INDIAN CREEK WATERSHED PLAN EXECUTIVE SUMMARY

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1 INDIAN CREEK WATERSHED PLAN EXECUTIVE SUMMARY The Indian Creek Watershed covers a 38 square mile area in southern Lake County, Illinois that drains 24,116 acres before discharging into the Des Plaines River near Lincolnshire, Illinois. It is comprised of many streams, lakes, and land uses within 10 municipalities and unincorporated areas. The watershed includes four major stream branches (Indian Creek mainstem, Kildeer Creek, Diamond Lake Drain, and Seavey Ditch), and 650 acres of lakes. Historically, the Indian Creek Watershed supported a diverse fauna and flora including prairies, savannas, oak woodlands and wetlands. These natural communities served valuable functions including water quality benefits, wildlife habitat, soil stabilization, and retention and detention of stormwater. These functions became impaired as Europeans settled and altered the landscape by converting natural plant communities to agricultural land, channelizing streams and draining wetlands, and ultimately by constructing roads, houses and cities. Today, more than half (62%) of the watershed is developed in residential, commercial, industrial, institutional, and transportation land uses with only 38% remaining as open space. Predictably, flooding increased and water quality decreased as development pressure impaired the ability of the landscape to serve these functions. As a result, the Illinois EPA formally listed Indian Creek and two of its major lakes Big and Little Bear lakes on its 2002 Section 303(d) impaired waters list. The Indian Creek Watershed Committee (ICWC) was formed in 1999 to provide stakeholders in the watershed with an opportunity and forum to express their concerns, and to provide direction for watershed restoration through the Watershed Plan process. The Lake County Stormwater Management Commission (LCSMC) and the Watershed Project Team facilitated regular meetings during the 12-month watershed planning This natural river swale lies in an undeveloped area. It represents the historic structure of rivers in Illinois. process where the ICWC formalized a vision, goals and objectives for the watershed, and attended presentations educating participants on watershed issues. i

2 Goals and Objectives The vision of the ICWC is: To preserve, protect, restore and enhance the resources, function and values of the Indian Creek Watershed through stewardship, education and partnerships. Key goals and objectives identified during the watershed planning process are: Protect, Restore, Enhance, or Maintain Channel Function and Conveyance. Maintain or Improve Water Quality. Reduce Flooding. Maintain or Improve Biodiversity. Enrich Quality of Life and Develop Cultural Values for a Sustainable Watershed. Develop Environmentally Sustainable Recreation Opportunities. Demonstrate Economic Benefits and Provide Incentives for Sustainable Land Use Practices. Foster Watershed Stewardship and Awareness through Education. Utilize Open Space to Achieve Watershed-Wide Goals. Develop Stewardship Network for Long-Term Management and Monitoring. Develop or Enforce Regulations that Benefit Watershed-Wide Goals. Assessing the Watershed Condition The Project Team assessed the Indian Creek Watershed in a variety of ways to understand existing and projected future problems and opportunities. At the watershed scale, the Project Team assessed the topography, soils, wetlands, flooding and drainage, regional storage areas, streams and lakes, water quality, natural resources, land uses, development trends, and open space. The following summarizes some of the key results of the watershed scale assessment: Flood Damage Reduction One third (33.3%) of the watershed contains hydric soils. The remainder is moderately to well-drained soils with moderate runoff potential, infiltration and transmission rates. More than half of the pre-settlement wetlands in the watershed have been drained or filled. Of the remaining 2,957 acres of wetland, 15 wetlands consisting of 865 acres are classified as high quality wetlands per Lake County s Advance Identification (ADID) study. LCSMC s Flood Problem Areas Inventory of the watershed identified 15 flood problem areas (mostly failed local drainage). 3,243 structures were located within the Federal Emergency Management Association (FEMA) 100-year flood mapping area. ii

3 Forty-six (46) regionally significant storage areas were located and have the potential to store up to 384,582 acre-feet of stormwater runoff. Water Quality Improvement Percent impervious cover within the watershed is expected to increase from 28% to 36% over the next 20 years. Indian Creek, Little Bear Lake, and Big Bear Lake are included on the Illinois EPA 2002 Section 303(d) impaired waters list. Biological sampling conducted by the IEPA, IDNR and U.S. Army Corps of Engineers (USACE) indicates degraded water quality and habitat conditions in streams and lakes. Lake County Health Department-Lakes Management Unit studies indicate that most of the lakes in the watershed are in poor to average condition due to high nutrient levels (especially phosphorus), eroded banks, extensive development and the presence of invasive plant species. Natural Resource/Open Space Enhancement A LCSMC study found that most of the 51 reaches of inventoried streams were channelized, had eroded banks, heavy debris loads and exhibited poor riffle-pool complexes. Only two stream reaches contained a natural meandering channel. Several Illinois state-listed threatened and endangered species persist within the watershed, most of which are associated with wetlands and high-quality natural areas. Development covers 62% of the watershed. Residential (37%), agricultural (15%), and transportation (11%) are the largest categories of land use. An additional 3,734 acres of open land is expected to be developed over the next 20 years. The study identified 12,664 acres of open or partially open space in over 3,545 parcels within the project area. Another 17% (2,208 acres) of the watershed is protected open space. Assessing Subwatershed Conditions After assessing the watershed as a whole, the Project Team used topography to delineate 49 Subwatershed Management Units (SMUs) that ranged in size from 28 acres to 1,839 acres. Because SMUs are relatively small and have fewer political boundaries, they are more easily assessed, measured and analyzed. Watershed issues such as flood damage reduction, water quality improvement and natural resource protection become easily comparable allowing planners to rank SMUs based on immediate needs. iii

4 The Project Team assessed and compared each SMU based on runoff, stream flows, pollutant loading and vulnerability to development. Some of the key findings include: The hydrology models indicated that the major lakes had sufficient capacity to detain water during 2 and 10-year storm events; however, Bresen Lake, Kemper Lake, Lake Charles and Leo Lake would overtop during a 100-year event. Water level fluctuations caused by runoff in Sylvan Lake and Pond-A-Rudy are predicted to decrease with projected development due to more restrictive LCSMC detention requirements. Despite an expected increase in imperviousness, peak flows in all streams modeled, except for Seavey Ditch, are predicted to be lower than existing conditions with projected development due to more rigorous LCSMC detention requirements. Retrofitting detention basins constructed before 1992 so that they detain water per existing regulations could substantially reduce peak flows in all streams. Several SMUs in Indian Creek mainstem, Kildeer Creek branch, and Seavey Ditch had flows exceeding 4 feet per second (considered excessive) during existing and projected development conditions. Based on PondPack v7 hydrologic modeling software, 2-year storm flows should stay within the streambanks of all reaches. Reaches within eight SMUs at the downstream end of the watershed are projected to overtop their banks for the 10-year and 100-year storm events during existing and projected development. Five SMUs, generally in the upper reaches of the watershed, are predicted to flood only during a 100-year storm event. Using a pollutant loading analysis developed by LCSMC and the Northeastern Illinois Planning Commission (NIPC), 11 SMUs were identified as water quality hotspots. One SMU (#43) was identified as the worst water quality hotspot for existing and projected conditions. The Project Team modeled the potential effects various stormwater management strategies would have on water quality within a typical 40-acre development. A dry detention pond, a wet-bottomed pond and a Stormwater Treatment Train (STT; sediment basin-prairie filtration-wetland) were compared for single family, multifamily, and commercial land uses. Several pollutants were modeled for all three treatments and land uses. The dry detention pond removed only 26-67% of all pollutants; the wet pond removed 90-95% of all pollutants; and the STT removed 95-99% of all pollutants. The Project Team completed a vulnerability assessment of all 49 SMUs based on percent impervious cover and various field criteria. The 4-step assessment is designed to measure how sensitive specific SMUs are to development and associated imperviousness. According to the assessment, the eastern portion of the watershed is largely Non-Supporting (highly impervious and degraded) while the western portion is mostly Impacted (moderately impervious and somewhat degraded). Following 20-year projected land use conditions, the iv

5 entire watershed is expected to be mostly Non-Supporting, mostly due to an increase in imperviousness as the western portion of the watershed is developed. Toolbox of Watershed Best Management Practices (BMPs) The report includes a Toolbox of BMPs that provides specific types of in-the-ground projects and watershed policies that can be implemented to achieve watershed goals. The watershed restoration and management techniques described in the Toolbox, when applied to the Indian Creek Watershed, can help improve water quality, reduce flood damage, educate watershed residents, and protect, restore, and enhance natural resources and greenways. Parcel Prioritization As a first step toward targeting specific watershed improvement opportunities, the Project Team identified and weighted all open and partially open parcels within the watershed based on 15 criteria. Parcels were ranked independent of watershed goals, and then ranked under the categories of flood damage reduction, water quality improvement, and natural resources/greenways protection and enhancement. Parcels with the highest priority were ranked highest as an open space management priority. This parcel prioritization process was completed independently of the Prioritized Action Plan described later in the report, and it provides an additional and complementary tool for targeting specific open space for implementing BMPs. Prioritized Action Plan The Prioritized Action Plan provides stakeholders with action items for watershed-wide improvements. It serves to direct stakeholders toward specific sites for the implementation of BMPs and other action items. Some of these items could include: Acquire funding; Develop educational programs; Organize or participate in data collection; Provide regulatory or technical guidance; Issue permits; Acquire land for restoration or protection purposes; Oversee or implement restoration projects; and v

6 Monitor long-term success of watershed improvement projects. The Prioritized Action Plan is divided into a Programmatic Action Plan and a Site Specific Action Plan. The Programmatic Action Plan recommends action items with general applicability throughout the watershed. Action items are based on objectives developed by the Project Team and aim to reduce flood damage, improve water quality and protect natural resources/greenways. The Site Specific Action Plan identifies sites where flooding, water quality, or open space protection problems or opportunities have been identified. Only the highest priority sites were considered for inclusion in the plan. The list, which is organized by municipality, serves only as a starting point for watershed improvement projects and should be adjusted as projects are completed and additional sites are targeted. A priority ranking was assigned to site-specific action recommendations, but not to programmatic action recommendations. Assigning priority to watershed improvement projects is largely dependent on feasibility, which is determined by size of the project, location, land use, ownership, funding, scope of work and other factors. A feasibility study will be an important next step in the process of implementing many of the recommended actions. The following summarizes key recommendations listed by project goal found in the Site Specific Action Plan: Flood Damage Reduction Detention basins constructed before 1992 were identified and mapped in specific flood problem SMUs as retrofit opportunities to reduce flooding. The study identified, mapped, and recommended for additional assessment 14 of 46 potential depressional storage locations. Stream reaches exhibiting instream or overbank debris loads as well as sediment deposition were identified and mapped for stream maintenance activities. Open and partially open parcels adjacent to Flood Problem Areas (FPAs) were identified and mapped for potential flood reduction measures. High priority parcels in the 100-year floodplain were identified, mapped and included in the plan for potential flood damage reduction measures. Water Quality Improvement Streams and lakes with erosion problems were identified and mapped for enhancement or stabilization. High priority parcels with drained wetlands and located in the water quality hotspot SMUs were identified, mapped and targeted for wetland restoration. Problematic discharge pipes and hydraulic structures were identified, mapped and included in the plan for retrofits or repairs. Existing dry bottom, concrete lined and riprap lined detention basins were identified, mapped and included in the plan for water quality improvement retrofits. Stream reaches with inadequate buffers were identified, mapped and targeted for potential enhancement. Lakes with abundant invasive shoreline plant species were identified, mapped and recommended for invasive species removal. vi

7 Natural Resources/Greenways Protection and Enhancement High priority open and partially open parcels intersecting high quality natural resources were identified, mapped and assessed for potential acquisition. All open and partially open parcels intersecting proposed and unknown status trails/greenways were identified and mapped by municipality for potential acquisition and expansion opportunities. All additional high priority parcels for natural resource/greenways protection and enhancement were identified, mapped and included in the plan as high priority for protection. Stream reaches lacking adequate instream habitat were identified, mapped and targeted for habitat enhancement. Regulatory Changes The report proposes several regulatory changes to improve water quality, reduce flooding, improve habitat and provide other watershed benefits. Of particular significance to the Indian Creek Watershed may be a site-specific reduction in the required release rate of detention basins, especially near streams, to prevent erosion and downcutting following storm events. As an example, the required release rate for specific streams and drains in the Squaw Creek Mainstem system is 0.02 cubic feet per second (cfs) for the 2-yr storm compared to the WDO maximum allowable release rate of 0.04 cfs. Specific studies, such as the flood insurance study (FIS) flow rate analysis adopted by the LCSMC for the Squaw Creek Mainstem, could be adopted for Indian Creek Watershed SMUs to reduce in-stream erosion. Flooding upstream of detention basins is a potential risk associated with reducing the release rate of detention basins that already adhere to the WDO maximum allowable rate, and for this reason we encourage detailed site analysis and both upstream and downstream hydraulic and hydrologic modeling for specific sites that may benefit from an additional rate reduction. We expect that in most cases of severe streambank erosion, a release rate reduction for contributing detention basins would create more benefits for the receiving stream than flooding problems for upstream areas. Streambank erosion is a threat to water quality and flooding in the Indian Creek Watershed, particularly for sections of Indian Creek mainstem, Kildeer Creek, and the Seavey Ditch. These reaches have modeled velocities that exceed 4 feet/second under existing and post-developed conditions and modeled flows that exceed channel depths during the 10 and 100-year storm events. vii

8 The current maximum allowable release rates seem sufficient to control flooding and prevent bank erosion for all stream reaches for the 2-year storm event, even under post-developed conditions. However, flooding could be prevented and water quality could be improved in the watershed by reducing release rates for the 100-year storm event. The three project goals of reduced flooding, improved water quality, and open space/natural resource protection would be best achieved in the Indian Creek Watershed by requiring withinwatershed wetland mitigation. Efforts should be made at the regulatory level to preserve remaining wetlands in the watershed for the simple reason that they naturally function in flood control and water quality. A joint agreement between permitting agencies (LCSMC, USACE) and the U.S. Fish and Wildlife Service and the Natural Resources Conservation Service to mitigate for all wetland losses in the watershed should be pursued as the optimal action to achieve a no net loss policy at the watershed level. Funding Sources Opportunities to secure funds for restoration projects in the Indian Creek Watershed are widespread due to the scope of BMPs and diversity of actions available to meet the project goals of flood damage reduction, water quality improvement and open space protection. Public and private organizations that administer various conservation and environmental programs are often eager to form partnerships and leverage funds for land acquisition, restoration and environmental education. In this way, funds invested by partners in the Indian Creek Watershed can be doubled or tripled, although actual dollar amounts are difficult to measure. Funds generally fall into two relatively distinct categories (Conservation Fund et al., 2001). The first category is existing grant programs, funded by a public agency or by other sources. The second, one that can provide greater leverage, might be called money to be found. The key to this money is to recognize that any given project may have multiple benefits. A specific project to acquire and restore wetlands in the Indian Creek Watershed may be recognized by a partner organization as an opportunity to provide another benefit such as threatened and endangered species protection. It is important to note and explore all of the potential project benefits from the perspective of potential partners and to then engage those partners. Partners may wish to become involved because they believe the project will achieve their objectives, even if they have little interest in the specific objectives of the Indian Creek Watershed Plan. This report identifies potential partners and funds or cost-share opportunities grouped generally by project goal and organization. The programs identified are the most promising for projects likely to result from the watershed plan. It is anticipated that additional partnering and funding opportunities will be identified as the watershed plan is implemented. viii