation System (Taft) - 40-160

Project Element Estimated Capital Cost

Water Reuse Irrigation System (Legion Lake) $ 300,000

Stormwater Reuse Infiltration (Legion/Taft Lake) and Ponding

(Taft) $ 1,140,000

Proprietary Grit Chambers

(Legion) $ 300,000

Native Lakeshore Buffer (Legion) $ 60,000

Flocculation System (Taft) $ 900,000

TOTAL CAPITAL COST $ 2,700,000

Annual Operation, Maintenance

and Monitoring $ 150,000

TOTAL O&M Cost (20 year life) $ 3,000,000

To avoid or minimize a levy increase, if the project is ordered, consideration will be given to funding the $2,700,000 necessary for construction through a combination of upfront city financing of capital costs and a reduced, recurring annual District ad valorem levy over 20 years. Other alternative frameworks and sources of funding, such as grants, also will be considered.

Amendment Effective Date: Minnehaha Creek Subwatershed Page 97-c July 26, 2012 Estimated $2,700,000

Cost Schedule Implementation between 2012 - 2013

5.9 Summary

The following tables summarize the proposed implementation action items and their relationship to overall District the problems and issues identified in Section 3.0 above, the metrics by which the District will be evaluating progress toward resolving those issues and problems, the estimated District cost of implementing these actions, and anticipated implementation schedule.

Amendment Effective Date: Minnehaha Creek Subwatershed Page 97-d July 26, 2012

April 2007

Table 25. Problems and issues identified in the Minnehaha Creek subwatershed and actions proposed to address them. Problem or Issue Actions in Implementation Plan Degree of Improvement The water quality in Minnehaha Creek as • A series of stream restoration projects to stabilize Implementation of actions in this Plan measured by total phosphorus and TSS streambanks to reduce pollutant loading from bank would maintain or improve water quality concentrations is comparable to the MPCA’s erosion, improve buffers, and increase habitat and ecologic integrity in Minnehaha Creek ecoregion guidelines. Phosphorus and sediment • Actions to increase infiltration in the subwatershed to loads in Minnehaha Creek increase upstream to reduce pollutant loading conveyed from stormwater

Water Quality downstream, although the impoundments at the runoff major grade controls act as settling basins and • Continued monitoring of Minnehaha Creek for trap some of the pollutants and sediment. various parameters including bacteria Average chloride concentrations are generally

Minnehaha Creek Subwatershed • A diagnostic study of Minnehaha Creek to evaluate lower than state standards, and dissolved oxygen potential to improve water quality and ecologic concentrations are generally sustained at levels integrity through in-stream and near-stream sufficient to maintain aquatic life. Monitoring restorations for e. coli bacteria shows increasing concentrations from upstream to downstream at levels sometimes exceeding state standards. Six lakes in the subwatershed have been • The draft TMDLs identify potential improvement Implementation of all the actions in the designated Impaired Waters on the state’s 303(d) projects that have been incorporated into this Plan. phosphorus load reduction plans for the list due to an excess of nutrients. The District • Continue monitoring the lakes to assess progress. lakes would theoretically reduce in-lake P has petitioned to remove two of those lakes. The concentrations, improve water clarity, and District is preparing Total Maximum Daily Load meet District goals and state and federal (TMDL) studies, including plans to reduce water quality standards. phosphorus loads into the lakes, for Nokomis, Diamond, Hiawatha, and Powderhorn Lakes. Page 98

April 2007 Problem or Issue Actions in Implementation Plan Degree of Improvement The HHPLS established and the Lake Hiawatha • Rules will be amended to require more stringent • Implementation of actions in this Plan TMDL assumes an in-creek total phosphorus pollutant load reduction on new development and would maintain or improve water concentration goal of 80 ug/L. The HHPLS redevelopment, including adding an abstraction quality and ecologic integrity in estimated that achieving this goal would require a requirement to reduce pollutant loading from runoff. Minnehaha Creek and theoretically 15 percent reduction in phosphorus loading to the • Cooperatively construct regional infiltration reduce pollutant loading conveyed to creek from the entire subwatershed, excluding improvements to mitigate impact of new runoff from Lake Hiawatha from the creek, the Chain of Lakes and Lake Nokomis lakesheds. development and to reduce pollutant loading from improving its water quality. However, not enough is known about in-stream existing development. • Would depend on ability of developers processes and sources to partition that load • A diagnostic study of Minnehaha Creek to evaluate to incorporate adequate BMPs on their reduction between loading from runoff and potential to improve water quality and ecologic projects and properly maintain them to loading from in-stream sources such as integrity through in-stream and near-stream sustain removal efficiencies. streambank erosion, internal loading, riparian

Minnehaha Creek Subwatershed restorations. • Depends on ability to develop wetlands, etc. cooperative or collaborative improvements. Development in the subwatershed has resulted in Rules will be amended to require more stringent pollutant • Implementation of actions in this Plan increased stormwater volumes conveying load reduction on new development and redevelopment, would maintain or improve water nutrients and sediment to the lakes and to including adding an abstraction requirement to reduce quality and ecologic integrity in Minnehaha Creek. Significant efforts and pollutant loading from runoff. Minnehaha Creek and the lakes that investments by the District and the local currently meet or exceed their water governments have been made to improve water quality goals. quality in the lakes through improvement • Would depend on ability of developers projects, restorations, and nonstructural BMPs to incorporate adequate BMPs on their such as education and street sweeping. As a projects and properly maintain them to result Brownie Lake, Cedar Lake, Lake of the sustain removal efficiencies. Isles, and Lake Calhoun meet or exceed their • Depends on ability to develop water quality goals. cooperative or collaborative improvements. Development, redevelopment, and reconstruction • Rules will be amended to require more stringent • Would depend on ability of developers in the subwatershed may provide opportunities to pollutant load reduction on new development and to incorporate adequate BMPs on their obtain a net decrease in volume of stormwater redevelopment, including adding a volume projects and properly maintain them to runoff, nutrient, and TSS loads. management requirement. sustain removal efficiencies. • Cooperatively construct regional infiltration • Depends on ability to develop improvements to mitigate impact of new runoff from cooperative or collaborative development. improvements. Page 99

April 2007 Problem or Issue Actions in Implementation Plan Degree of Improvement Drainage is conveyed through the subwatershed • A series of stream restoration projects to stabilize Completion of projects would repair through a network of storm sewers, ditches, streambanks to reduce pollutant loading from bank existing erosion and stabilize the creek wetlands and lakes that discharge to Minnehaha erosion, improve buffers, and increase habitat. where it is most at risk for future erosion. Creek. The Minnehaha Creek Stream • A program to collaboratively construct spot repairs Assessment identified 35 locations on the creek on reaches where full-scale restoration is not planned with significant erosion or bank failure, and at this time. Water Quantity Quantity Water numerous locations with less severe erosion. Channel bank stability is stressed by “flashy” storm discharges which produce high velocities and rapid increases and decreases in stage coupled with poor riparian zone management and numerous storm sewer outfalls. Minnehaha Creek Subwatershed Development of the subwatershed has resulted in • Rules will be amended to require more stringent • Would depend on ability of developers increased stormwater volumes and flow peaks pollutant load reduction on new development and to incorporate adequate BMPs on their and reduced infiltration and base flow in redevelopment, including adding a volume projects and properly maintain them to Minnehaha Creek. Development, management requirement. sustain removal efficiencies. redevelopment, and reconstruction in the subwatershed may provide opportunities to • Cooperatively construct regional infiltration • Depends on ability to develop achieve a net decrease in volume of stormwater improvements to mitigate impact of new runoff from cooperative or collaborative runoff, nutrient and TSS loads conveyed to those development. improvements. water resources. Limitations on discharges from the Grays Bay • A stream diagnostic and biotic integrity TMDL to Completion of projects would repair dam, reduced infiltration and baseflow, multiple identify stressors and the most effective ways to existing erosion and stabilize the creek impoundments on the creek, and channel reduce and mitigate for them where it is most at risk for future erosion, overwidening to accommodate high flows leads • A series of stream restoration projects to stabilize and improve habitat to reduce low-flow to extended periods when the flows and depths in streambanks to reduce pollutant loading from bank stress on aquatic life. the creek channel are insufficient for recreation erosion, improve buffers, and increase habitat. and severely stress aquatic life. • A program to collaboratively construct spot repairs on reaches where full-scale restoration is not planned at this time.

Page 100

April 2007 Problem or Issue Actions in Implementation Plan Degree of Improvement Several landlocked subwatershed units and Cities are prohibited from adding outlets to landlocked Completed as LGUs complete their local individual subbasins are present in the basins, and must provide for adequate storage and volume plans. subwatershed, primarily in Minnetonka and St. control. Louis Park. As identified in the HHPLS, several of these subwatersheds or basins are being considered by the cities for outletting, altering local hydrology and potentially creating downstream volume or water quality impacts. Within these landlocked basins, any future development or redevelopment should minimize creation of new stormwater volumes. Impoundments and grade control structures along A diagnostic study of Minnehaha Creek to evaluate Implementation of actions in this Plan Minnehaha Creek Subwatershed the creek cause sediment to be deposited and potential to improve water quality and ecologic integrity would maintain or improve water quality accumulate, limiting habitat values. through in-stream and near-stream restorations. and ecologic integrity in Minnehaha Creek The HHPLS identified multiple locations within LGUs directed to evaluate these locations as part of their Completed as LGUs complete their local the subwatershed that are predicted to overtop local water management planning. plans. during the 100 year event, including city streets, trails, and driveways. The HHPLS identified several locations where LGUs directed to evaluate these locations as part of their Completed as LGUs complete their local for both existing and future conditions, higher local water management planning. plans. velocities than desired may result in erosion at outlets or culverts. The subwatershed includes several wetlands with • Key Conservation Areas identified that include high- • Ongoing effort that is dependant on high to exceptional vegetative diversity, fish and value wetlands. Some of these areas are identified as property owner willingness to pursue wildlife habitat and aesthetic values that need to District priorities for continued implementation of the conservation, District budget and staff be protected. Wetlands Land Conservation Program, and thus the District capacity, and LGU plan completion. would proactively look for opportunities to conserve these resources. The Capital Improvement Program includes funds for Land Conservation Activities. In all key areas, LGUs are required to include in their local plans strategies for conserving these values. • Rules will be amended to establish management • Implementation of revised rules would standards based on management classification for help minimize future impacts to the impacts to wetlands from development and highest-value wetlands while still redevelopment. providing a measure of protection to those that provide mainly downstream Page 101 resource protection.

April 2007 Problem or Issue Actions in Implementation Plan Degree of Improvement Most of the wetlands in the subwatershed have • Wetland restorations will be evaluated as part of the An initial effort that identifies for been impacted by development, as indicated by creek diagnostic restoration those wetlands that would result the lack of wetlands with exceptional to high • Wetlands identified as being of high to moderate in improvement to water quality in the vegetative diversity given the size of the wetland potential would be managed according to a lakes. This would begin to mitigate subwatershed. Degraded wetlands with high to Manage 1 wetland classification if they have been wetland losses from past development and moderate restoration potential should be assessed as a Manage 2 or 3. This would minimize help to increase the quantity and quality of considered for protection and restoration. further degradation that might make future restoration wetlands present. more difficult or costly. Most of the subwatershed is fully developed at Key Conservation Areas identified that include high-value Ongoing effort that is dependant on urban and suburban densities, with opportunities wetlands. Some of these areas are identified as District property owner willingness to pursue for the conservation of ecological integrity being priorities for continued implementation of the Land conservation, District budget and staff primarily within the creek corridor or some larger Conservation Program, and thus the District would capacity, and LGU plan completion. Minnehaha Creek Subwatershed wetland complexes. proactively look for opportunities to conserve these resources. The Capital Improvement Program includes funds for Land Conservation Activities. In all key areas,

Ecological Integrity Integrity Ecological LGUs are required to include in their local plans strategies for conserving these values. Fish surveys have been completed by the DNR • Continue to work cooperatively with the DNR, Depends on response of natural community on the major lakes in the subwatershed, and the MPRB, and Three Rivers on fisheries issues. to habitat improvement. fisheries are actively managed through stocking. • Support the fisheries through the improvement of water quality. A fish survey conducted by the DNR on • Support the DNR in its management efforts. Depends on the extent of infestation. If Minnehaha Creek found mostly lake species with • Evaluate milfoil management as part of internal load control of milfoil and other invasive aquatic few adults, indicating a lack of suitable habitat management diagnostic and feasibility study. vegetation will help achieve internal and few refuges for overwintering and low flow • A stream diagnostic and biotic integrity TMDL to phosphorus load reduction goals, then a periods. identify stressors and the most effective ways to significant improvement can be had reduce and mitigate for them through chemical or other control. If control would not benefit lake water quality, then there would be no improvement. Macroinvertebrate communities in Minnehaha • A stream diagnostic and biotic integrity TMDL to Depends on response of natural community Creek are limited by frequent wetland and identify stressors and the most effective ways to to habitat improvement. impounded reaches, water quality, and lack of reduce and mitigate for them. habitat. • A series of stream restoration projects to stabilize streambanks to reduce pollutant loading from bank erosion, improve buffers, and increase habitat. Page 102

April 2007 Problem or Issue Actions in Implementation Plan Degree of Improvement Eurasian watermilfoil is present in many of the • Support the DNR and MPRB in their management Depends on the extent of infestation. If lakes, and the Minneapolis Park Board performs efforts. control of milfoil and other invasive aquatic weed cutting on the Chain of Lakes to better • Evaluate milfoil management as part of internal load vegetation will help achieve internal support swimming and boating. management diagnostic and feasibility study. phosphorus load reduction goals, then a significant improvement can be had through chemical or other control. If control would not benefit lake water quality, then there would be no improvement. Development of the subwatershed has resulted in • Amend rules to require infiltration or abstraction of • Infiltration on site will assist in increased stormwater volumes and flow peaks the first one inch of rainfall on new permitted preventing further modification of and reduced infiltration and base flow in development and redevelopment. surficial groundwater recharge and Minnehaha Creek Subwatershed Minnehaha Creek. Development, help to maintain wetland hydrologic redevelopment, and reconstruction in the regimes. Groundwater Groundwater subwatershed may provide opportunities to • Identify a network of surficial aquifer monitoring • Implementation of monitoring network decrease stormwater runoff volumes and increase wells across the watershed, monitor groundwater will fill data gap and allow for infiltration levels and quality. identification of trends. • Identify baseflow in Minnehaha Creek and monitor • Identification of baseflow will fill data for trends. gap, allow for identification of trends, and improve understanding of hydrology and hydraulics of Minnehaha Creek. Ongoing flow monitoring in Minnehaha Creek • Amend rules to require infiltration or abstraction of Depends on outcome of study and suggests that some reaches of the creek are losing the first one inch of rainfall on new permitted recommendations flow to groundwater, possibly contributing to development and redevelopment. periods of low or intermittent flow. • A stream diagnostic and biotic integrity TMDL to identify stressors and the most effective ways to reduce and mitigate for them Seeps and springs are present in the • Amend rules to require pretreatment of stormwater Will help minimize future impacts to subwatershed, mainly in the limestone cliffs of discharged to wetlands or infiltration areas in the groundwater and provide for proactive the Gorge. The most prominent spring is Camp areas of high aquifer sensitivity. management rather than reactive Coldwater Spring. Hydrologic analysis and • Establish a new District rule that requires an monitoring conducted at the time the Minnesota additional level of analysis and review of permitted Department of Transportation proposed to development and redevelopment where there is a construct a new highway interchange nearby potential for development to adversely impact indicate this historic spring is sensitive to impacts Page 103 groundwater connected to a surface water feature. in its groundwatershed

April 2007 Problem or Issue Actions in Implementation Plan Degree of Improvement The extensive wetlands in the upper • Amend rules to require infiltration or abstraction of Infiltration on site will assist in preventing subwatershed were identified in the FAW as the first one inch of rainfall on new permitted further modification of surficial either discharge wetlands or combination development and redevelopment. groundwater recharge and help to maintain recharge-discharge wetlands. It will be critical to • Identify a network of surficial aquifer monitoring wetland hydrologic regimes. maintain or increase infiltration rates in the upper wells across the watershed, monitor groundwater subwatershed to help maintain hydrology to these levels and quality. wetlands. Wetlands in the lower subwatershed • Promote Better Site Design (Low Impact are mainly recharge or combination wetlands. Development) principles for new development that The hydrology of these wetlands depends on mimic predevelopment hydrologic regime. maintaining local flow patterns and rates Much of the subwatershed is very highly or • Amend rules to require pretreatment of stormwater Will help minimize future impacts to

Minnehaha Creek Subwatershed highly sensitive to aquifer impacts, including the discharged to wetlands or infiltration areas in the groundwater and provide for proactive Minnehaha Creek corridor areas of high aquifer sensitivity. management rather than reactive • Establish a new District rule that requires an additional level of analysis and review of permitted development and redevelopment where there is a potential for development to adversely impact groundwater connected to a surface water feature. Wellhead Protection Areas have been identified • Stormwater and groundwater management within • Will help minimize future impacts to for the cities of Edina, Minnetonka and St. Louis those areas will be coordinated with wellhead drinking water and provide for Park within this subwatershed. Stormwater protection plans. proactive management rather than management within those areas should be reactive coordinated with wellhead protection plans Page 104

Table 26. Summary of metrics to be used in evaluating progress toward Minnehaha Creek subwatershed goals. Objective Metric Existing Desired Location Phosphorus Loading 665 562 Lake Harriet (lbs annually) (Ultimate) Phosphorus Loading 908 599 Lake Nokomis (lbs annually) (Ultimate) Water Phosphorus Loading 11,126 10,038 Lake Hiawatha Quality (lbs annually) (Ultimate) Phosphorus Loading 486 265 Diamond Lake (lbs annually) (Ultimate) Phosphorus Loading 267 90 Powderhorn Lake (lbs annually) (Ultimate) Volume Reduction 1,298 Watershed-wide (Acre-feet) Water 1.5 year discharge 219.7 219.7 Watershed-wide Quantity (cfs) 100 year discharge 676.2 676.2 Watershed-wide (cfs) Ecologic Index of Biotic 3.51 Above MPCA Integrity Integrity (F-IBI) impairment threshold Minnehaha Creek Reach 30 Above MPCA N/A impairment threshold Minnehaha Creek Reach 29 Above MPCA N/A impairment threshold Minnehaha Creek Reach 28 Above MPCA N/A impairment threshold Minnehaha Creek Reach 27 3.76 Above MPCA (F-IBI) impairment threshold Minnehaha Creek Reach 26 Above MPCA N/A impairment threshold Minnehaha Creek Reach 25 Above MPCA N/A impairment threshold Minnehaha Creek Reach 24 Above MPCA N/A impairment threshold Minnehaha Creek Reach 23 N/A Above MPCA impairment threshold Minnehaha Creek Reach 22 4.78 Above MPCA (F-IBI) impairment threshold Minnehaha Creek Reach 21 5.39 Above MPCA (F-IBI) impairment threshold Minnehaha Creek Reach 20 Above MPCA N/A impairment threshold Minnehaha Creek Reach 19 Above MPCA N/A impairment threshold Minnehaha Creek Reach 18 Above MPCA N/A impairment threshold Minnehaha Creek Reach 17 4.88 Above MPCA (F-IBI) impairment threshold Minnehaha Creek Reach 16 Above MPCA N/A impairment threshold Minnehaha Creek Reach 15 Above MPCA 5.56 impairment threshold Minnehaha Creek Reach 14

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Objective Metric Existing Desired Location (F-IBI) 4.00 Above MPCA (F-IBI) impairment threshold Minnehaha Creek Reach 13 5.31 Above MPCA (F-IBI) impairment threshold Minnehaha Creek Reach 12 5.13 Above MPCA (F-IBI) impairment threshold Minnehaha Creek Reach 11 3.96 Above MPCA (F-IBI) impairment threshold Minnehaha Creek Reach 10 5.08 Above MPCA (F-IBI) impairment threshold Minnehaha Creek Reach 9 4.24 Above MPCA (F-IBI) impairment threshold Minnehaha Creek Reach 8 Above MPCA N/A impairment threshold Minnehaha Creek Reach 7 Above MPCA N/A impairment threshold Minnehaha Creek Reach 6 Above MPCA N/A impairment threshold Minnehaha Creek Reach 5 Above MPCA N/A impairment threshold Minnehaha Creek Reach 4 Above MPCA N/A impairment threshold Minnehaha Creek Reach 3 Above MPCA N/A impairment threshold Minnehaha Creek Reach 2 4.26 Above MPCA (F-IBI) impairment threshold Minnehaha Creek Reach 1 Stream Visual 6.3 5.0 or 1+ existing Minnehaha Creek Reach 30 Assessment Protocol 4.8 5.0 or 1+ existing Minnehaha Creek Reach 29 7.0 5.0 or 1+ existing Minnehaha Creek Reach 28 7.5 5.0 or 1+ existing Minnehaha Creek Reach 27 6.3 5.0 or 1+ existing Minnehaha Creek Reach 26 6.4 5.0 or 1+ existing Minnehaha Creek Reach 25 2.0 5.0 or 1+ existing Minnehaha Creek Reach 24 4.1 5.0 or 1+ existing Minnehaha Creek Reach 23 6.1 5.0 or 1+ existing Minnehaha Creek Reach 22 7.0 5.0 or 1+ existing Minnehaha Creek Reach 21 2.0 5.0 or 1+ existing Minnehaha Creek Reach 20 6.1 5.0 or 1+ existing Minnehaha Creek Reach 19 6.0 5.0 or 1+ existing Minnehaha Creek Reach 18 2.0 5.0 or 1+ existing Minnehaha Creek Reach 17 5.8 5.0 or 1+ existing Minnehaha Creek Reach 16 5.8 5.0 or 1+ existing Minnehaha Creek Reach 15 5.6 5.0 or 1+ existing Minnehaha Creek Reach 14 7.1 5.0 or 1+ existing Minnehaha Creek Reach 13 3.8 5.0 or 1+ existing Minnehaha Creek Reach 12 5.7 5.0 or 1+ existing Minnehaha Creek Reach 11 6.9 5.0 or 1+ existing Minnehaha Creek Reach 10 5.1 5.0 or 1+ existing Minnehaha Creek Reach 9

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Objective Metric Existing Desired Location 5.1 5.0 or 1+ existing Minnehaha Creek Reach 8 4.0 5.0 or 1+ existing Minnehaha Creek Reach 7 2.0 5.0 or 1+ existing Minnehaha Creek Reach 6 3.0 5.0 or 1+ existing Minnehaha Creek Reach 5 4.7 5.0 or 1+ existing Minnehaha Creek Reach 4 2.0 5.0 or 1+ existing Minnehaha Creek Reach 3

4.3 5.0 or 1+ existing Minnehaha Creek Reach 2 7.6 5.0 or 1+ existing Minnehaha Creek Reach 1 Key Conservation Areas conserved 98 Watershed-wide (acres) 3,874.0 3,874.0 or greater Watershed-wide 1,035.3 1,035.3 or greater Preserve Wetlands Wetland Acreage 575.6 575.6 or greater Manage 1 314.7 314.7 or greater Manage 2 735.5 735.5 or greater Manage 3

Table 27. Summary of Minnehaha Creek subwatershed implementation program. Item Description Estimated Cost Schedule Section 3.0 MCWD Capital Projects 1 Stream restorations $944,100 2014 3.1.1, 3.1.3, 3.2.1, $451,000 2015 3.2.2, 3.2.3,3.2.5, $654,800 2012 3.3.1, 3.4.3, 3.4.4 $967,600 2007 $877,700 2015 $1,380,100 2016 $896,000 2012 $1,203,400 2010 2 Minnehaha Falls Glen Restoration $1,795,300 2008 3 Lake Nokomis internal load $342,100 2007 3.2.5 management 4 Regional infiltration $410,100 2013 3.1.1, 3.1.2, 3.1.3, $485,400 2012 3.1.5, 3.2.2, 3.2.4, $3,533,000 2009 3.5.1, 3.5.2, 3.5.3, $2,440,600 2011 3.5.4 $2,299,800 2008 $2,221,500 2013 $1,051,900 2015 $915,400 2012 $435,200 2016 $1,504,500 2014 MCWD Data Acquisition/Study 1 Minnehaha Creek Subwatershed $200,000 2008 3.1.1, 3.1.2, 3.1.4, Volume and Load Reduction Study 3.2.1, 3.2.2, 3.2.7, 3.3.3, 3.4.3, 3.4.4, 3.5.1

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Item Description Estimated Cost Schedule Section 3.0 2 Develop infiltration/filtration Part of watershed- 2008 3.1.2, 3.1.4, 3.2.1, strategies appropriate to wellhead wide study 3.2.2, 3.2.3, 3.2.4, protection areas and areas of 3.2.6, 3.2.7, 3.3.1, groundwater sensitivity 3.3.3, 3.4.1, 3.5.1, 3.5.2, 3.5.3, 3.5.4 3 Identify key indicator species, Part of watershed- 2010 and ongoing 3.3.1, 3.3.2, 3.3.3, evaluate habitat, and develop wide study 3.4.1, 3.4.3, 3.4.4 conservation strategies MCWD Land Conservation Program 1 Undertake land conservation efforts $4,215,000 Part of ongoing 3.1.2, 3.1.4, 3.2.2, in accordance with Figure 19 watershed-wide 3.3.1, 3.3.2, 3.3.3, program 3.4.1, 3.4.3, 3.4.4, 3.5.1 MCWD Regulatory Program 1 Amend District Rules to increase Part of watershed- 2007-2009 3.1.1 - 3.1.4, 3.4.4 stormwater management wide effort requirements for new development and redevelopment 2 Amend District Rules to require Part of watershed- 2007-2009 3.1.1 - 3.1.4, 3.2.1, abstraction of 1” of rainfall on wide effort 3.2.2, 3.2.4, 3.2.5, permitted development and 3.2.6, 3.2.7, 3.5.4, redevelopment 3 Amend District Rules to adopt Part of watershed- 2007-2009 3.3.1, 3.3.2, 3.3.3, wetland management rules based on wide effort 3.4.1, 3.5.1, 3.5.4 wetland management classification MCWD Hydrodata Program 1 Monitor Minnehaha Creek Part of watershed- Part of ongoing 3.1.1, 3.1.2, 3.1.3, wide hydrologic data watershed-wide 3.1.4, 3.2.2, 3.2.3, program program 3.2.4, 3.5.1, 3.5.2 2 Monitor macroinvertebrates in Part of watershed- 2008, 2012 3.4.1, 3.4.3, 3.4.4 Minnehaha Creek every five years wide hydrologic data program 3 Identify base level flow in Part of watershed- Part of ongoing 3.2.2, 3.2.3, 3.4.3, Minnehaha Creek wide study watershed-wide 3.4.4, 3.5.1, 3.5.2 program 4 Identify shallow wells to monitor Part of watershed- 2008 3.2.2, 3.2.3, 3.3.3, groundwater levels wide study 3.3.2, 3.5.1, 3.5.2, 3.5.3, 3.5.4 MCWD Education/Communication Program 1 Provide targeted education materials Part of watershed- Part of ongoing All to key stakeholder groups to meet wide education watershed-wide objectives of plan program program 2 Provide workshops, seminars, and Part of watershed- Part of ongoing 3.1.1- 3.1.4, 3.2.1, brown bags for LGU staff, wide education watershed-wide 3.2.2, 3.2.4, 3.2.6, developers, and other interested program program 3.2.7, 3.3.1, 3.3.2, parties 3.3.3, 3.4.1, 3.5.1 - 3.5.4 3 Develop and distribute model Part of watershed- Part of ongoing 3.1.2-3.1.4, 3.2.2, ordinances and design standards that wide education watershed-wide 3.2.4, 3.3.1, 3.4.1, incorporate low impact design program program 3.5.1, 3.5.2, 3.5.4 principles

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Item Description Estimated Cost Schedule Section 3.0 4 Develop a small grant program to Part of watershed- 2008 and ongoing 3.1.2, 3.1.3, 3.1.4, provide financial assistance to wide program 3.2.1, 3.2.2, 3.2.4, property owners desiring to 3.3.1, 3.3.2, 3.3.3, implement BMPs on their property 3.4.1, 3.4.3, 3.4.4, 3.5.1, 3.5.4 MCWD Operations and Maintenance 1 Inspect Minnehaha Creek erosion- Part of watershed- Part of ongoing 3.1.1, 3.1.4, 3.2.1, prone areas at least annually wide program watershed-wide 3.2.2, 3.2.7, 3.4.4 program 2 Monitor high vegetative-diversity Part of watershed- Part of ongoing 3.3.1 wetlands for exotic species wide program watershed-wide program 3 Inspect detention ponds to sustain Incorporate into life- Part of ongoing 3.1.1, 3.1.2, 3.1.3 removal efficiency cycle cost of project watershed-wide program Collaborative Projects 1 Work in partnership with MPRB to Ongoing activity Part of ongoing 3.1.2, 3.4.2, 3.4.3, develop and implement lake aquatic watershed-wide 3.4.5 management plans program 2 Work in partnership with Creek Ongoing activity Part of ongoing 3.1.1, 3.1.2, 3.1.4, riparian communities to improve watershed-wide 3.3.1, 3.3.2, 3.3.3, riparian zone vegetation program 3.4.1, 3.4.3, 3.4.4 management 3 Browndale Dam Scour Repair $50,500 2008 Same 4 Work in partnership with Creek $100,000 annually 2008 and ongoing Same riparian communities and other agencies and utilities to repair streambank erosion and stabilize outfalls and other infrastructure: establish annual fund 5 Work in partnership with MPRB to To be developed in As noted in the CIP 3.1.2, 3.1.3, 3.1.4, investigate and implement potential the Lake TMDL 3.2.2, 3.3.3, 3.4.1, capital improvements identified in Implementation Plan 3.4.2, 3.4.5 the lake TMDLs 6 Collaborate with the MPRB to To be developed in Part of ongoing 3.1.2, 3.4.2, 3.4.5 evaluate feasibility of internal load the Lake TMDL watershed-wide controls on Nokomis, Powderhorn, Implementation Plan program and Diamond Lakes

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April 2007 Minnehaha Creek Subwatershed Page 110