Sligo Creek Subwatershed Action Plan

Table of Contents

Section 1: Vision and Existing Conditions 7 Need and Purpose 8 10-Year Vision 9 Sligo Creek 2020 Restoration Targets 10 Existing Conditions in the Sligo Creek Subwatershed 10 Problems Facing the Sligo Creek Subwatershed 16 Changes to Hydrology 16 Poor Aquatic Habitats 16 Poor Water Quality 16 Trash 20 Flooding 20 Existing Pollutant Loads 20

Section 2: Inventory of the Potential Restoration Projects 23 Inventory of the Potential Restoration Projects 24 Results of the Evaluation and Scoring of Restoration Actions in Sligo Creek Subwatershed 29 Stormwater Management 29 Stream Restoration 33 Wetland Creation and Restoration 34 Fish Blockage Removal or Modification 35 Riparian Reforestation, Meadow Creation, and Invasive Species Management 36 Trash Reduction 37 Parkland Acquisition 38 Summary of Recommended Restoration Actions 39 Implementation Type of Potential Restoration Actions 40

Section 3: Evaluation and Discussion of the Restoration Strategies 41 Evaluation of Proposed Restoration Strategies 42 Potential to Reduce Stormwater Pollutant Loads 42 Potential to Reduce Peak Flow Discharge 44 Potential to Reduce Pollutant Loads Using Street Sweeping 46 Pollutant Reduction of Homeowner Stormwater Management 49

Section 4: 10-Year Targets and Milestones 57 Sligo Creek 10-Year Targets and Milestones 58

List of Figures

Figure 1-1: Impervious Acres in Sligo Creek Subwatershed 12 Figure 1-2: Sligo Creek Subwatershed 13 Figure 1-3: Sligo Creek Subwatershed Planning Units 14 Figure 1-4: Sligo Creek Subwatershed BMP Location 15 Figure 1-5: NPDES Sites in Anacostia River Watershed 18 Figure 1-6: RCRA Sites in Anacostia River Watershed 19 Figure 3-1: Homeowner BMP Scenarios 51 Figure 3-2: Removal Efficiencies of Homeowner BMPs in WTM 52 Figure 3-3: Maximum Potential Pollutant Reduction versus Anacostia TMDL Goals 55

List of Tables

Table 1-1: Impervious Surfaces in the Sligo Creek Subwatershed and Existing Level of Control 12 Table 1-2: Nutrient Loading Estimates for Sligo Creek Subwatershed and Comparison Values 21 Table 1-3: TMDL Reduction Goals 21 Table 2-1: 2020 Sligo Creek Restoration Objectives 25 Table 2-2: Inventory of Restoration Projects in the Sligo Creek Subwatershed 26 Table 2-3: Proposed Restoration by Type in the Sligo Creek Subwatershed 27 Table 2-4: Provisional Restoration Project Estimated Unit Costs 28 Table 2-5: Top 20 Potential Stormwater Retrofit Projects within the Sligo Creek Subwatershed 30 Table 2-6: Top 5 Potential Stormwater Retrofit Projects within the Upper Sligo Creek Subwatershed 31 Table 2-7: Top 5 Potential Stormwater Retrofit Projects within the Middle Sligo Creek Subwatershed 31 Table 2-8: Top 5 Potential Stormwater Retrofit Projects within the Lower Sligo Creek Subwatershed 32 Table 2-9: Potential Stream Restoration Projects within the Sligo Creek Subwatershed 33 Table 2-10: Potential Wetland Creation or Restoration Projects within the Sligo Creek Subwatershed 34 Table 2-11: Potential Fish Blockage Removal or Modification Candidate Projects within the Sligo Creek Subwatershed 35 Table 2-12: Potential Riparian Reforestation, Meadow Creation, and Invasive Species Management Candidate Projects within the Sligo Creek Subwatershed 36 Table 2-13: Potential Trash Reduction Projects within the Sligo Creek Subwatershed 37 Table 2-14: Potential Parkland Acquisition Projects within the Sligo Creek Subwatershed 38 Table 2-15: Summary of Recommended Potential Restoration Actions 39 Table 2-16: Summary of Potential Restoration Actions Implementation Type 40 Table 3-1: Level of Stormwater Control in Sligo Creek Subwatershed After implementation of All Proposed Stormwater Projects 42 Table 3-2: Evaluation of Stormwater Control Levels and Potential in Pollutants Load Reduction 43 Table 3-3: Ability of Stormwater Control Levels to Address TMDL Goals in Sligo Creek Subwatershed 44 Table 3-4: Peak Flow Analysis Results for Sligo Creek Subwatershed 45 Table 3-5: Pollutant Reduction Estimate of Weekly Street Sweeping (Streets Only) 47 Table 3-6: Pollutant Reduction Estimate of Weekly Sweeping of Parking Lots 48 Table 3-7: Total Pollutant Reduction Estimate of Weekly Sweeping of All Streets and Parking Lots 48 Table 3-8: Sligo Creek Subwatershed Impervious Acres Analysis of Residential Homes 49 Table 3-9: Removal Efficiencies of Homeowner BMPs in WTM 52 Table 3-10: Pollutant Reduction of Homeowner Stormwater Control Scenarios 53 Table 3-11: Percent Reduction of Pollutants Estimated for Homeowner Scenarios and Acreage Controlled 53 Table 3-12: Maximum Potential Pollutant Reduction for Stormwater Controls, Homeowner BMPs, and Street Sweeping 55

Section 1 Vision and Existing Conditions

The Sligo Creek Subwatershed Action Plan (SWAP) is intended to be an integrated summary document for the Sligo Creek Subwatershed Environmental Baseline Conditions and Restoration Report and the Sligo Creek Subwatershed Provisional Restoration Project Inventory. Based on planning level analysis and evaluations, various activities or actions have been identified as part of a 10-year comprehensive restoration plan for the Anacostia River watershed. In addition, the layout of the report is intended to follow as closely as possible the EPA nine key elements to develop a watershed plan to improve water quality impairments, and are the minimal requirements to be eligible to receive incremental Clean Water Act Section 319 funding (EPA, 2008).

Need and Purpose

The Anacostia River watershed is primarily confined to an urban landscape, characterized by an alteration of the natural landscape features to accommodate the population growth and urban sprawl that has occurred over the decades. The increase in impervious areas disrupted the natural hydrologic cycle and ultimately affected the environmental health of the Anacostia River and its tributaries. Urbanization throughout the years caused excessive runoff and a reduction in groundwater recharge, a reduction in water quality through the transport of pollutants, a loss of riparian areas, and ultimately a degradation of the watershed’s ecological habitat. It is imperative that actions be taken to protect it from further deterioration and restore the ecosystem to the greatest extent possible.

While urbanization and impervious surfaces are the primary stressors for the overall Anacostia River watershed, there is regional variation throughout the watershed and as such, the extent and source of the environmental stressors as well as potential restoration actions will be evaluated on a subwatershed basis. As part of the Anacostia Restoration Plan (ARP) study, each of the 14 primary subwatersheds and the Tidal Anacostia River reach were evaluated in order to determine problems and opportunities at the subwatershed scale for environmental or ecological restoration, and present this information in such a way that would be beneficial to several different audiences. In addition, for each of the 14 primary subwatersheds and the Tidal Anacostia River reach, a SWAP, an environmental baseline conditions report, and a subwatershed provisional restoration project inventory was generated.

The purpose of the Sligo Creek SWAP is to provide a vision statement and targets for restoration within the subwatershed by the year 2020, identify and describe specific problems within the subwatershed, discuss methodologies used to evaluate potential restoration opportunities, and present a prioritized list of restoration opportunities for implementation.

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The identification of restoration opportunities and potential projects were based on the following selected strategies:

1. Stormwater Management Retrofits 2. Stream Restoration 3. Wetland Creation and Restoration 4. Fish Blockage Removal/Modification 5. Riparian Reforestation, Meadow Creation, Street Tree, and Invasive Species Management 6. Trash Reduction 7. Toxic Remediation 8. Parkland Acquisition

Building upon the preceding eight restoration strategies, the following 2020 restoration objectives align with and expand upon the existing Anacostia River watershed restoration goals and requirements established by the Anacostia Watershed Restoration Partnership (AWRP):

1. Stormwater Management: Implement stormwater retrofits or Best Management Practices (BMPs) to reduce pollutant loading and increase flow regime stability. Increase use of homeowner BMPs throughout the subwatershed. 2. Wetland Creation and Restoration: Increase wetland habitat throughout the subwatershed. 3. Riparian Corridors: Increase the health of riparian corridors so as to both improve wildlife habitat connectivity and reduce the number of invasive plant problem sites. Also, increase overall tree canopy coverage throughout the subwatershed. 4. Aquatic Community: Increase the health of the aquatic community; specifically increase the number of resident fish species and provide for a healthier macroinvertebrate community food base. Restore migratory fish usage of Sligo Creek. 5. Trash Reduction: Dramatically reduce trash loads in Sligo Creek. 6. Outreach: Increase participation of residents, businesses, and school-age children in activities that are beneficial to the watershed. 7. Parkland Acquisition: Increase parkland and habitat connectivity

10-Year Vision

The Sligo Creek subwatershed vision is to create, by the year 2020, a more environmentally healthy and sustainable watershed by dramatically reducing stormwater runoff volumes, stream channel erosion problems, trash levels and pollutant loadings; protecting and restoring aquatic and terrestrial habitats and associated biological communities; enhancing watershed recreational opportunities; and fully engaging both public and private sectors through expanded environmental education and incentive-based initiatives. The preceding objectives are a continuation of and expansion on the AWRP’s existing Anacostia River watershed goals, leading to the achievement of realistic and attainable restoration targets within the next decade.

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Sligo Creek 2020 Targets

The Sligo Creek 2020 Restoration Targets were determined based on the potential implementation of restoration opportunities identified within the Sligo Creek subwatershed as part of the ARP, along with realistic expectations of what could be accomplished in ten years to meet the 2020 restoration objectives. These targets are established to ensure that restoration of the subwatershed is proceeding in the right direction and at a continuous, reasonable pace. The analysis presented in this SWAP will help to establish specific target levels of restoration for the subwatershed. Quantitative targets established such as stormwater management, aquatic community, trash reduction, wetland creation/restoration, riparian corridor restoration, and land acquisition, will be based on the potential restoration project inventory and recommend acreages or mileages to be restored, whereas the qualitative targets including environmental programs and public outreach will recommend programmatic actions that will serve to increase public awareness and interest in the restoring the Anacostia watershed. The 2020 Restoration Targets are presented in Section 4 of this SWAP.

Existing Conditions in the Sligo Creek Subwatershed

Sligo Creek is a free flowing (nontidal) tributary of the Northwest Branch of the Anacostia River; the stream joins Northwest Branch at the western city limits of Hyattsville, Maryland (Figure 1-2). Major tributaries to Sligo Creek include Wheaton Branch, Flora Lane Tributary, Woodside Park Tributary, Long Branch and Takoma Branch.

The Sligo Creek subwatershed, which has a drainage area of 11.1 square miles (or approximately 7,085 acres), is located in the central western vicinity of the Anacostia River watershed (Figures 1-2 and 1-3). The subwatershed is located within Montgomery and Prince George’s Counties, Maryland and the District of Columbia, with approximately 75-percent of its area located in Montgomery County, Maryland. Elevations in the Sligo Creek subwatershed range from 450 feet at the watershed drainage divide to 35 feet at the confluence with Northwest Branch. Sligo Creek has an average gradient of 0.72-percent over 8.3 miles of its main stem length. Average base flow for the lower Sligo Creek main stem is estimated to be approximately 5 to 6 cubic feet per second. Sligo Creek flows from its headwaters in the Piedmont physiographic province into the Coastal Plain. There are approximately 33 acres of wetlands in Sligo Creek, with the majority being of the Palustrine classification. The entire lower mainstem channel, from Riggs Road to the confluence with Northwest Branch, has been channelized. In addition, major portions of the Sligo Creek mainstem from University Boulevard downstream to Maple Avenue, have been armored with rip-rap to reduce streambank erosion.

Approximately 81,950 people reside within the subwatershed with an approximate population density of 7,081 people per square mile. Less than 10-pecent of the subwatershed is undeveloped, and Sligo Creek is one of the most heavily urbanized and older developed tributaries of the Anacostia River watershed. The largest land uses by area in the Sligo Creek subwatershed are (1) medium density, single-family residential (2) forest cover, and (3) commercial. There are 18,677 single-family homes in the watershed. Impervious surfaces cover approximately 34-percent (2,375 acres) of the subwatershed and approximately 505 of those impervious acres (21-percent), have stormwater management controls using Best Management

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Practices (BMPs) with the greatest proportion, nearly 48-percent, within the upper portion of the subwatershed.

Table 1-1 and Figure 1-1 present a summary of the impervious surfaces within Sligo Creek subwatershed. Table 1-2 summarizes the current level of stormwater control of impervious areas within the Sligo Creek subwatershed.

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FigureImpervious 1-1: Impervious Acres in Acres Sligo in Creek Sligo Subwatershed Creek Subwatershed

15% 33% Roads Parking Lots 36% Roofs 16% Other

Table 1-1: Impervious Surfaces in the Sligo Creek Subwatershed and Existing Level of Control Miles Acres Roads 204 795.2 State/Federal 21.4 186.8 Local 182.6 608.4 Parking Lots … 383.3 Public/Institutional … 205.6 Private … 177.7 Roofs … 846.7 Public/Institutional … 172.6 Private … 146.5 Single Family … 527.6 Other … 350.0 Sidewalks … 88.5 Single Family Driveways … 261.5

Total Impervious Acres 2,375.2 Total Subwatershed Acres 7,085.4 Avg. % Imperviousness 33.6

Current Impervious Acreage 505 Controlled Current-percent of Impervious 21% Acreage Controlled Number of existing BMPs 87

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Figure 1-2: Sligo Creek Subwatershed

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Figure 1-3: Sligo Creek Subwatershed Planning Units

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Figure 1-4: Sligo Creek Subwatershed BMP Locations

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Problems Facing the Sligo Creek Subwatershed

Changes to Hydrology The development of the Sligo Creek subwatershed has altered the hydrology and flow regime, and is a major cause for other problems facing the subwatershed. The change in land cover from forest or agriculture to impervious surfaces (such as roofs, roads, and parking lots) has set up a dynamic in which stormwater runoff increases and infiltration of precipitation into soils decreases. An increase in stormwater runoff increases peak discharge that provides energy necessary to erode stream banks as well as discharging pollutants from overland sources into receiving streams. Moderate to severe stream channel erosion was documented in the upper main stem north of University Boulevard, the Breewood Local Park Tributary, the Flora Lane Tributary, Takoma Branch and the Raydale Road Tributary.

Poor Aquatic Habitats As with many developed watersheds, the biological characteristics of the streams in this subwatershed are far less than ideal for the support of healthy ecosystems. Only about 35- percent of the stream miles have adequate riparian buffers (total width of 300 feet). IBI data for fish and amphibian populations in the mainstem are impacted, scoring no better than 36-percent, or moderately impaired. The upper section of Sligo Creek, however, has improved fish and macroinvertebrate populations since the completion of the first two phases of habitat restoration, including stormwater management quality and quantity control retrofits, in-stream habitat restoration of the mainstem, reforestation, and wetland creation along with native fish and amphibian reintroductions. The aquatic habitat rankings scored greater than 70-percent, or partially supporting, of reference conditions at three mainstem sampling sites.

There are multiple physical barriers to fish movement in the subwatershed. Several barriers exist downstream of Riggs Road, which impedes resident and anadromous fish movement and migration. Many of these blockages are a result of channelization, perched culverts, utility crossings, and enclosed stream sections. Fifty-seven fish barriers currently remain in the Sligo Creek subwatershed. The Sligo Creek Environmental Baseline Conditions and Restoration Report contains additional information on the locations of the fish barriers and IBI data for the subwatershed.

Poor Water Quality Water quality also plays a major role in the problems facing the Sligo Creek subwatershed. Approximately 90-percent of the subwatershed is developed and only approximately 15-percent remains forested. Non-point source pollution from impervious surfaces affects water quality within the subwatershed. With the exception of the upper section of the Sligo Creek subwatershed, the area was developed prior to the era of mandatory stormwater controls. Eight- seven BMP provide controls to roughly 505 total acres of impervious surfaces. The high level of imperviousness, inadequate numbers of stormwater management controls (especially in the middle and lower sections), as well as general moderate stream channel erosion have all contributed to poor water quality within the Sligo Creek subwatershed. The TSS load for overland contributions from impervious surfaces is estimated to be approximately 864 tons/square mile/year. The nutrient loading rates associated with this are presented in Table 1-2. The sediment Total Maximum Daily Load (TMDL) analysis for the Anacostia River estimates

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that approximately 70-percent of the sediment loaded into the tidal estuary originates from the stream banks and channels.

Toxics, which include trace metals, polycyclic aromatic hydrocarbons (PAH), polychlorinated biphenyls (PCB), pesticides, and herbicides, enter the surface waters of the subwatershed via runoff (non-point source) and industrial/municipal discharge. There has been minimal data collected to determine the extent and source of the toxics that are present in the Sligo Creek subwatershed. One study used active bio-monitoring to attempt to locate sources of PCB, PAH, and chlordane, which identified the presence of elevated levels of chlordane PAH near the Capitol Beltway Intersection and downstream of the Montgomery and Prince George’s County boundary (Phelps, 2007). There are a total of 119 National Pollutant Discharge Elimination System (NPDES) related discharges in the Anacostia watershed and eight of them are located within the Sligo Creek subwatershed. Figure 1-5 shows the location of NPDES sites in the Anacostia watershed. One Resource Conservation and Recovery Act (RCRA) site is located in the Sligo Creek subwatershed (Figure 1-6). No Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) sites are located within this subwatershed.

The available fecal coliform sampling for Anacostia River watershed suggests that streams in the watershed do not meet established bacterial water quality standards. While this data is not specifically available for the Sligo Creek subwatershed, studies done in other subwatersheds of the Anacostia River have shown that bacterial contamination is contributed to the subwatershed by the following sources: human (9 to 55-percent), domestic animals (24 to 28-percent), livestock (6 to 28-percent), and wildlife (12 to 38-percent). As a result of the requirement for Washington Sanitary Sewer Commission (WSSC) to rehabilitate its sewer line system in Maryland and develop a water quality management plan, there is now one monitoring station located on Sligo Creek.

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Figure 1-5: NPDES Sites in the Anacostia River Watershed

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Figure 1-6: RCRA Sites in the Anacostia River Watershed

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Trash Trash is another non-point source contaminant entering the system. Trash surveys have indicated areas experiencing moderate to high trash levels include Wheaton Branch upstream of Dennis Avenue, Flora Lane Tributary, Long Branch downstream of Piney Branch Road, Takoma Branch downstream of Ray Road, Raydale Road Tributary and the lower Sligo Creek mainstem downstream of East-West Highway.

Further data and discussion regarding the current conditions of the Sligo Creek subwatershed can be found in the Anacostia Watershed Baseline Conditions and Restoration Report prepared by MWCOG.

Flooding Flooding has been a long-standing problem throughout the Anacostia River watershed, particularly in Prince George’s County, though areas of Montgomery County and the District of Columbia experience episodic flooding as well. Prince George’s County is prone to flooding because the county is located within the Coastal Plain physiographic province, which is generally wider and flatter, and due to development of floodplains prior to the development of stormwater management regulations and controls. Periodic flooding within Sligo Creek occurs primarily within the middle and lower portions of the subwatershed along the Sligo Creek mainstem for which an earthen levee was constructed parallel to Sligo Parkway on the east bank, downstream of Riggs Road.

Further data and discussion regarding the current conditions of the Sligo Creek subwatershed can be found in the Anacostia Watershed Environmental Baseline Conditions and Restoration Report prepared by Metropolitan Washington Council of Governments (MWCOG).

Existing Pollutant Loads

Existing pollutant loadings for sediment, nitrogen (N), and phosphorous (P) was calculated for the Anacostia River watershed TMDL by the Maryland Department of the Environment (MDE). As part of the ARP, the sediment, N, and P loadings were calculated for the Sligo Creek subwatershed using the same loading rates per land use for the TMDL in order to estimate the Sligo Creek subwatershed’s contribution of pollutant load to the overall Anacostia River load (Kim et al, 2007; Mandel et al, 2008). The Anacostia River watershed TMDL identifies a reduction goal for sediment, N, and P as 85-, 79-, and 80-percent, respectively. By knowing the percent reduction necessary for the entire Anacostia River watershed and applying the percent reduction to the Sligo Creek subwatershed pollutant loading estimate, the subwatershed loading reduction for Sligo Creek necessary to achieve the overall Anacostia River watershed TMDL can be estimated. Additional information is available on the existing pollutant loading calculations is available in the Plan Formulation appendix to the Anacostia Watershed Restoration Plan and Report.

Identifying the existing magnitude of loadings on a subwatershed basis allows for the ability to geographically target and evaluate the scale of restoration needed to reduce N, P, and sediment inputs within each subwatershed to attain goals. A summary table of Sligo Creek subwatershed current loadings and how they compare to the rest of the Anacostia River watershed is found in

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Table 1-2. The efforts to attain TMDLs are being led by the U. S. Environmental Protection Agency (EPA) and MDE, and as such neither this SWAP nor the ARP are intended to serve as TMDL implementation plans, although data presented here may contribute to that effort. The Plan Formulation appendix of the Anacostia Watershed Restoration Plan and Report provides more details regarding the methodology used to obtain the current loading estimates and presents the results of those analyses. It must be noted that the analyses conducted for the ARP in regards to pollutant reduction only considered overland flow, and does not account for pollutant contribution from the stream channel itself, namely sediment from erosion. Additional detailed modeling would be required to determine sediment transport change associated with reduced runoff volumes from implementation of the stormwater management retrofit projects identified in the ARP.

Table 1-2: Nutrient Loading Estimates for Sligo Creek Subwatershed and Comparison Values TSS Nitrogen Phosphorus tons/sq lbs/sq mi/year lbs/sq mi/year mi/year Sligo Creek 57,718 5,198 864 Average Anacostia 5,255 500 99 Subwatershed Completely Value not Forested 42 8 calculated Watershed

Table 1-3: TMDL Reduction Goals Nitrogen Phosphorus TSS tons/sq lbs/sq lbs/sq mi/year mi/year mi/year Anacostia River Watershed TMDL 79% 80% 85% Reduction Goals

Estimated Sligo Creek 57,718 5,198 864 Loadings Estimated Sligo Creek Reduction Goal as Pro- 45,598 5,198 734 Rated Share of Anacostia TMDL Goals

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Section 2 Inventory of the Provisional Restoration Candidates

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Inventory of the Provisional Restoration Candidates

As part of the ARP study, a systematic process was developed to identify, catalog, and evaluate each restoration opportunity. In addition, the evaluation of restoration projects was completed by using a detailed system to score the various projects and ultimately determine a ranking of projects. The opportunities presented were identified through the compilation of existing data, input from local jurisdictions, GIS analyses, and field observations. The existing data provided by the local municipalities included land use data, public/private ownership information, impervious surfaces data, planning department classifications, digital elevation models, stormwater management data, and aerial photographs. A detailed explanation of the methodology utilized to identify the opportunities can be found in the Plan Formulation appendix to the Anacostia Watershed Restoration Plan and Report.

In addition to the restoration strategies discussed in Section 1, the potential projects identified as part of this analysis are intended to achieve one or more of the following 2020 restoration objectives:

1. Stormwater Management 2. Wetland Creation and Restoration 3. Riparian Corridors 4. Aquatic Community 5. Trash Reduction 6. Outreach 7. Parkland Acquisition

Table 2-1 identifies potential project types per objective, gives a brief description, and states the metric that will be used.

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Table 2-1: 2020 Sligo Creek Restoration Objectives

Objectives Description of Objective Metric

Stormwater Management

Retrofit current stormwater controls, utilize Acres Controlled and Pounds of N, bioretention, filters, bioswales, wet ponds, wetlands P, TSS loading reduced Retrofits, ESD, Low Impact to add controlled acreage to the subwatershed Development (LID)

Include use of Green roofs, disconnects, rain Acres Controlled and Pounds of N, barrels, permeable pavement, and rain gardens P, TSS loading reduced Homeowner BMPs

Trash Reduce trash through use of netting, catching, and Number of Projects Implemented / Implement reduction projects grates MWCOG Trash Index Rating Acres Swept and Pounds of N, P, Increase street sweeping programs Street Sweeping TSS loading reduced

Aquatic Community Restore fish habitat through improved water quality Index of Biotic Integrity Rating IBI Rating for Fish and flow management Restore macroinvertebrate habitat through IBI Rating for Index of Biotic Integrity Rating Macroinvertebrate improved water quality and flow management Fish Passage Remove barriers to fish migration Miles of Stream

Wetland Creation and Restoration Create new wetlands and vernal pools and Acreage created or restored Create and Restore Acreage restore/expand existing ones

Riparian Corridors Invasive Species Management Removal of invasive species from the corridor Acres managed Reforestation Replanting of the riparian corridor Acres reforested Increase Tree Canopy Tree planting in both urban and non-urban areas Acres / % increase

Outreach / Public

Involvement Educate the public about BMPs and encourage Increase participation of Qualitative residents and businesses their use of them Establish a subwatershed group to facilitate public Establish Friends of Sligo Yes or No Creek Organization involvement Expand current programs and encourage businesses to offer incentives. Assist private Expanded or Maintained Incentive Programs owners with measures such as rain barrels.

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A total of 170 potential restoration candidate projects within the Sligo Creek subwatershed have been identified as part of the ARP investigation. The complete inventory and description of the 170 proposed projects are included in Project Inventory section of this appendix. The potential restoration projects address five of six restoration strategies identified for the Sligo Creek 2020 restoration objectives (does not include projects for increasing participation). The presence of elevated levels of toxic contaminants has been identified in Sligo Creek; however, detailed studies have not been completed to identify the exact sources and extent of the problem, and thus there are no provisional restoration candidate projects that address toxics in the report. It is recommended that further studies regarding the source and extent of toxic contamination should be undertaken by the appropriate authorities. In addition to illicit discharges, historic dump sites may be sources of toxic contaminants in the system. A diagram of these sites and current NPDES sites can be found in Section 1 of this subwatershed action plan on Figures 1-3 and 1-4.

Tables 2-2, 2-3, and 2-4 provide a summary of the proposed restoration project types, quantity, and the estimated cost of implementation. It should be noted that the development of the NPDES MS4 permit by the three local jurisdictions may or may not include provisional restoration projects presented in the SWAP or Subwatershed Provisional Restoration Projects Inventory.

Table 2-2: Inventory of Restoration Projects in the Sligo Creek Subwatershed Additional Length Acreage Number Impervious Restored Restored Estimated Candidate Project Type of Acreage or or Cost ($) Projects Controlled Managed Created (ac) (mi) (Ac) Stormwater Retrofit 83 34,986,385 249.7 - - Stream Restoration 13 6,820,000 3.0 - Wetland Creation/ Restoration/Vernal Pools 12 92,000 - - 1.8 Fish Blockage Removal / Modification 23 3,237,000 11.5 Riparian Reforestation / Riparian Invasive Management / Meadow Planting 17 21,900 - - 15.9 Trash Reduction 21 114,775 - - - Toxic Remediation -- -- - Parkland Acquisition 1 50,000 - - 0.5 Total 170 45,322,060 249.7 34.4 18.2

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Table 2-3 Proposed Restoration by Type in the Sligo Creek Subwatershed Project Type Watershed Area Total New Acreage for Stormwater Upper Middle Lower Total Projects Wetland and Wet Pond Stormwater (acres)* 20.8 2.07 0.0 22.9 22.9 Bioretention (acres)* 55.5 60.8 56.0 172.3 172.3 Bioswales (acres)* 1.67 0.0 0.0 1.7 1.7 Permeable Pavement (acres)* 6.02 2.55 1.0 9.6 9.6 Filter (acres)* 4.8 7.2 0.0 12.0 12.0 Green Roof (acres)* 4.88 5.13 2.0 12.0 12.0 Downspout Disconnect (acres)* 3.12 4.23 1.0 8.4 8.4 Rain Barrels (acres)* 3.12 0.0 1.0 4.1 4.1 Rain Garden (acres)* 3.12 1.03 2.0 6.2 6.2 Infiltration Practices (acres)* 0.0 0.0 0.0 0.0 0.0 Pipe Storage (acres)* 0.0 44.0 0.0 44.0 44.0 Gully Erosion Control (acres)* 1.4 0.0 0.0 1.4 0.0 Pipe/Weir Modification (acres)* 411.4 0.0 0.0 411.4 0.0 Swale Modification (acres)* 0.5 0.0 0.0 0.5 0.5 Invasive Species Management (acres) 0.6 1.5 2.5 4.6 N/A Riparian Reforestation (acres) 0.7 0.0 0.0 0.7 N/A Upland Reforestation (acres) 0.4 0.0 0.0 0.4 N/A Meadow Planting(acres) 0.2 0.0 10.0 10.2 N/A Wetland Restoration (acres) 0.0 0.1 0.5 0.6 N/A Vernal Pools Restoration/Creation (acres) 0.5 0.15 0.55 1.2 N/A Parkland Acquisition (acres) 0.0 0.0 0.5 0.5 N/A Stream Restoration (miles) 1.4 0.6 1.0 3.0 N/A Fish Passage (miles) 3.1 4.3 4.1 11.5 N/A Street Sweeping (miles) 7.1 6.44 5.8 19.3 N/A Trash Reduction (number of projects) 5 5 11 21 N/A

*Note: Acreage shown represents the total acreage controlled by the project. A portion of these are retrofits and upgrades, therefore the acreage is not representative of ‘new’ acreage controlled but represents new and current acreage controlled by the proposed project. The newly controlled acreage is in the last column.

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Table 2-4: Provisional Restoration Project Estimated Unit Costs No. Practice Approximate Unit Cost ($)

Stormwater Retrofit Existing Stormwater Management Pond/Wetland $1,000-$3,000/acre of drainage 1 Retrofitting New Stormwater Management $3,000-$5,000/acre of drainage 2 Pond/Wetland Construction LID-Bioretention with Under Drain $100,000/impervious acre 3 System $100,000/impervious acre 4 LID-Curbside/Street Planter $54,450-$65,340/impervious acre 5 LID-Tree box filter $42/square foot 6 LID-Green Roof LID-Single Family Home Rain $5,000 per individual garden 7 Garden LID-Single Family Home Rain $200/barrel (typically two per house) 8 Barrel $20,000 to $25,000 per impervious acre 9 Sand Filter $15,000/impervious acre 10 Underground Pipe Storage $4.0/square foot 11 Permeable Pavement

Stream Restoration/Fish Passage Blockage Removal or Modification $300/linear foot 12 Stream Restoration Concrete Stream Channel $1,000/linear foot 13 Removal $2,000/linear foot 14 Stream Day Lighting Fish Passage/Riffle Grade $150,000/one foot barrier height 15 Control Structure $50,000/acre 16 Wetland Creation

Trash Reduction/Water Quality $1,000/acre of drainage 17 Trash Netting System End-of-Pipe Trash Catching $4,000/acre of drainage 18 System $50/curb mile 19 Street Sweeping $500/inlet 20 Storm Trash Grate

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Results of the Evaluation and Scoring of Restoration Actions in Sligo Creek Subwatershed

To recommend restoration action and to determine the sequence for implementation, the quantitative scoring scheme was used to evaluate the 170 provisional restoration candidate projects. This common scoring system allowed for comparison of candidates across as well as within the restoration strategies. The scores for all 170 projects ranged from 88 to 51 points out of a possible 100. To prioritize among projects based on benefits, the scores were divided into three tiers based on the distribution of the scores, with Tier I projects being those anticipated to provide the greatest potential benefits. Tier I includes projects that scored an 80 or above, Tier II includes projects that scored anywhere from 79 to 65, and Tier III includes those that scored 64 or below. Further discussion on the scoring system for the proposed projects can be found in the Plan Formulation appendix to the Anacostia Watershed Restoration Plan and Report.

The scoring scheme for the provisional stormwater management candidate projects was subsequently further adjusted. The tier system was retained, but the tier boundaries were refined based on distribution of the adjusted score as described in the stormwater management subsection below.

The following tables present the scores and overall rank of the provisional restoration actions for the Sligo Creek subwatershed separated by restoration strategy.

Stormwater Management To provide for better differentiation for potential benefits that would be produced by the 69 potential stormwater management candidate projects and aid the local communities in prioritization for implementation, the scoring system used for project candidates in this restoration strategy were adjusted from the common scoring system. Variables representing two additional factors unique to stormwater management were incorporated into the scoring system: unit imperviousness and existing stormwater control. Data for these variables was obtained from MWCOG and is presented in the Sligo Creek Environmental Baseline Conditions and Restoration Report. In the adjusted scoring system for the stormwater projects, Tier I includes projects above 100, Tier II includes projects that are between 89 and 99, Tier III are those scored 88 and below, and Tier IV are those projects that did not meet the minimum requirements to be included in the adjusted scoring system but could still be considered as restoration opportunities in the future. Further explanation of the basis for the adjusted scoring can be found in the Plan Formulation appendix to the Anacostia Watershed Restoration Plan and Report. The top 20 stormwater retrofit candidate projects are listed in Table 2-5. Additional information and project descriptions can be in the Sligo Creek Subwatershed Provisional Restoration Projects Inventory.

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Table 2-5: Top 20 Potential Stormwater Retrofit Projects within the Sligo Creek Subwatershed

Overall Rank Adjusted based Estimated Project ID Project Name Score on Cost ($) Original

Jurisdiction* Scoring Chillum Place (Sligo Mill Road to Underwood SC-L-01-S-1 DC Street) 115.3 2 1,700,000 Riggs Rd (Fair Oak Ave to E/W Highway) SC-L-01-S-13 PG 'Green Street' 107.5 7 750,000 SC-M-01-S-14 MC Long Branch Community Center 105.3 3 272,000 SC-M-01-S-15 MC Rolling Terrace ES 97.3 34 3,057,232 SC-U-01-S-31 MC Woodside Park 97.2 25 220,000 SC-M-01-S-10 MC Flower Avenue Shopping Center 96.7 72 700,000 US RTE 29 @ Capital Beltway Interchange SC-M-01-S-2 MC (~1,800 LF) 96.0 62 664,000 SC-M-01-S-17 MC Takoma Academy 95.9 68 736,000 SC-M-01-S-22 MC Takoma Park Middle School 94.3 48 623,000 SC-U-01-S-11 MC University BLVD Median Strip (~6,000 LF) 94.1 48 1,000,000 SC-U-01-S-8 MC Glen Haven Elementary School 93.7 23 260,000 SC-L-01-S-14 PG Riggs /Sargent Shopping Center 93.5 102 850,000 SC-L-01-S-8 PG Takoma Park Plaza 92.9 72 204,800 SC-L-01-S-7 PG Redtop Road 92.8 86 112,500 SC-M-01-S-9 MC Oakview ES 91.3 72 306,000 SC-M-01-S-3 MC University Blvd/Capital Beltway Cloverleaf 90.3 86 245,000 WMATA-Takoma Metro Station Parking Lot & SC-M-01-S-23 DC Bus Lanes 88.3 102 333,000 SC-M-01-S-27 MC Hastings Drive 'Green Street' 88.2 115 480,000 SC-U-01-S-18 MC Northwood H.S. 88.1 102 1,030,000 SC-L-01-S-4 DC Hampshire Knoll Neighborhood 85.9 136 50,000 TOTAL 13,593,532 *MC=Montgomery County, Maryland PG=Prince George’s County, Maryland DC=Washington D.C. Scoring Tier = Tier I, Tier II, Tier III

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In order to allow for more regional prioritization, the top five stormwater projects for each of the planning units in the subwatershed (Upper, Middle, Lower) are in Tables 2-6, 2-7, and 2-8.

Table 2-6: Top 5 Potential Stormwater Retrofit Projects within the Upper Sligo Creek Subwatershed

Overall Rank Adjusted based Estimated Project ID Project Name Score on Cost ($) Original

Jurisdiction* Scoring SC-U-01-S-31 MC Woodside Park 97.2 25 220,000 SC-U-01-S-11 MC University BLVD Median Strip (~6,000 LF) 94.1 48 1,000,000 SC-U-01-S-8 MC Glen Haven Elementary School 93.7 23 260,000 SC-U-01-S-18 MC Northwood H.S. 88.1 102 1,030,000 SC-U-01-S-20 MC Dennis Ave. Median 85.7 72 255,000 TOTAL 2,765,000 *MC=Montgomery County, Maryland Scoring Tier = Tier I, Tier II, Tier III

Table 2-7: Top 5 Potential Stormwater Retrofit Projects within the Middle Sligo Creek Subwatershed

Overall Rank Adjusted based Estimated Project ID Project Name Score on Cost ($) Original

Jurisdiction* Scoring SC-M-01-S-14 MC Long Branch Community Center 105.3 3 272,000 SC-M-01-S-15 MC Rolling Terrace ES 97.3 34 3,057,232 SC-M-01-S-10 MC Flower Avenue Shopping Center 96.7 72 700,000 US RTE 29 @ Capital Beltway Interchange SC-M-01-S-2 MC (~1,800 LF) 96.0 62 664,000 SC-M-01-S-17 MC Takoma Academy 95.9 68 736,000 TOTAL 5,419,232 *MC=Montgomery County, Maryland Scoring Tier = Tier I, Tier II, Tier III

Sligo Creek Subwatershed Plan 31

Table 2-8: Top 5 Potential Stormwater Retrofit Projects within the Lower Sligo Creek Subwatershed

Overall Rank Adjusted based Estimated Project ID Project Name Score on Cost ($) Original

Jurisdiction* Scoring Chillum Place (Sligo Mill Road to Underwood SC-L-01-S-1 DC Street) 115.3 2 1,700,000 Riggs Rd (Fair Oak Ave to E/W Highway) 'Green SC-L-01-S-13 PG Street' 107.5 7 750,000 SC-L-01-S-14 PG Riggs /Sargent Shopping Center 93.5 102 850,000 SC-L-01-S-8 PG Takoma Park Plaza 92.9 72 204,800 SC-L-01-S-7 PG Redtop Road 92.8 86 112,500 TOTAL 3,617,300 *DC=Washington D.C. PG=Prince George’s County, Maryland Scoring Tier = Tier I, Tier II, Tier III

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Stream Restoration All of the 13 potential stream restoration candidate projects are presented in Table 2-9. Lengths of the stream restoration projects ranged from approximately 250 to approximately 2,400 feet. Additional project description information can be found in the Project Inventory section of this appendix.

Table 2-9: Potential Stream Restoration Projects within the Sligo Creek Subwatershed

Overall Estimated Project ID Project Name Score Rank Cost ($) Jurisdiction*

SC-U-02-SR-1 MC Upper Sligo Mainstem (Above Univ. Blvd SWM Facility) 74 34 720,000 SC-M-02-SR-2 MC Greenbrier Drive Tributary @ Sligo Creek Park 71 48 90,000 SC-L-02-SR-1 PG Ray Road to Red Top Road 71 48 396,000 SC-L-02-SR-4 PG Sligo Mainstem (19th Place to Roanoake St) 69 68 612,000 Middle Sligo Mainstem (Worth Ave. to Pershing Dr. SC-M-02-SR-1 MC Area) 68 72 300,000 SC-M-02-SR-3 MC Parkside Road Tributary 67 86 390,000 SC-L-02-SR-3 PG Raydale Road Trib (Open Section) 67 86 252,000 SC-U-02-SR-3 MC Breewood Local Park Tributary 66 96 360,000 SC-U-02-SR-2 MC Colt Terrace Tributary 64 115 510,000 SC-U-02-SR-5 MC Woodside Park Tributary (Lower) 64 115 150,000 SC-L-02-SR-2 PG Red Top Road to Chillum Manor Road 63 122 540,000 SC-L-02-SR-5 PG Prince George's Aveneue Park 63 122 500,000 SC-U-02-SR-4 MC Woodside Park Tributary (Upper) 61 136 2,000,000 TOTAL 6,820,000 *MC=Montgomery County, Maryland PG=Prince George’s County, Maryland Scoring Tier = Tier I, Tier II, Tier III

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Wetland Creation or Restoration All of the wetland restoration candidate projects are presented in Table 2-10. These projects included wetland and vernal pool creation or enhancement. Additional project description information can be found in the Project Inventory Section of this appendix.

Table 2-10: Potential Wetland Creation or Restoration Projects within the Sligo Creek Subwatershed

Overall Estimated Project ID Project Name Score Rank Cost ($) Jurisdiction SC-L-03-W-2 PG M-NCPPC Chillum Park/16th Avenue Wetland Creation 65 102 30,000 SC-L-03-W-1 PG M-NCPPC Lower Sligo-WTOP Transmitter Area 64 115 30,000 SC-U-03-W-2 MC Sligo Mainstem-WSSC ROW Area # 1 63 122 1,000 SC-M-03-W-1 MC Greenbrier Drive Tributary @ Sligo Creek Park 62 133 5,000 SC-U-03-W-5 MC Breewood Local Park Tributary 61 136 500 SC-L-03-W-5 PG Red Top Road to Chillum Manor Road 61 136 1,000 Sligo Creek Foot Trail Vernal Pool (Three Oaks Dr- SC-M-03-W-2 MC Schuyler Rd Area) 57 155 10,000 SC-L-03-W-3 PG Pepco ROW from Ray Road to East/West Highway 57 155 10,000 SC-L-03-W-4 PG Takoma Branch Ray Road to Red Top Road 55 162 1,500 SC-U-03-W-3 MC Sligo Mainstem-WSSC ROW Area #2 54 165 1,000 SC-U-03-W-4 MC Sligo/Colt Terr- Hiker Biker Trail 54 165 1,000 SC-U-03-W-1 MC Channing Drive/M-NCPPC 53 167 1,000 TOTAL 92,000 *MC=Montgomery County, Maryland PG=Prince George’s County, Maryland Scoring Tier = Tier I, Tier II, Tier III

Sligo Creek Subwatershed Plan 34

Fish Blockage Removal or Modification All of the fish blockage removal or modification candidate projects are presented in Table 2-11. The length of stream opened range from approximately 400 feet to approximately 1.7 miles. Additional information regarding the project descriptions can be found in the Project Inventory Section of this appendix.

Table 2-11: Potential Fish Blockage Removal or Modification Projects within Sligo Creek Subwatershed

Overall Estimated Project ID Project Name Score Rank Cost ($) Jurisdiction

SC-U-04-F-3 MC Sligo Mainstem- Log Drop ~300 ft above Brunett Ave 75 25 1,000 SC-U-04-F-5 MC Wheaton Branch- Log Drop 73 40 1,000 SC-M-04-F-1 MC Sligo Mainstem- Log Drop ~500 ft below Colesville Road 73 40 500 Sligo Mainstem- WSSC Sewer Line ~500 ft Below SC-M-04-F-3 MC Wayne Ave 73 40 375,000 SC-U-04-F-2 MC Sligo Mainstem- Log Drop above Flora Lane Trib. 72 45 1,000 SC-U-04-F-6 MC Flora Lane Tributary/Hiker BikerTrail Culvert 71 48 15,000 Sligo Mainstem - 12 in. DIP ~100 LF above Bennington SC-M-04-F-2 MC Dr. Trib. 71 48 8,000 Sligo Creek Mainstem - S0 ~ 700 ft. Upstream of NW Br. SC-L-04-F-1 PG confluence 71 48 150,000 Sligo Creek Mainstem - S3 (behind Green Meadows SC-L-04-F-2 PG Com. Rec. Ctr.) 71 48 75,000 SC-L-04-F-3 PG Sligo Creek Mainstem - S5 (Riggs Road) 71 48 150,000 Sligo Creek Mainstem - S7 (280 ft downstream of E/W SC-L-04-F-5 PG Hwy) 71 48 150,000 Sligo Mainstem- 12 in DIP ~800 ft Below Piney Branch SC-M-04-F-4 MC Road 68 72 8,000 SC-M-04-F-6 MC Sligo Mainstem- Historic Weir~ 200 ft Maple Ave Ave 68 72 30,000 SC-U-04-F-4 MC Sligo Mainstem- Log Drop @ Brunett Ave 67 86 15,000 SC-M-04-F-5 MC Devon Road - WSSC Sewer Line 67 86 255,000 Sligo Creek Mainstem - S6 (500 ft upstream of Riggs SC-L-04-F-4 PG Road) 65 102 375,000 SC-M-04-F-8 MC Long Branch- Piney Branch Road Culvert 63 122 337,500 SC-U-04-F-7 MC Breewood Local Park Tributary 61 136 150,000 SC-U-04-F-8 MC Colt Terrace Tributary 59 149 150,000 SC-L-04-F-6 PG Takoma Branch - Chillum Manor Road Culvert 59 149 300,000 SC-U-04-F-1 MC Sligo Mainstem- Univ. Blvd Culvert 55 162 150,000 SC-L-04-F-7 PG Takoma Branch - Downstream of Ray Road 55 162 390,000 SC-M-04-F-7 MC Long Branch - Fortson Street 50 170 150,000 TOTAL 3,237,000 *MC=Montgomery County, Maryland PG=Prince George’s County, Maryland Scoring Tier = Tier I, Tier II, Tier III

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Riparian Reforestation, Meadow Creation, and Invasive Species Management All of the potential riparian reforestation, meadow creation, and invasive species management candidate projects are presented in Table 2-12. Project sizes ranged from approximately 0.1 acre up to approximately 10.0 acres. Additional information regarding the project can be found in the Project Inventory Section of this appendix.

Table 2-12: Potential Riparian Reforestation, Meadow Creation, and Invasive Species Management Candidate Projects within the Sligo Creek Subwatershed

Overall Estimated Project ID Project Name Score Rank Cost ($) Jurisdiction

SC-L-05-R-4 PG Raydale Road Trib (Open Section) 88 1 500 SC-L-05-R-1 PG Chillum Manor Road Area 82 3 500 SC-M-05-R-3 MC Sligo Mainstem - Park Valley Road Area 80 5 500 SC-M-05-R-4 MC Sligo Mainstem - Carroll Ave-Garland Ave 80 5 500 SC-M-05-R-6 MC Long Branch-Community Center Area 78 10 500 SC-L-05-R-2 PG M-NCPPC Lower Sligo-WTOP Transmitter Area 78 10 500 SC-M-05-R-5 MC Long Branch-East Wayne Park 76 23 500 SC-U-05-R-2 MC Ladd Street/M-NCPPC Foot Bridge 75 25 500 SC-U-05-R-4 MC Sligo Mainstem - Forest Glenn Road Area 74 34 6,300 SC-U-05-R-7 MC Woodside Park Tributary 71 48 500 SC-L-05-R-3 PG Pepco ROW from Ray Road to East/West Highway 70 62 5,000 SC-U-05-R-5 MC Sligo Soccer Field Area 69 68 1,000 SC-U-05-R-1 MC Colt Terrace Area 68 72 2,700 SC-U-05-R-6 MC Wheaton Branch 67 86 500 SC-U-05-R-3 MC Windham Lane Area 66 96 900 SC-M-05-R-2 MC Sligo Creek Foot Trail (Three Oaks Dr-Schuyler Rd Area) 65 102 500 SC-M-05-R-1 MC Bennington Drive Tributary Area 64 115 500 TOTAL 21,900 *MC=Montgomery County, Maryland PG=Prince George’s County, Maryland Scoring Tier = Tier I, Tier II, Tier III

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Trash Reduction The provisional trash reduction candidate projects are presented in Table 2-13. These projects include trash removal, community outreach, trash grates, trash fences, and street sweeping. Additional information regarding the project descriptions can be can be found in the Project Inventory Section of this appendix.

Table 2-13: Potential Trash Reduction Projects within the Sligo Creek Subwatershed

Overall Estimated Project ID Project Name Score Rank Cost ($) Jurisdiction*

SC-L-06-T-8 PG New Hampshire Avenue (Peabody Street to University Blvd.) 79 7 4,970 SC-L-06-T-10 PG Riggs Road (Chillum Road to Avalon Place) 79 7 5,230 SC-U-06-T-1 MC Georgia Ave (Arcola Ave to Spring Street) 78 10 4,186 SC-U-06-T-3 MC University Blvd (Georgia Ave to Colesville Road) 78 10 3,447 University Blvd East (Colesville Road to New Hampshire SC-M-06-T-2 MC Avenue) 78 10 3,447 SC-M-06-T-1 MC Capital Beltway (I-495-Colesville Road-University Blvd) 77 16 739 SC-M-06-T-4 MC Carroll Avenue (University Blvd to Eastern Ave) 77 16 2,216 SC-L-06-T-9 PG E/W Highway (New Hampshire Avenue to 23rd Avenue) 77 16 3,930 SC-L-06-T-11 PG Ray Road (New Hampshire Avenue to Riggs Road) 77 16 3,410 SC-U-06-T-2 MC Capital Beltway (I-495-Georgia Ave-Colesville Road) 75 25 1,559 SC-M-06-T-3 MC Piney Branch Road (Sligo Creek Pkwy to University Blvd) 75 25 3,485 SC-M-06-T-5 DC Eastern Avenue (Laurel Ave to 6th St) 75 25 3,485 SC-L-06-T-6 PG Storm Drain Marker 75 25 96 SC-L-06-T-7 PG Storm Drain Stenciling 75 25 300 SC-L-06-T-1 DC Eastern Evenue (Laurel Street to 6th Street) 72 45 3,800 SC-L-06-T-5 PG Various Signage 70 62 1,600 SC-U-06-T-4 MC Flora Lane Tributary-Columbia Blvd SD Outfall Area 66 96 7,000 SC-L-06-T-4 PG Storm Drain Inlet Grates 62 133 8,000 SC-U-06-T-5 MC Woodside Park Tributary 60 146 2,000 SC-L-06-T-2 PG Redtop Road (1 side) 57 155 16,875 SC-L-06-T-3 PG Redtop Road End of Road Device 57 155 35,000 TOTAL 114,775 *MC=Montgomery County, Maryland PG=Prince George’s County, Maryland DC=Washington D.C. Scoring Tier = Tier I, Tier II, Tier III

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Parkland Acquisition The one potential parkland acquisition candidate projects is presented in Table 2-14. The acreage associated with the proposed land acquisition is 0.5 acre. Additional information regarding the project description can be found in the Project Inventory section of this appendix.

Table 2-14: Potential Parkland Acquisition Projects within the Sligo Creek Subwatershed

Overall Estimated Project ID Project Name Score Rank Cost ($) Jurisdiction

SC-L-08-L-1 PG William Ford Property - Parcel 163 63 122 50,000 TOTAL 50,000 *PG=Prince George’s County, Maryland Scoring Tier = Tier I, Tier II, Tier III

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Summary of Recommended Restoration Actions The Recommended Restoration Actions are those that could potentially be implemented and a roll-up of these projects is presented in Table 2-15. Additional information on the descriptions and details of the potential actions can be found in the Sligo Creek Subwatershed Provisional Restoration Projects Inventory.

Table 2-15 Summary of Recommended Potential Restoration Actions

Number of Estimated Candidate Project Type Projects Cost ($)

Stormwater Retrofits Tier I* 4 2,722,000 Tier II* 13 8,978,532 Tier III* 13 6,972,920 Tier IV 53 16,312,933 Stream Restoration Tier I 0 0 Tier II 8 3,120,000 Tier III 5 3,700,000 Wetland Creation / Restoration Tier I 0 0 Tier II 1 30,000 Tier III 11 62,000 Fish Blockage Removal / Modification Tier I 0 0 Tier II 16 1,609,500 Tier III 7 1,627,500

Riparian Reforestation Tier I 4 2,000 Tier II 12 19,400 Tier III 1 500 Trash Reduction Tier I 0 0 Tier II 17 52,900 Tier III 4 61,875 Land Acquisition Tier I 0 0 Tier II 0 0 Tier III 1 50,000 TOTAL 170 45,322,060 *Tiers for the Stormwater Projects Reflect the Adjusted Scoring System

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Implementation Type of Potential Restoration Actions

Restoration opportunities identified as part of the ARP require additional study, design, or policy change prior to implementation. Table 2-16 provides a summary of the number of projects that fall under each of the four implementation types. Design/build projects are likely those projects ready to be implemented, whereas feasibility projects would require additional detailed studies prior to the design phase. The design/build projects can be implemented by local jurisdictions, agencies, non-profit organizations, or through one of the several USACE design/build programs. It should be noted that USACE has been provided authority under various Water Resource Development Acts to complete Design/Build projects in the Anacostia watershed. The projects requiring feasibility studies like stream restoration or wetland creation likely would be projects USACE could implement following the appropriate Civil Works authority, budgeting cycle, and protocol. Projects classified as requiring a programmatic element prior to implementation may require governmental policy changes or authority to purchase land. Finally, stewardship projects are likely those potential projects to be completed by volunteers from local churches, schools, or community watershed groups such as trash pick up, vernal pool creation, riparian reforestation, invasive species eradication, etc.

Additional information regarding what specific projects are classified under each category can be found in the Plan Formulation appendix to the Anacostia Watershed Restoration Plan and Report.

Table 2-16: Summary of Potential Restoration Actions Implementation Types Number Implementation of Estimated Type Projects Cost ($) Design/Build 89 35,056,860 Feasibility 36 10,128,500 Stewardship 33 45,094 Programmatic 12 91,606 TOTAL 170 45,322,060

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Section 3 Evaluation and Discussion of the

Restoration Strategies

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Evaluation of the Restoration Strategies

The proposed restoration projects were evaluated using the approach described in the main report of the ARP. The first step in the evaluation consisted of assessing the potential of the restoration actions to control pollutant loads. As described in the Anacostia Watershed Environmental Baseline Conditions and Restoration Report, the TMDL modeling efforts of Interstate Commission on the Potomac River Basin (ICPRB) and MDE were used to provide the existing pollutant loads, and the Watershed Treatment Model (WTM) was used to estimate the potential pollution reduction achieved by the proposed restoration strategies. The Plan Formulation appendix to the Anacostia Watershed Restoration Plan and Report lists the efficiencies of the various BMPs included in the WTM. It should be noted that the list of stormwater management practices listed in the WTM was expanded to include LID practices. The LID practices included green roofs, rooftop disconnection, rain barrels and cisterns, soil amendments, sheet flow to open space, bioretention, and rain gardens.

The potential restoration strategies were individually evaluated using the WTM to estimate the pollutant reduction benefit the project could provide. The full WTM user guide is available online from the Center for Watershed Protection (CWP) at www.cwp.org.

Potential to Reduce Stormwater Pollutant Loads

The proposed restoration projects would provide additional stormwater controls to 248 impervious acres in the Sligo Creek subwatershed. This represents an 11-percent increase in the acres of impervious surfaces controlled by stormwater management, bringing the total acres controlled by stormwater management up to approximately 753 or 32-percent of the total impervious acres. Table 3-1 summarizes the improvements in stormwater controls after implementation of the proposed projects.

Table 3-1: Level of Stormwater Control in Sligo Creek Subwatershed After Implementation of All Proposed Stormwater Projects Existing Potential Future Stormwater Stormwater Total Increase in Impervious Controls Controls Impervious Acreage Controlled by % of % of Acres Stormwater Projects Acres Impervious Acres Impervious Total Total

2,375 505 21% 753 32% 11%

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Table 3-2: Evaluation of Stormwater Control Levels and Potential in Pollutants Load Reduction Pollutants Load Reduction Potential Increase in Impervious Impervious N P TSS Bacteria Acreage Acreage Controlled by Controlled (billion (lbs/yr) (lbs/yr) (tons/yr) Stormwater cfu/yr) Projects 32% (proposed 2,217 371 75 61,062 11% projects) * Current Stormwater Control Levels are at 21% of impervious surface.

Using the distribution of projects included in the provisional inventory, several future control levels were evaluated using the WTM to estimate potential pollution reduction. Table 3-2 identifies the maximum control level evaluated (as percent impervious acres controlled) as well as the associated pollution reduction potential. The Plan Formulation appendix of the Anacostia Restoration Plan and Report provides the characteristics of each BMP type included in the provisional inventory.

To fully evaluate the benefits of providing different levels of stormwater control, the existing pollutant load and the pollution reduction potential in the watershed must be considered in terms of the existing Anacostia River TMDLs for nutrients and TSS (Kim et al., 2007; Mandel et al., 2008). The TSS TMDL calls for an 85-percent reduction in existing TSS loading to the Anacostia River watershed. The nutrient TMDL established a necessary reduction of 79-percent for nitrogen and 80-percent for phosphorus. Table 3-3 summarizes the overall Anacostia River TMDL reduction goals, the Sligo Creek existing pollutant loadings, and the ability of the various stormwater control levels to address the pollution reduction in the Sligo Creek subwatershed to help meet the Anacostia River TMDLs. The implementation of all of the proposed stormwater projects reduces the pollutant load between 4 and 9-percent. Given that the TMDL goals for the Anacostia River are between 79 and 85-percent reduction, stormwater controls alone will not be able to address the contribution from Sligo Creek.

Sligo Creek Subwatershed Plan 43

Table 3-3: Ability of Stormwater Control Levels to Address TMDL Goals in Sligo Creek Subwatershed Pollutant Reduction Impervious Control Level Achieved N P TSS

45,598 4,159 734 TMDL Reduction Goal for lbs/yr lbs/yr tons/yr Sligo Creek (79%) (80%) (85%)

Estimate of Existing Pollutant 57,718 5,198 864 Loads in Sligo Creek lbs/yr lbs/yr tons/yr 2,217 371 75 Maximum Reduction Potential lbs/yr lbs/yr tons/yr from Proposed Projects (4%) (7%) (9%)

It should be noted that the load reduction estimates of Table 3-3 do not account for reductions in stream channel erosion, which is another benefit of stormwater management. The following section addresses the potential reduction in stream channel erosion following the implementation of the proposed restoration actions.

Potential to Reduce Peak Flow Discharge

The TSS TMDL for the Anacostia River estimates that about 70 to 75-percent of the sediment delivered from the watershed to the tidal river comes from stream bank and channel erosion. Estimating the reduction of stream channel sediment loads that would result from controlling urban stormwater runoff is very challenging. A peak flow reduction analysis is used as a surrogate measure to give insight into the potential for reducing in-stream channel erosion loads. In fact, erosion of the stream channel is directly related to the increase in stream energy associated with the peak flow. Reducing the peak flow at the outlet of the watershed will lead to the reduction in erosive shear stress on the stream banks. Therefore, it is logical to assume potential reduction in stream bank erosion by quantifying the reduction in peak flows associated with the levels of stormwater control. Table 3-4 contains the results of that quantification. The CWP has an Impervious Cover Model (ICM) that classifies the ability of watersheds to support aquatic life based on the percentage of impervious surface. The ICM describes watersheds having an impervious surface cover between 0 to 10-percent as ‘sensitive’, 10 to 25-percent as being ‘impaired’, those having 25 to 60-percent impervious cover as ‘non-supporting’, and those with 60 to 100-percent impervious cover as ‘urban drainage’. With its approximately 34-percent impervious cover, Sligo Creek would be classified as ‘non-supporting’ by the ICM. The watersheds analyzed in preparation of the ICM were not segregated based on stormwater management, and a substantial number of those analyzed had minimal stormwater management. Recent studies of watersheds in nearby Montgomery County, Maryland, where stormwater management and other watershed restoration measures have been implemented strongly indicate

Sligo Creek Subwatershed Plan 44

that such watersheds can support much higher aquatic organism health than can watersheds lacking these management practices.

Accordingly, the expectation for the Sligo Creek subwatershed is generally that if stormwater management is improved and other watershed restoration measures implemented aquatic ecosystem health will also improve. This is an area of active ongoing investigation by scientists and engineers, and the relationship between watershed restoration and stream aquatic ecosystem health is impacted by many factors as was discussed earlier in this document. Although it is not possible to confidently predict the magnitude of aquatic ecosystem improvement that can be generated by watershed restoration measures, the effective resultant impervious cover that a combination of watershed restoration features installed within a given watershed would provide would be the maximum likely response.

The peak discharges are estimated using regression equations developed by the Maryland Hydrology Panel in support of the Maryland State Highway Administration (MSHA). The equations are used in the estimate of flood discharges for the design of culverts and bridges (Molgen, 2007). Details on the peak flow reduction potential analysis are given in the Plan Formulation appendix of the Anacostia Watershed Restoration Plan and Report.

Table 3-4: Peak Flow Analysis Results for Sligo Creek Subwatershed No Current Impervious Area Treated with Storm Water Controls Treatment Treatment 0% 22% 25% 30% 40% 50% 70% 100% Treated Treated Treated Treated Treated Treated Treated Treated Effective Percent 33.6* 27.7* 26.9 25.6 22.9 20.2 14.8 6.7 Impervious

Peak Flow 667 601 591 575 542 507 431 291 (cfs)

Peak Flow per square 59 53 52 51 48 45 38 26 mile (cfs)

Peak Flow in gpd per 38,132,696 34,254,795 33,608,478 32,962,161 31,023,210 29,084,260 24,560,042 16,804,239 square mile (cfs) = cubic feet per second (gpd) = gallons per day Conversion: 1 cfs = 646,316.883 gpd *These values were calculated in a slightly different manner than the method used for the cumulative analysis in this SWAP

Sligo Creek Subwatershed Plan 45

The Sligo Creek subwatershed spans both the piedmont and coastal plan geographic provinces, as such the peak discharges were estimated using a weighted average of the following two regression equations:

(Equation 1 – Coastal) Q1.25 = 18.62*DA0.611 * (IA+1)0.419 * (SD +1)0.165

(Equation 2 – Piedmont Urban) Q1.25 = 17.85 DA0.652 * (IA+1)0.635

The Q1.25 indicates that the peak discharges are associated with a rainfall event that has the likelihood of occurring once every 1.25 years. In addition, DA represents drainage area in square miles, IA represents-percentage of impervious area, and SD represents-percentage of group D soils, which are soils with a high runoff potential and slow infiltration rate. Although these regression equations have limitations, which are discussed in the Plan Formulation appendix of the Anacostia Watershed Restoration Plan and Report, they provide a reasonable initial measure of the potential for reducing peak discharges as a function of different amounts of stormwater management.

Among the limitations of this analysis, one is of particular importance. The peak discharge analysis should be interpreted with caution. Although the peak flow at the outlet of a watershed is used as a simple yardstick, reducing the peak flow is not a guarantee of reduced stream channel erosion throughout the watershed. Detailed hydrologic and hydraulic analyses are necessary to determine hydrograph timing to avoid inadvertently increasing channel erosion.

Potential to Reduce Pollutant Loads Using Street Sweeping

Street sweeping is included in the provisional project inventory as a trash control, but street sweeping can also serve as an effective pollutant removal technique if the right equipment and the right techniques are employed (Montgomery County 2002). Particles that accumulate on road surfaces such as road grit, sand, and dirt; heavy metals including copper, lead, and zinc; and nitrogen and phosphorus can all be removed to some extent by street sweeping. The highest concentration of pollutants is associated with the smallest particles of road grit (EPA, 1983). Of the three technologies available for street sweeping, regenerative air sweepers and vacuum assisted sweepers provide the greatest pollutant removal. Mechanical broom sweepers do the least to remove the small particles associated with most pollutants.

Decisions such as frequency of sweeping, type of road swept (residential or mixed use, etc.), whether cars are permitted to be parked in the roadway, and training of personnel performing the street sweeping affects the efficiency of the practice. Ideally, street sweeping is most effective when pollutants are permitted to accumulate and then the area is swept prior to a rain event. However, this situation is logistically difficult. The WTM is capable of estimating removal of N, P, and TSS by street sweeping. Evaluations with the WTM identify that weekly sweeping can remove 67-percent more N, P, and TSS than monthly sweeping.

Sligo Creek Subwatershed Plan 46

The benefit of street sweeping was evaluated for the roads within the Sligo Creek subwatershed. (Table 3-5). Information regarding the methodology and assumptions made in the analysis can be found in the Plan Formulation appendix to the Anacostia Watershed Restoration Plan and Report.

Table 3-5: Pollutant Reduction Estimate of Weekly Street Sweeping (Streets Only) Other Roads Annual Pollutant Reduction Percent Reduction Percent of N P TSS Roadway Miles N P TSS (lbs/yr) (lbs/yr) (tons/yr) Treated 5 6.6 232 26 3 0.4% 0.5% 0.4% 10 13.3 464 53 7 0.8% 1.0% 0.8% 15 19.9 696 79 10 1.2% 1.5% 1.2% 20 26.5 928 105 14 1.6% 2.0% 1.6% 25 33.2 1,160 132 17 2.0% 2.5% 2.0% 50 66.3 2,319 263 35 4.0% 5.1% 4.0% 75 99.5 3,479 395 52 6.0% 7.6% 6.0% 100 132.6 4,639 526 69 8.0% 10.1% 8.0%

Residential Roads Annual Pollutant Reduction Percent Reduction Percent of N P TSS Roadway Miles N P TSS (lbs/yr) (lbs/yr) (tons/yr) Treated 5 3.6 292 25 4 0.5% 0.5% 0.4% 10 7.1 585 51 8 1.0% 1.0% 0.9% 15 10.7 877 76 12 1.5% 1.5% 1.3% 20 14.3 1,169 101 15 2.0% 1.9% 1.8% 25 17.9 1,462 126 19 2.5% 2.4% 2.2% 50 35.7 2,924 253 39 5.1% 4.9% 4.5% 75 53.6 4,385 379 58 7.6% 7.3% 6.7% 100 71.4 5,847 505 77 10.1% 9.7% 9.0%

The benefits of street sweeping on pollutant removal can also be considered for parking lots. Parking lots accumulate trash and pollutants that eventually wash into the stormwater system during rain events. The results of the parking lot analysis are displayed in the Table 3-6. The benefit of sweeping parking lots does not appear to be great, but once accumulated over the entire watershed this practice has the potential to not only contribute to reaching trash reduction goals, but also pollutant removal goals if implemented on a large scale.

Sligo Creek Subwatershed Plan 47

Table 3-6: Pollutant Reduction Estimate of Weekly Sweeping of Parking Lots Parking Lots Annual Pollutant Reduction Percent Reduction Percent of N P TSS Parking Lots Acres N P TSS (lbs/yr) (lbs/yr) (tons/yr) Swept 5 6.1 7 1 0 0.04% 0.02% 0.04% 10 12.1 14 1 0 0.10% 0.04% 0.10% 15 18.1 21 2 0 0.10% 0.10% 0.10% 20 24.1 28 2 1 0.20% 0.10% 0.20% 25 30.2 36 3 1 0.20% 0.10% 0.20% 50 60.5 71 6 1 0.40% 0.20% 0.40% 75 90.7 107 9 2 0.60% 0.40% 0.60% 100 120.9 142 12 3 0.80% 0.50% 0.80%

The benefits of street sweeping on pollutant removal can also be considered for parking lots. Parking lots accumulate trash and pollutants that eventually wash into the stormwater system during rain events. The results of the parking lot analysis are displayed in the Table 3-6. The benefit of sweeping parking lots does not appear to be great, but once accumulated over the entire watershed this practice has the potential to not only contribute to reaching trash reduction goals, but also pollutant removal goals if implemented on a large scale.

Table 3-7: Total Pollutant Reduction Estimate of Weekly Sweeping of All Streets and Parking Lots Streets and Parking Lots Total Annual Pollutant Reduction Total-percent Reduction Percent N P TSS Swept Acres (lbs/yr) (lbs/yr) (tons/yr) N P TSS 5 58.9 549 54 8 1.0% 1.0% 0.9% 10 117.9 1,098 108 15 1.9% 2.1% 1.8% 15 176.8 1,647 162 23 2.9% 3.1% 2.7% 20 235.7 2,196 216 31 3.8% 4.2% 3.6% 25 294.6 2,745 270 39 4.8% 5.2% 4.5% 50 589.3 5,490 541 77 9.5% 10.4% 8.9% 75 883.9 8,235 811 116 14.3% 15.6% 13.4% 100 1178.5 10,980 1,082 154 19.0% 20.8% 17.9% Sligo Creek Subwatershed TMDL Reduction Goals 45,598 4,159 734 79% 80% 85%

As discussed previously, sweeping may be logistically difficult. Stormwater retrofits to the road network within the Sligo Creek subwatershed, including green streets, bioswales, or pervious pavement, in conjunction with street sweeping would increase the amount of pollutants removed from the system. These green streets initiatives would require programmatic or policy changes

Sligo Creek Subwatershed Plan 48 to local ordinances. These road network stormwater retrofits are further described in the Anacostia Watershed Restoration Plan and Report and associated Plan Formulation appendix.

Pollutant Reduction of Homeowner Stormwater Management

Provisional stormwater restoration projects implemented by governmental agencies alone are only one piece of the strategy needed to control stormwater and the pollutants carried into the Anacostia River watershed. Implementing every stormwater project outlined in this inventory will account for an approximate 11-percent increase in the impervious acres controlled by stormwater management within the Sligo Creek subwatershed. However, with approximately 18,700 residential homes in the subwatershed, there is also the need to involve private homeowners in the stormwater control effort. Homeowner efforts would target stormwater from the roofs, driveways, and sidewalks. A number of stormwater control treatments, or homeowner BMPs, are available for application: green roofs, rain gardens, rain barrels, permeable pavement, and downspout disconnects. Additional information on homeowner BMPs can be found in the Plan Formulation appendix to the Anacostia Watershed Restoration Plan and Report.

Table 3-8 summarizes the number of residential homes throughout Sligo Creek subwatershed and the related impervious acreage. The impervious acreage that is occupied by single family homes, multi-family homes, single family driveways, and sidewalks equals approximately 1,024 acres of the 2,375 total impervious acres, or 43-percent within the subwatershed. Stormwater management controls ion this acreage could contribute significantly to reducing pollutant and stormwater inputs throughout the watershed.

Table 3-8 : Sligo Creek Subwatershed Impervious Acres Analysis of Residential Homes Impervious acres

Number of Single Private Single Watershed Residential Family (multi- Family Sidewalks Area Homes Homes family) Driveway

UPPER 7,000 216.1 52.9 98.0 36.1 MIDDLE 7,501 207.4 59.5 105.0 35.4 LOWER 4,176 104.1 34.1 58.5 17.0 Total 18,677 527.6 146.5 261.5 88.5

Sligo Creek Subwatershed Plan 49

An evaluation was performed, using the WTM, to investigate the potential of the homeowner BMPs to control the stormwater inputs produced by residential homes within the subwatershed. Four of the practices are focused on rooftop runoff: green roofs, rain barrels, rain gardens, and downspout disconnects. The fifth practice directly applies to sidewalks and driveways. Six scenarios of various combinations of the five BMPs were evaluated.

1. Control 1-percent of the impervious acreage with green roofs, 1-percent with downspout disconnections, 1-percent with rain barrels and 1-percent with rain gardens. Control 1-percent of the sidewalk and drive way impervious acreage with permeable pavement.

2. Control 5-percent of the impervious acreage with green roofs, 5-percent with downspout disconnections, 5-percent with rain barrels, and 5-percent with rain gardens. Control 5-percent of the sidewalk and drive way impervious acreage with permeable pavement.

3. Control 10-percent of the impervious acreage with green roofs, 10-percent with downspout disconnections, 10-percent with rain barrels, and 10-percent with rain gardens. Control 10-percent of the sidewalk and driveway impervious acreage with permeable pavement.

4. Control 10-percent of the impervious acres with green roofs, 50-percent with downspout disconnections, 25-percent with rain barrels, and 15-percent with rain gardens. Control 50-percent of the sidewalk and driveway impervious acreage with permeable pavement.

5. Control half of the acreage of private, multi-family residences by treating 25-percent of the impervious acreage with rain gardens and 25-percent with green roofs. Control half of the single-family driveways and sidewalks with permeable pavement, and control all of the single-family home impervious roof acreage by treating 25-percent with rain barrels, 25-percent with green roofs, and 50-percent with rain gardens.

6. Control half of the acreage of private, multi-family residences by treating 30-percent of the impervious acreage with rain gardens, 15-percent with downspout disconnections, and 5-percent with green roofs. Control half of the single-family driveways and sidewalks with permeable pavement, and control all of the single- family home impervious roof acreage by treating 10-percent with rain barrels, 5- percent with green roofs, 15-percent with downspout disconnections and 20-percent with rain gardens.

Figure 3-1 illustrates the 6 scenarios of homeowner BMPs were analyzed.

Sligo Creek Subwatershed Plan 50

Figure 3-1: Homeowner BMP Scenarios

100% 100%

80% 80%

60% 60%

40% 40%

20% 20%

0% 0% Green Roof Disconnects Green Roof Rain Barrels Disconnects Rain Gardens Rain Barrels P. Pav ement Rain Gardens Scenario 1 Scenario 4 P. Pavement

100% 100%

80% 80%

60% 60%

40% 40%

20% 20%

0% 0%

Green Roof Green Roof Disconnects Disconnects Rain Barrels Rain Barrels Rain Gardens Rain Gardens P. Pavement Scenario 2 P. Pav ement Scenario 5

100% 100%

80% 80%

60% 60%

40% 40%

20% 20%

0% 0% Green Roof Green Roof Disconnects Disconnects Rain Barrels Rain Barrels Rain Rain Gardens Gardens P. Scenario 3 P. Pav ement Scenario 6 Pavement

Single Multi- Family Family

Sligo Creek Subwatershed Plan 51

The efficiencies used by the WTM for pollutant reduction estimates when evaluating the first four scenarios of homeowner BMPs are presented in Table 3-9 and Figure 3-2.

Figure 3-2: Removal Efficiencies of Homeowner BMPs in WTM

Table 3-9: Removal Efficiencies of Homeowner BMPs in WTM Pollutant Removal Efficiencies of WTM N P TSS Bacteria Green Roof 45% 45% 80% 0% Rooftop Disconnect 25% 25% 85% 0% Rain Barrel 40% 40% 40% 0% Rain Garden 64% 55% 85% 90% Permeable Pavement 59% 59% 75% 0%

Based on the removal efficiencies, rain gardens provide the greatest pollutant removal capability for treating rooftop run-off; however, implementation of this may be problematic in areas where there are large numbers of apartments or townhouses rather than single homes. For treating sidewalks and driveways, permeable pavement provides similar capabilities to rain gardens, except there is no reduction for bacteria. Plans that incorporate these two practices on residential properties would make the greatest pollutant removal contributions.

These scenarios evaluate potential plans that could be set as targets for homeowner participation in stormwater control programs. Tables 3-10 and 3-11 provide an estimate of the potential for each of these scenarios to reduce the current pollutant loadings to Sligo Creek.

Sligo Creek Subwatershed Plan 52

Table 3-10: Pollutant Reduction of Homeowner Stormwater Control Scenarios (Estimates made using WTM)

N P TSS Bacteria Scenario (lbs/yr) (lbs/yr) (tons/yr) (billions cfu/yr)

1 388 36 9 4,564 2 1,941 182 43 22,818 3 3,883 363 87 45,635 4 9,878 942 246 68,453 5 11,960 1,096 226 203,400 6 7,365 684 155 101,182

Table 3-11:-percent Reduction of Pollutants Estimated for Homeowner Scenarios and Acreage Controlled

Percent of Impervious Acreage Residential Scenario N P TSS Controlled Impervious Acreage Controlled

1 1% 1% 1% 58.0 5.7% 2 3% 3% 5% 152.3 14.9% 3 7% 7% 10% 304.6 29.7% 4 17% 18% 28% 849.1 82.9% 5 21% 21% 26% 775.8 75.8% 6 13% 13% 18% 512.0 50.0%

A significant fraction of pollutants could be controlled if homeowner stormwater controls were implemented over a large portion of the subwatershed. In order to achieve this, an effort needs to be put forth to increase public awareness and participation, so that all the citizens of the subwatershed are working together toward the common goal. Local governments can encourage this through significant outreach, coordination, technical assistance, and funding to extensively apply a homeowner’s stormwater management control program. If implemented, such programs have the potential to greatly reduce the pollutant loads to the subwatershed, particularly when implemented alongside provisional stormwater management projects implemented by local governments.

Sligo Creek Subwatershed Plan 53

Table 3-12 and Figure 3-3 presents a summary of the potential pollutant load reductions that could be achievable by implementing the aforementioned projects, and compares them to the TMDL reductions goals that were established for the Anacostia River. The numbers presented here, however, do not necessarily account for the interactions of the projects with one another and are clearly subject to some double-counting of reductions. Therefore the numbers in Table 3- 12 should not be considered in any further calculations, but rather taken in more relative terms of what is achievable. This double counting of reductions is likely attributed to double coverage of residential acreage through homeowner BMPs, green streets in residential areas, and sweeping of residential streets, because all three of these potential project types were considered independently when in reality they would affect the same physical acreage on a map. Likewise, the combining of stormwater retrofit projects with other practices would lead to same reductions being accounted for in multiple projects. The Plan Formulation appendix to the Anacostia Watershed Restoration Plan and Report addresses this occurrence in more detail.

Therefore, when considering the results of this analysis, it should be viewed not from the standpoint of whether or not a certain level of reductions can be achieved in 10 years, but rather what significant contributions can be made toward creating a healthier Anacostia River watershed. The data presented in this report is an encouraging indicator that it is not too late to take the steps necessary to improve the environmental conditions in the Anacostia River. The projects recommended in this report are a great start down that path, but they need to be supplemented with increased community involvement, a strong education effort, and more environmentally friendly policies. The goal should be to look back in 10 years and see the progress that has been made in restoring the Anacostia River and its subwatersheds.

Sligo Creek Subwatershed Plan 54

Table 3-12: Maximum Potential Pollutant Reduction for Stormwater Controls, Homeowner BMPs, and Street Sweeping TSS N (lbs/yr) P (lbs/yr) (tons/yr) Current Sligo Creek Loading 57,718 5,198 864 45,598 4,159 734 Sligo Creek Reduction Goals (79%) (80%) (85%) Maximum Possible Reduction Stormwater Controls (32% of Impervious Acreage Controlled) 2,217 371 75 LID ‘Green Street’ 10,536 886 195 Homeowner BMPs (Scenario 5) 11,960 1,096 226 Street Sweeping (75% of residential roads and 50% of lots) 7,036 641 99 Total Maximum Possible Reduction 31,749 2,995 595

% Total Reduction in Sligo Creek Loading 55% 58% 69%

Figure 3-3: Maximum Potential Reduction versus Anacostia River TMDL Goals

100%

80%

60% Maximum Potential Reduction 40% Anacostia TMDL Goal 20%

0% N P TSS

Sligo Creek Subwatershed Plan 55

Sligo Creek Subwatershed Plan 56

Section 4 10-Year Targets and Milestones

Sligo Creek Subwatershed Plan 57

Sligo Creek 10-Year Targets and Milestones

Sligo Creek 2020 Targets were determined based on implementation of the recommended projects within the Sligo Creek subwatershed along with realistic expectations of what can be accomplished in ten years. These targets are established to ensure that restoration of the subwatershed is proceeding in the right direction and at a continuous, reasonable pace.

Stormwater Management Using LID, ESD and other stormwater management techniques, stormwater retrofit projects should be implemented to increase control to a total of approximately 753 acres of existing impervious surfaces. This represents an 11-percent increase of controlled impervious surfaces.

Operate and maintain existing stormwater management facilities, stormwater drainage systems, and water and wastewater systems.

Aquatic Community Increase the general Index of Biotic Integrity (IBI) scores to “Fair Range” for both fish and macroinvertebrate communities.

Remove or modify fish passage barriers to open approximately 11.8 miles of Sligo Creek and tributaries for the movement of both residents and migratory fish.

Trash Reduction Using the MWCOG Trash Index for reference, reduce trash levels one tier from High to Medium or from Medium to Light. Implement at least the top 15 trash reduction projects from the recommended list by 2020.

Increase existing street sweeping programs to sweep approximately 50 additional curb miles weekly of residential and other roads. Additionally, increase sweeping of parking lots up to a total of approximately 190 acres.

Wetland Creation and Restoration Create or restore approximately 1.8 acres of permanent wetlands, and approximately 1.5 acres of vernal pools.

Riparian Corridors Create, restore, or treat approximately 11.3 acres of riparian, upland forest, and meadows. Additionally, manage invasive species for 4.6 acres.

Based on the Anacostia Watershed Forest Management and Protection Strategy and the Center for Watershed Protection recommended tree canopy cover as a-percentage of land area, increase the overall tree canopy over 40-percent.

Sligo Creek Subwatershed Plan 58

Environmental Restoration Programs Consider the implementation or expansion of programs designed to assist private property owners in controlling impervious surfaces with measures such as rain barrels and rain gardens.

Outreach and Public Participation Increase both the outreach and education programs for schools and private businesses on the restoration and protection of Sligo Creek subwatershed.

Establish a Friends of Sligo Creek organization, and launch a membership drive.

Promote homeowners and private business restoration incentives, such as reusable grocery bags (Washington DC already has a bag tax), rain gardens, rain barrels, and tree planting.

Expand existing programs to provide homeowners with access to BMPs such as rain barrels.

Promote passive use of existing parkland and employ more eco-friendly techniques in areas designated for high usage such as non-paved walking paths and increase height of grass mowing.

Sligo Creek Subwatershed Plan 59

Appendix 3

Sligo Creek Environmental

Baseline Conditions and Restoration Report

Prepared for:

Anacostia Watershed Restoration Partnership

Prepared by:

Metropolitan Washington Council of Governments

November 30, 2009 Table of Contents

1.0 General Environmental Conditions...... 1 2.0 Biological Community...... 9 3.0 Fish Passage...... 12 4.0 Water Quality Conditions ...... 25 5.0 Trash...... 29 6.0 Provisional Fish Species List...... 30 7.0 Restoration Projects...... 33

List of Figures

Figure 1. Sligo Creek North of Forest Glen Rd...... 1 Figure 2. Anacostia Watershed - Sligo Creek...... 1 Figure 3. Sligo Creek: Major Tributaries, 20081...... 2 Figure 4. Sligo Creek: Summary Vital Statistics...... 3 Figure 5. Sligo Creek: General Land Use/Land Cover, 20021...... 4 Figure 6. Sligo Creek: Impervious Features1...... 5 Figure 7. Sligo Creek: Hydrologic Soil Groups1...... 8 Figure 8. Anacostia Watershed: General Macroinvertebrate Community Health1...... 10 Figure 9. Anacostia Watershed: General Fish Community Health1...... 11 Figure 10. Sligo Creek: Existing Fish Barriers (2008)1...... 12 Figure 11. Sligo Creek: Forest Cover - 1936 versus 20001...... 13 Figure 12. Sligo Creek: Forest Patch Size, 20001...... 14 Figure 13. Sligo Creek Mature Forest Areas, 20001...... 15 Figure 14. Sligo Creek: Public Lands, 20051...... 16 Figure 15. Sligo Creek: Estimated Historical Wetland Areas1...... 17 Figure 16. Sligo Creek: NWI Wetland Areas, 20041...... 18 Figure 17. Sligo Creek: Major Invasive Plant Problem Areas, 20071...... 19 Figure 18. Sligo Creek: Major Roads and Storm Drain Outfalls1...... 20 Figure 19. Sligo Creek: General Level of Stormwater Management Control, 20081...... 21 Figure 20. Sligo Creek: Moderate-Severe Stream Channel Erosion Areas, 20071...... 23

-- Figure 21. Sligo Creek: General Sanitary Sewer Network1...... 24 Figure 22. Sligo Creek: Estimated Total Suspended Solids Load ...... 25 Figure 23. Sligo Creek: Estimated Phosphorus Load...... 25 Figure 24. Sligo Creek: Estimated Nitrogen Load...... 25 Figure 25. Sligo Creek: Stream Monitoring Stations, 2000-7*...... 27 Figure 26. Sligo Creek: COG Trash Survey Results, 2003-71...... 28 Figure 27. 2003 Sligo Creek Downstream Trash Trend...... 29 Figure 28. Sligo Creek: Select Restoration Projects1...... 33

List of Tables

Table 1. Sligo Creek: Acres of Impervious Surfaces, 2000 ...... 6 Table 2. Sligo Creek: General Stream Characteristics ...... 7 Table 3. Sligo Creek: Summary, Stormwater Management BMPs, 2006...... 22 Table 4. Sligo Creek: Provisional List of Resident and Migratory Fishes Collected or Expected (1898 -2006)...... 30 Table 4. Sligo Creek: Provisional List of Resident and Migratory Fishes Collected or Expected (1898 -2006)...... 31 Table 6. Confirmed, Expected and/or Possible Amphibian Species*...... 34 Table 7. Anacostia Tributaries: General Problem Category Summary, 2007...... 35

-ii- Sligo Creek

1.0 General Environmental Conditions Sligo Creek (Figure 1) is a free-flowing tributary of the Northwest Branch of the Anacostia River; the stream joins the Northwest Branch at the western city limits of Hyattsville (Figure 2). The subwatershed is gener- ally bound by Arcola Avenue and University Boule- vard to the north and east, Queen’s Chapel Road to the southeast, and the District of Columbia and Georgia Avenue to the west. Seventy-five percent of the subwa- tershed is in Montgomery County, with 20 percent and 5 percent in Prince George’s County and the District of Columbia, respectively. Major Sligo Creek tributaries (Figure 3) include: Wheaton Branch, Flora Lane tribu- Figure 1. Sligo Creek North of Forest Glen Rd. tary, Woodside Park tributary, Long Branch and Takoma Branch. Summary subwatershed information is provided in Figures 4-28 and Tables 1-7.

Dominant Land Uses: As seen in Figure 5, the three largest land uses by area in the Sligo Creek subwatershed are: 1) medium den- sity, single family residential, 2) forest cover, and 3) commercial. There are approximately 17,791 single family homes in the subwa- tershed.

Physical Characteristics: Based on USGS 7.5 minute digital elevation model (DEM) data, the Sligo Creek subwatershed is ap- proximately 7,085 acres (11.1 mi2) in size and approximately 34 percent impervious (Figure 6 and Table 1). Elevations range from 450 feet at the subwatershed divide to 35 feet at the confluence with the Northwest Branch. With an average gradient of 0.72 percent over 8.3 miles of the main stem, Sligo Creek flows from its headwa- ters in the Piedmont physiographic province into the Coastal Plain. Average baseflow for the lower Sligo Creek main stem is estimated Figure 2. Anacostia Watershed to be approximately 5-6 cubic feet per second (Table 2). The Fall - Sligo Creek Line or Zone represents the transitional area between the Piedmont Plateau and the Coastal Plain. It is characterized by an abrupt change in valley slope, with a corresponding increase in stream gradient, a boulder-strewn appearance, and small to medium-sized cataracts which act as barrier to the upstream migration of anadromous fish species such as Alewife and blueback herring. The entire lower main stem channel, from Riggs Road to the confluence with Northwest Branch, has been channelized. In addition, major portions of the Sligo Creek main stem (from University Boulevard downstream to Maple Avenue) has been armored with rip-rap (i.e., large stone), so as to reduce streambank erosion problems. Hydrologic soil groups for the subwatershed are depicted in Figure 7.

Biological Characteristics: Sligo Creek is designated a Use I stream (i.e., suitable for water recreation and support of aquatic life) by the Maryland Department of the Environment (MDE). The condition of fish and macroinvertebrate populations in Sligo Creek has improved since the completion of the first two phases of habitat restoration in the upper third of the subwatershed. These efforts, which have included

-- Appendix 3- Sligo Creek Figure 3. Sligo Creek: Major Tributaries, 20081

cola Ar Av e Colt Terrace Trb.

U nver sty

G

e o Upper (,0 Acres) r Blvd g  a Breewood A v Local Park e 822 Acres Trb.

W h e a to n Northwest Branch Subwatershed Br an ch

¨¦§495 Slgo GC Flora Lane Trb. Trb. 227 Acres Bennngton Mddle (,0 Acres) Woodsde Park Branch Trb. d R 799 Acres L e l o l 208 Acres  n v g s e l Greenbrer o C Drve Trb. Rd

Rock Creek Watershed B r a h c n n c a h r B y e n P Parksde Road

Trb. . .

o o

C C

y s ' r

e e

g r Lower m

o o

g e t

Maple Avenue n G

o e (, Acres)

c Trb. M n  r e P v Legend A

M Streams D o s n t tg r o 806 Acres ct m o f e h Open C ry c o C an lu o r m . B b a Pped a m ko Ta Rd Subwatershed Unt e r s h g s g p R Cty of Takoma Park m a Rollngcrest H w Trb. e Raydale Road N ± Trb. 0 0.  Mles Source: USGS 000, MCDEP 00, PGDER 00 and MWCOG 00

-- Appendix 3- Sligo Creek controlling stormwater quantity and quality, restoring both tributary and main stem instream habitat, cre- ating wetlands, reforestation, and native fish and amphibian reintroduction have resulted in aquatic habi- tat rankings of greater than 70% (partially supporting) of reference conditions at three main stem sam- pling sites. Although aquatic biota are correspondingly healthier and more diverse than during previous sampling, main stem populations remain impacted, scoring no better than 36% (moderately impaired) of reference conditions. Several physical barriers to both resident and anadromous fish movement and mi- gration are present downstream of Riggs Road. These, as well as other barriers in Sligo Creek, have been identified and remain as a restoration challenge for this subwatershed.

Condition Summary: Sligo Creek is one of the most urbanized subwatersheds within the Maryland por- tion of the Anacostia watershed. Approximately 90 percent of the total subwatershed area is developed, and only 15 percent of the subwatershed remains forested (Figures 11-13). The majority of the stream is bordered by a narrow buffer of parkland (Figure 14) owned and maintained by the Maryland-National Capital Park and Planning Commission (M-NCPPC). However, only about 35 percent of the stream miles have an adequate riparian forest buffer (i.e., 300-foot total width). Initial indications are that com- prehensive stream restoration efforts in the subwatershed, as well as fish re-introduction, have been suc- cessful in partially restoring the aquatic ecosystem of Sligo Creek. The impaired condition of the aquatic biota that remains following these efforts are attributable to how recently these projects were completed and the need for additional stormwater management controls and instream restoration work. Planned fu- ture projects include, but are not limited to: stormwater management focusing on the employment of low impact development (LID) and environmentally sensitive design (ESD), wetland creation, aquatic and terrestrial habitat restoration, fish barrier modification/removal, invasive plant management, trash reduc- tion and potentially additional fish reintroductions. Figures 15-17 illustrate historical and current wetland conditions and invasive plant problem/ current management areas in the subwatershed.

Figure 4. Sligo Creek: Summary Vital Statistics

Size/Population Impervious Level (34%) • Total Area: ~7,085 acres (11.1 mi2) • Roads: ~204.0 mi/795.2 acres • No. of Single Family Homes: 18,677 • Parking Lots: ~383.3 acres • Population: ~ 81,943 • Roofs: ~846.7 acres • Population Density: ~7,081/mi2 • Single Family Driveways: ~261.5 acres • Sidewalks: ~88.5 acres

Forest Cover (14.9%) Wetland Cover (0.02%)

• 1936/38: 3.9 mi2; 35.1% • Palustrine: none • 2000: 1.7 mi2; 14.9% • Riverine: ~1.5 acres • Lacustrine: none

Stormwater Management • Total Area Controlled: ~1,505 acres (2.4 mi2; 21%) • # of BMPs: 87

-- Appendix 3- Sligo Creek Figure 5. Sligo Creek: General Land Use/Land Cover, 20021

Land Use/Land Cover Acreage & Percent Area of Watershed cola Ar Av e Colt Terrace Trb.

U Upper nver sty

G

e

o r Blvd g  a Breewood A v Local Park e Trb.

W h e a to n macroinvertebrate Br an ch

¨¦§495 Slgo GC Flora Lane Trb. Trb.

Bennngton Woodsde Park Branch Trb. d R Mddle

L e l o l  n v g s e l Greenbrer o C Drve Trb. Rd

Legend Parksde Road Streams Trb. B r a h Open c n n c a h r Pped B y e n Subwatershed Unt P

. .

o o Cty of Takoma Park C C y s ' r

e e

g m r

o o

g e t

Low-densty resdental G Maple Avenue n o e

c Trb. M n  r e P Medum-densty resdental v A Lower

M Hgh-densty resdental D o s n t tg r o ct m o f e h C ry c Open Space, Forest Cover, o C an lu o r m . B b a Insttutonal and Water  m a ko Commercal Ta Rd

e r s h g s g Industral p R m a Rollngcrest H w Trb. e Raydale Road N ± Trb.

0 0.   Mles Source: Maryland Dept. of Plannng 00 and DC Offce of Plannng 00

-- Appendix 3- Sligo Creek Figure 6. Sligo Creek: Impervious Features1

Arcola Av e Colt Terrace Trb.

U Upper nver sty

G

e

o r Blvd g  a Breewood A v Local Park e Trb.

W h e a to n

Br an ch

¨¦§495 Slgo GC Flora Lane Trb. Trb.

Bennngton Woodsde Park Branch Trb. d Mddle R

L e l o l  n

v g s e l Greenbrer o C Drve Trb. Rd

B r a h c n n c a h r B y e n Parksde Road P Trb. . . Legend o o C C

y s ' r

e e

g m r Streams o o g e t

Maple Avenue G n

o e

c Trb. M n  Open r e P v Lower Pped A M D o s n t tg r o Subwatershed Unt ct m o f e h C ry c o C an lu o r m . B Buldngs b a  m a ko Ta Rd Roads, Parkng Lots & Sdewalks e r s h g s g Cty of Takoma Park p R m a H Rollngcrest w Trb. e Raydale Road N ± Trb. 0 0.   Mles Source: M-NCPPC 00 and MWCOG 00

-- Appendix 3- Sligo Creek

Road

Raydale 65

5.6 7.3 0.2 1.3 0.9 0.8 0.9 2.9 1.4 211 18.9 29%

Park Minor Tributaries Breewood

51 45

1.6 3.2 3.3 1.5 1.3 0.3 0.7 0.3 4.8 14.7 33%

Branch Takoma Takoma

806

59.6 16.1 39.6 29.3 20.0 30.7 10.8 55.7 37% 108.9 298.0

Branch Long

9.6 799

61.5 91.5 23.0 11.7 16.8 13.2 32.8 34.7 31% 250.7 2,346 2,196

Park Woodside 3.6 6.1 2.2 6.4 3.4 2.3 5.8 438 208 16.7 26.5 60.9 29%

Major Tributaries Flora Lane Flora 7.3 0.6 4.9 2.6 3.2 524 227 11.1 16.2 23.7 10.5 83.8 37%

Acres / Miles Acres / Miles Acres / Miles Acres / Miles Acres / Miles Acres / Miles

Branch Wheaton 822 71.5 54.6 26.7 42.0 29.5 31.3 28.4 11.0 40% 114.3 328.8 1,906 58.5 49.4 53.7 43.5 34.1 17.0 35% 1,525 Lower Acres / Miles Acres / Miles 66.7 66.4 71.0 59.5 35.4 34% 105.0 Acres / Miles Subwatershed Units 89.5 57.6 58.1 52.9 98.0 36.1 32% 147.1 133.1 103.1 327.1216.1 337.9 207.4 181.7 104.1 2,950 2,610 Upper Middle Acres / Miles Driveway area equals the number of single family houses multiplied by an average driveway area of 0.014 acres. Sidewalk width equal to 4ft, running the length of one side all local roads. 88.5 34% 383.3 205.6 177.7 846.7 172.6 146.5 527.6 261.5 7,085 18,677 7,000 7,501 4,176 2,375.2 956.1 882.3 536.7 186.8 21.5 88.1 7.9 58.8 8.4 39.9 5.2 24.8 2.7 18.5 1.5 4.3 0.5 26.5 2.8 12.1 1.4 3.3 0.4 0.0 0.0 608.4 182.6 259.7 74.5 212.1 73.1 136.6 35.0 80.5 22.7 20.0 6.5 15.8 4.8 55.6 19.7 79.8 22.2 2.3 0.7 6.4 1.8 795.2 204.0 347.8 82.4 270.9 81.4 176.5 40.2 105.3 25.4 38.5 8.0 20.1 5.3 82.1 22.5 91.9 23.6 5.6 1.1 6.4 1.8 Acres / Miles Subwatershed Category Table 1. Sligo Creek: Acres of Impervious Surfaces, 2000 Acres 1. Sligo Creek: Table 1. Roads a. State/Fed b. Local 2. Parking Lots a. Public/Institutional b. Private 3.Roofs a. Public/Institutional b .Private c. Single Family 3. Other a. Sidewalks * b. Single Family Driveways ^ Total Avg. % Imperviousness # of Single Family Homes Total Drainage Area ^ Driveway area assumptions * Sidewalk area assumptions Note: Drainage Area and Tributary area calculated from the USGS digital Elevation Model (DEM)

-- Appendix 3- Sligo Creek (Partial/ Barriers Complete) No. of Fish 000 / / / 000 / 0 0/ / 0/0 Altered Stream Approx. % Channel Area Stream Channel Total Open Length (mi) 3 (cfs) Mean Approx. Baseflow (%) Mean Stream Gradient ) 2 Area (ac/mi /./0.0/0. ./. .0/. . 0.-0.0 . 0.-0.0 . 0.0-0.0 .0 0.-0.0 0. 0.-.0 0. . 00 . / /<0./<0. . . 0.0-0. 0.0-0. <0. <0. 0 0 0/ 0/0 Drainage ,0/.,0/. 0.,/. 0. 0. .0-.0 .0-.0 .0-.0 . . . Province Pedmont Pedmont Pedmont Pedmont Pedmont Pedmont Pedmont Pedmont/ Coastal Plan Coastal Plan Coastal Plan Physiographic 1 I I I I I I I I Use MDE Class Areas Mainstem Tributaries Minor Tributaries Mainstem/Tributary MDE Use I = Water contact recreaton and protecton of nontdal warmwater aquatc lfe Dranage Area (D.A.) Calculated from USGS Dgtal Elevaton Model (DEM) - 0 meter One cubc foot per second (cfs)= . gallons/mnute Upper Mddle Lower Wheaton BranchFlora Lane Woodsde Park Long Branch I Takoma Branch Breewood Local ParkRaydale Road I    Table 2. Sligo Creek: General Stream Characteristics General Stream 2. Sligo Creek: Table

-- Appendix 3- Sligo Creek Figure 7. Sligo Creek: Hydrologic Soil Groups1

cola Ar Av e Colt Terrace Trb.

U Upper nver sty

G

e

o r Blvd g  a Breewood A v Local Park e Trb.

W h e a to n

Br an ch

¨¦§495 Slgo GC Flora Lane Trb. Trb.

Bennngton Woodsde Park Branch Trb. d R Mddle

L e l o l  n v g s e l Greenbrer o C Drve Trb. Rd

Legend

Streams B r a h c n Open n c a h r B Pped y e n Parksde Road Subwatershed Unt P Trb. . .

o o

C C

y s ' r

e e

Cty of Takoma Park g m r

o o

g e t

Maple Avenue n G

o e

c 'A' Sols Trb. M n  r e P v Lower 'B' Sols A

M D o s n 'C' Sols t tg r o ct m o f e h C ry c o C an lu o r 'C/D' Sols m . B b a  m a ko 'D' Sols Ta Rd e r s h g s g p R m a Rollngcrest H w Trb. e Raydale Road N ± Trb. 0 0.   Mles Source: USDA, 00

-- Appendix 3- Sligo Creek 2.0 Biological Community

Aquatic Community

The health of fish and macroinvertebrate (i.e., animals without backbones that are larger than the size of a pencil dot) communities provide an extremely powerful indicator of overall stream health.

Since the late 1980’s many natural resources professionals working in the Anacostia watershed have monitored these communities using an Index of Biotic Integrity or IBI approach. The IBI compares the fish and macroinvertebrate communities of urban streams with those of healthy reference streams, in- corporating geographical, ecosystem, community, and population, as well as distribution and abundance variables that account for differences in water body size, type, and region of occurrence. While there are still many gaps in the Anacostia macroinvertebrate and fish community IBI databases, available data have proven extremely valuable in the restoration effort.

As previously indicated, Figures 8 and 9 depict, based on macroinvertebrate and fish community biologi- cal indicators, the general health of streams in both Sligo Creek and the Anacostia watershed. In general, the overall health of the macroinvertebrate and fish communities in Sligo Creek can be generally charac- terized as poor to good.

-- Appendix 3- Sligo Creek Figure 8. Anacostia Watershed: General Macroinvertebrate Community Health1 (1999-2007)

Paint Northwest Branch Little Branch Paint Branch Prince George's County

Indian Creek

Upper Beaverdam ¤£29 ¨¦§95 Creek

Montgomery County ¤£1

TS295

¨¦§495 Sligo Creek

Still Creek

Brier Ditch

District of Columbia Northeast Branch Hickey Run £50 ¤ Lower Beaverdam ¨¦§95 Creek 495 Potom ¨¦§ ac Tidal River

R Watts Branch

 v e r Stream Biological Conditions* ¨¦§395 Excellent Good Far Poor Pope Fort Dupont Branch Tributary No current data ± ¨¦§295 *Based on Macronvertebrate Communty Bologcal Indcators 0    Mles  Source: MWCOG, 00

-10- Appendix 3- Sligo Creek Figure 9. Anacostia Watershed: General Fish Community Health1 (1999-2007)

Paint Northwest Branch Little Branch Paint Branch Prince George's County

Indian Creek

Upper Beaverdam ¤£29 ¨¦§95 Creek

Montgomery County ¤£1

TS295

¨¦§495 Sligo Creek

Still Creek

Brier Ditch

District of Columbia Northeast Branch Hickey Run £50 ¤ Lower Beaverdam ¨¦§95 Creek 495 Potom ¨¦§ ac Tidal River Watts Branch

R

 v e r Stream Biological Conditions* ¨¦§395 Excellent Good Far Fort Dupont Poor Pope Tributary No current data Branch ± ¨¦§295 *Based on Fsh Communty Bologcal Indcators 0     Mles Source: MWCOG, 00

-11- Appendix 3- Sligo Creek 3.0 Fish Passage Decades of stream channel erosion can uncover utility lines, which were once buried 3-4 feet below the stream bed. When sufficiently exposed, these pipes often create barriers that prevent fish from mov- ing upstream. This problem is most acute for migratory fish species, such as river herring which cannot leap over even very small obstructions. Road culverts can also become fish barriers when the streambed downstream of a culvert erodes, creating a small drop that fish cannot get over. The restoration partners have been successful in beginning to remove fish barriers in theAnacostia. In many cases the actual utility line or structure that is causing the blockage cannot be removed. Rather these fish barriers are “modified” to allow fish passage. Fish barrier modification can be accomplished by gradually raising the streambed immediately downstream of the blockage, causing water to back up and pool over the barrier, eliminat- ing the difference in water elevation and allowing fish to move upstream. As a part of the mitigation for the Woodrow Wilson Bridge, four fish barriers were modified in lower Sligo Creek by Potomac Crossing Consultants in 2003 (Figure 10). A total of 57 fish barriers currently remain in the Sligo Creek subwater- shed.

Figure 10. Sligo Creek: Exist- ing Fish Barriers (2008)1

-12- Appendix 3- Sligo Creek Figure 11. Sligo Creek: Forest Cover - 1936 versus 20001

Arcola Av Colt e Terrace Trb. U nive G rs it e y o

r g

i Blvd Breewood a Local Park Trb.

A 000: ,0 total acres v  e W h e (. m ) a : , total acres to  n

(. m ) Br an ch

Arcola Av Colt e Terrace Trb. ¨¦§495 U Slgo GC nive G rs Trb. it e y o Flora Lane r g Trb. i Blvd Breewood a Local Park Woodsde Park Bennngton Trb. Trb. Branch d A R v L e e W l o l h i n e v g a s to e Greenbrer n l o Drve Rd C Br Trb. an ch

h B

c r n a a n r c ¨¦§495 B h Slgo GC y e . . n o i o Trb. C P C s Parksde Road ' y Flora Lane r e e g Trb. r

m o

o Trb. e g t G

n Bennngton e Maple Avenue o Woodsde Park c

M n Branch  Trb. Trb. r d P

R L e l o l M i n D o d v g s n R h s tr tg c c o e n e Greenbrer t m a l o r r f e i B o Rd C ry h a Drve o C s m C lu o o m . p k Trb. b a d a m T R a s g H ig w R e h B N Rollngcrest c r n a a n Raydale Road Trb. r c B h Trb. y

e . . n o i o C P C s ' Parksde Road y r e

e g Trb. r m o

o e

g t G

n e o Maple Avenue c

M n  Trb. r Legend P

Streams M D o d s n t t R h r g nc ct o e a Open o m r r f e i B C ry h a o C s m lu o o m . p k d Pped b Ta a m R a s g Subwatershed Unt H ig w R e Forest Cover N Rollngcrest Raydale Road Trb. ± Trb. 0 0.   Mles Source: MWCOG 00

-13- Appendix 3- Sligo Creek Figure 12. Sligo Creek: Forest Patch Size, 20001

Arcola A ve Colt Terrace Trb.

U Upper nver sty

G

e

o r Blvd g  a

A Breewood

v e Local Park Trb.

W h e a to n

Br an ch

¨¦§495 Slgo GC Trb. Flora Lane Trb.

Bennngton Woodsde Park Branch Trb. d R Mddle

L e l o l  n v g s e l Greenbrer o C Drve Trb. Rd

B

r a h n c c n h a Legend r B y e Streams nParksde Road P Trb. . . Open o o C C

y s ' r

e e

g Pped r m

o o

g e t Maple Avenue n G o Subwatershed Unt e

c Trb. M n  r e P v Lower Cty of Takoma Park A

M Patch Sze D o s n t tg r o ct m o f e - acres C ry o C ch lu o n m . ra b B - acres a a om d Tak R

e - acres r s h g s g p R m > acres a Rollngcrest H w Trb. e Raydale Road N ± Trb. 0 0.  Mles  Source: MWCOG 00

-14- Appendix 3- Sligo Creek Figure 13. Sligo Creek Mature Forest Areas, 20001

Arcola A ve Colt Terrace Trb.

U Upper nver sty

G

e

o r Blvd g  a

A Breewood

v e Local Park Trb.

W h e a to n

Br an ch

¨¦§495 Slgo GC Trb. Flora Lane Trb.

Bennngton Woodsde Park Branch Trb. d R Mddle

L e l o l  n v g s e l Greenbrer o C Drve Trb. Rd

B

r a h n c c n h a r B y e n Parksde Road P Trb. . .

o o

C C

y s ' Legend r e e

g m r

o o

g e Streams t Maple Avenue n G o e

c Trb. M n Open  r e P v Lower Pped A

M D o Subwatershed Unt s n t tg r o ct m o f e C ry Cty of Takoma Park o C ch lu o n m . ra b B a a om d Mature Forest (~0 acres)* Tak R

e * Mature unbroken woodland area greater than r s h g s g or equal to  years old, wth an area p R m a Rollngcrest greater than  acres. H w Trb. e Raydale Road N ± Trb. 0 0.  Mles  Source: MWCOG 00

-15- Appendix 3- Sligo Creek Figure 14. Sligo Creek: Public Lands, 20051

cola Ar Av e Colt Terrace Trb.

U Upper nver sty

G

e

o r Blvd g  a Breewood A v Local Park e Trb.

W h e a to n

Br an ch

¨¦§495 Slgo GC Flora Lane Trb. Trb.

Bennngton Woodsde Park Branch Trb. d R Mddle

L e l o l  n v g s e l Greenbrer o C Drve Trb. Rd

B r a h c n n c a h Legend r B y Streams e n P Parksde Road

Open Trb. . . o o

C C

y s ' r

e e Pped g m r

o o

g e t Subwatershed Unt Maple Avenue n G o e

c M Trb. n  r e P Cty of Takoma Park v A Lower

M D o Conservaton Easement (. acres; <0.%) s n t tg r o ct m o f e h C ry c o C an Park (. acres; .0%) lu o r m . B b a  m a ko Hstorcal Preservaton Area (. acres; <0.%) Ta Rd e r s h g s g Insttutonal* (. acres; .%) p R m a Rollngcrest *Schools, Lbrares, etc. H w Trb. e Raydale Road N ± Trb. 0 0.  Mles MWCOG 00, M-NCPPC 00 and DOI 00

-16- Appendix 3- Sligo Creek Figure 15. Sligo Creek: Estimated Historical Wetland Areas1

Estimated Wetland Acreages Category* Acreage Arcola A I. Floodplan/Dranageway Sols 0 ve Colt II. Streams (outsde Category I area)  Terrace Trb. Total Acres  Un vers ty *Note: For Category I, floodplan/dranageway sols shown are characterzed by Upper very slow nfltraton rates, hgh water tables and perodc floodng. For Category II, G e the surface area of hstorc and current stream channels has been estmated o r Blvd g  a

A Breewood

v e Local Park Trb.

W h e a to n

Br an ch

¨¦§495 Slgo GC Trb. Flora Lane Trb.

Bennngton Woodsde Park Branch Trb. d R Mddle

L e l o l  n v g s e l Greenbrer o C Drve Trb. Rd

B

r a h n c c n h a r Legend B y e n Parksde Road Streams P Trb. . .

o o Open C C

y s ' r

e e

g m r Pped o o g e t Maple Avenue n G o e

c Subwatershed Unt Trb. M n  r e P v Lower Cty of Takoma Park A

M D o Sol Types s n t tg r o ct m o f e C ry Bale o C ch lu o n m . ra b B a a om d Codorus Tak R

e r s h g Hatboro s g p R m a Rollngcrest Iuka H w Trb. e Raydale Road N ± Trb. 0 0.   Mles Source: MWCOG 000

-17- Appendix 3- Sligo Creek Figure 16. Sligo Creek: NWI Wetland Areas, 20041

Arcola A ve Colt Terrace Trb.

U nver sty Upper G

e

o r Blvd g  a

A Breewood

v e Local Park Trb.

W h e a to n

Br an ch

¨¦§495 Slgo GC Trb. Flora Lane Trb.

Bennngton Woodsde Park Branch Trb. d R Mddle

L e l o l  n v g s e l Greenbrer o C Drve Trb. Rd

B

r a h n c c n h a r B y Legend e n Parksde Road P Streams Trb. . .

o o

C C

y s ' Open r e e

g m r

o o

g e Pped t Maple Avenue n G o e

c Trb. M n  Subwatershed Unt r e P v Lower Cty of Takoma Park A M D o s n t tg Wetlands Classfcaton* r o ct m o f e C ry o C ch lu o n Palustrne ~ acres m . ra b B a a om d Rverne ~ acres Tak R e r s h g s g *The wetland layer s a combnaton of NWI p R m a Rollngcrest and Maryland DNR Data H w Trb. e Raydale Road N ± Trb. 0 0.   Mles Source: USFWS 00 and USFWS 00

-18- Appendix 3- Sligo Creek Figure 17. Sligo Creek: Major Invasive Plant Problem Areas, 20071

cola Ar Av e Colt Terrace Trb.

U Upper nver sty

G

e

o r Blvd g  a Breewood A v Local Park e Trb.

W h e a to n

Br an ch

¨¦§495 Slgo GC Flora Lane Trb. Trb.

Bennngton Woodsde Park Branch Trb. d R Mddle

L e l o l  n v g s e l Greenbrer o C Drve Trb. Rd

B r a h c n n c a h r B y e n P Parksde Road

Trb. . . o o

Legend C C

y s ' r

e e

g Streams m r o o

g e t Maple Avenue n G o Open e c Trb. M n  r e P Pped v A Lower Subwatershed Unt M D o s n t tg r o ct m o f e h Cty of Takoma Park C ry c o C an lu o r m . B b a  m Invasve Plant Management Area a ko Ta Rd

e r s Invasve Plant Problem Area h g s g p R m a Rollngcrest H w Trb. e Raydale Road N ± Trb. 0 0.   Mles Source: MWCOG 00 and M-NCPPC 00

-19- Appendix 3- Sligo Creek Figure 18. Sligo Creek: Major Roads and Storm Drain Outfalls1

cola Ar Av e Colt Terrace Trb.

U Upper nver sty

G

e

o r Blvd g  a Breewood A v Local Park e Trb.

W h e a to n

Br an ch

¨¦§495 Slgo GC Flora Lane Trb. Trb.

Bennngton Woodsde Park Branch Trb. d R Mddle

L e l o l  n v g s e l Greenbrer o C Drve Trb. Rd

B r a h c n n c a h r B y e n P Parksde Road

Trb. . .

o o

C C

y s ' r

e e

g m r

o o

g e t

Maple Avenue n G

o e

c Trb. M n  Legend r e P v Lower Streams A

M D o Open s n t tg r o ct m o f e h Pped C ry c o C an lu o r m . B b a  m Subwatershed Unt a ko Ta Rd

e Cty of Takoma Park r s h g s g ! p R Storm Dran Outfall (~ total) m a Rollngcrest H w Trb. e Raydale Road N ± Trb. 0 0.   Mles Source: MCDEP, PGDER and Cty of Takoma Park 00

-20- Appendix 3- Sligo Creek Figure 19. Sligo Creek: General Level of Stormwater Management Control, 20081

Arcola A ve Colt Terrace Trb.

U Upper nver sty (Area: 2,950 ac; # of BMPs: 44;

G e DA controlled: 1,425 ac, 49%) o ! r Blvd g  a

A Breewood

v e Local Park Trb.

W h e a to n

! Br an ch

! Mddle ! ¨¦§495 ! ! (Area: 2,610 ac; # of BMPs: 39; Slgo GC Trb. DA controlled: 76.4 ac, 3%) Flora Lane Trb.

Bennngton Woodsde Park Branch Trb. d R

L e l o l  n v g s e l Greenbrer o C Drve Trb. Rd

B

r a h n c c n h a r B y e n Parksde Road P Trb. Legend . .

o o

C C

y s ' Streams r e e

g m r

o o

g e Open t Maple Avenue n G o e

c Trb. M n  Pped r e P v Subwatershed Unt A

M D o s n Controlled Area (~,0 acres) t tg r o ct m o f e C ry o C ch lu o n m . ra Stormwater Flow Dverson Area (acres) b B a ! a om d ! Tak R

e Cty of Takoma Park r ! s h ! g s g p R ! m Exstng Stormwater BMP Ste ( total) a Rollngcrest H w Trb. e Raydale Road N Trb. ± Lower 0 0.  (Area: 1,525 ac; # of BMPs: 4;  Mles Source: MWCOG, PGDER and MCDEP 00 DA controlled: 3.6 ac, <1.0%)

-21- Appendix 3- Sligo Creek Table 3. Sligo Creek: Summary, Stormwater Management BMPs, 2008

No. of Percent of D.A. Controlled Type Facilities Total BMP's (ac.) 1. Dry Pond  .0% . 2. ED Dry Pond 3. Wet Pond 4. ED Wet Pond  .% ,0.0 5. Wetland (non-ED and ED)  .% . 6. Infiltration (Trench or Basin)  .% . 7. Oil Grit Separator  .% . Water Quality Inlet (e.g. 8. Stormceptor, Bay Saver, etc)  0.% . 9. Bioretention /Rain Garden  .0% . 10. 'Green Street'*  .% .0 11. Biofiltration Swale  .% . 12. Grass Swale w/ Check Dams 13. Porous Pavement 14. Sand Filter  .% . 15. Underground Pipe Storage  .% . 16. Cistern 17. Green Roof 18. Other  .% . Total 87 100.0% 1,505.0 May include a mix of LID techniques including, but not limited to: bioretention, * raingarden, biofiltration swale, soil ammendment, etc.

-22- Appendix 3- Sligo Creek Figure 20. Sligo Creek: Moderate-Severe Stream Channel Erosion Areas, 20071

Arcola A ve Colt Terrace Trb.

U Upper nver sty

G

e

o r Blvd g  a

A Breewood

v e Local Park Trb.

W h e a to n

Br an ch

¨¦§495 Slgo GC Trb. Flora Lane Trb.

Bennngton Woodsde Park Branch Trb. d R Mddle

L e l o l  n v g s e l Greenbrer o C Drve Trb. Rd

B

r a h n c c n h a r B y e n Parksde Road P Trb. . . Legend o o C C

y s ' r

e e

g Streams m r o o

g e t Maple Avenue n G o Open e c Trb. M n  r e P Pped v Lower A

Subwatershed Unt M D o s n t tg r o ct m o f e Cty of Takoma Park C ry o C ch lu o n m . ra b B Moderate-Severe Stream a a om d Channel Eroson Tak R

e (~. mles*) r s h g s g *Stable Stream Channel Length p R m a Rollngcrest (~0. mles) H w Trb. e Raydale Road N ± Trb. 0 0.   Mles Source: MWCOG 00

-23- Appendix 3- Sligo Creek Figure 21. Sligo Creek: General Sanitary Sewer Network1

Lttle Lttle P Lttle Pa

Pant Branch Pant Branch

Arcola A ve Colt Terrace Trb.

Unv ers Upper ty

G

e

o r Blvd g

 a Breewood Pant Branch A v Local Park e Trb.

W h e a to n

Br an ch Main Trunk Sewerlines ~30 miles Sewer Lnes >0"

¨¦§495 Slgo GC Flora Lane Trb. Trb.

Bennngton Mddle Woodsde Park Branch Trb. d R

L e ll o  v Greenbrer n s g le o Drve C Trb. Rd

B r a h c n n c a r h B y e n  . Parksde Road . P o o

C Trb. C s ' y

r e

e g r m o o e g t Maple Avenue G n

e o Trb. c M n Legend  r

e P v Streams A M D o Lower s n tr tg Open c o t m o f e ch C ry n o C ra Pped lu o m . B b a a om Rd Subwatershed Unt Tak e r s h g s g p R Sewer Lnes (~ mles) m a Rollngcrest H w e Raydale Road Trb. Cty of Takoma Park N ± Trb. 0 0.   Mles Source: DCWASA 00 and WSSC 00

-24- Appendix 3- Sligo Creek 4.0 Water Quality Conditions It is well known that uncontrolled storm- water runoff leads to accelerated stream- Slgo Creek  Northwest Branch  bank and streambed erosion and the Pant Branch  transport of sediment. The finer-grained Lttle Pant Branch  sediments released in this process, includ- Indan Creek  ing sand, silt, and clay, impair river and Beaverdam Creek  stream habitat. They also reduce water Stll Creek  clarity, bind with a myriad of pollutants, Brer Dtch  Northeast Branch  and at extremely high levels, can clog the Lower Beaverdam Creek  gills of many aquatic organisms. As seen Watts Branch  in both Figures 18-19 and Table 3, there Fort Dupont  are over 200 storm drain outfalls in Sligo Pope Branch  Creek and only about 21 percent of the Hckey Run  0 0 0 0 0 subwatershed has stormwater controls. Total Suspended Solids (tons/year/square mile) Figure 22. Sligo Creek: Estimated Total Suspended Solids Load The monitoring of Total Suspended Solids

(TSS) loads provides an indication of the Slgo Creek 0 severity of erosion in a watershed. The Northwest Branch 0 high level of imperviousness (i.e., surfaces Pant Branch  through which rainfall does not penetrate) Lttle Pant Branch  Indan Creek  in the Sligo Creek subwatershed along Beaverdam Creek  with an inadequate number of stormwa- Stll Creek 0 ter management controls, high levels of Brer Dtch  stream channel erosion and old sanitary Northeast Branch  sewer systems all contribute to the prob- Lower Beaverdam Creek 0 lem (Figures 20-21) . Watts Branch 0 Fort Dupont  As seen in Figure 22, the TSS Load to Pope Branch  Hckey Run 

Sligo Creek is estimated to be approxi- 0 0 00 0 000 mately 85 tons/year/square mile. The Phosphorus (lbs/year/square mile) Figure 23. Sligo Creek: Estimated Phosphorus Load average Anacostia subwatershed TSS load is 99 tons/square mile/year. Slgo Creek 

At elevated levels, two nutrients, phospho- Northwest Branch  rus and nitrogen, can negatively impact Pant Branch  freshwater ecosystems). High nutrient Lttle Pant Branch  loads can (by triggering algal blooms, Indan Creek 0 Beaverdam Creek  followed by subsequent die-off and de- Stll Creek  composition) greatly reduce the dissolved Brer Dtch  oxygen (DO) level of the water; thereby Northeast Branch 00 killing fish and other aquatic life. Nutri- Lower Beaverdam Creek 0 ents can originate as either point sources Watts Branch 0 (i.e., well-defined sources such as facto- Fort Dupont 0 Pope Branch  ries and sewage treatment plants with pipe Hckey Run 0 discharges) or as nonpoint sources (i.e., 0 000 000 000 000 0000 diffuse sources such as lawns, septic sys- Nitrogen (lbs/year/square mile) tems, farms, and the atmosphere). Typical Figure 24. Sligo Creek: Estimated Nitrogen Load

-25- Appendix 3- Sligo Creek sources of phosphorus and nitrogen include fertilizers, human and animal wastes, automotive exhaust, organic material, soil, etc.

As seen in Figure 23, the phosphorus Load to Sligo Creek is estimated to be approximately 530 lbs/square mile/year. The average Anacostia subwatershed phosphorus load is 500 lbs/square mile/year. A completely forested watershed would be expected to generate approximately 8.2 lbs/year/square mile.

The nitrogen load to Sligo Creek has been estimated to be approximately 5,884 lbs/square mile/year (Fig- ure 24). The average Anacostia subwatershed nitrogen load is 5,255 lbs/square mile/year. A completely forested watershed would be expected to generate approximately 42 lbs/year/square mile.

Note: The preceding loading rate are based on 2006-7 ICPRB HSPF modeling conducted as part of the MDE Anacostia sediment and nutrient TMDL’s. Toxics Toxics refer to a variety of contaminants including but not limited to: 1) trace metals such as arsenic, mercury, copper, cadmium and lead; and 2) organic compounds such as PAH’s (polycyclic aromatic hy- drocarbons), PCB’s (polychlorinated biphenyls) and pesticides and herbicides (e.g., DDT, Chlordane and atrazine). The preceding contaminants enter receiving waters from stormwater runoff, atmospheric de- position and industrial and municipal discharges. As there currently is minimal toxics-related monitoring data for the Sligo Creek subwatershed, the extent of this potential problem is unknown. There are a total of 119 NPDES-related industrial and municipal discharges in the Anacostia watershed. Eight of these (i.e., 6.7 percent) are located within the Sligo Creek subwatershed. Bacteria While long-term fecal bacteria data is unavailable for Sligo Creek and most of the Anacostia tributary sys- tem, limited fecal coliform grab sampling results strongly suggest that streams in the Anacostia watershed rarely, if ever, meet established bacterial water quality standards. Principal sources of fecal bacteria and relative contributions (MDE 2007) for the Anacostia’s two largest tributaries (i.e., Northeast and North- west Branch) are as follows: 1) human (9-55 percent), 2) domestic animals (24-28 percent), 3) livestock (6-28 percent) and 4) wildlife (12-38 percent). It should be noted that as part of a 2006 EPA Consent Decree, WSSC is required to rehabilitate its sewer line system within the Maryland portion of the water- shed within a 12-year period. It is also required to develop a water quality management plan (WQM) and perform semi-annual (spring and fall) bacterial source tracking at 17 tributary system monitoring sites (in the Maryland portion of the watershed), including two Sligo Creek stations (Figure 25).

-26- Appendix 3- Sligo Creek Figure 25. Sligo Creek: Stream Monitoring Stations, 2000-7*

Arcola A ve Colt Terrace Trb.

U Upper nver sty

G

e

o r Blvd g  a

A Breewood

v e Local Park S Trb.

W h e a to n

Br an ch

¨¦§495 Slgo GC Trb. Flora Lane Trb.

Bennngton Woodsde Park Branch Trb. d R Mddle

L e l o l  n v g s e l Greenbrer o C Drve Trb. Rd Legend Streams Open B

r a Pped h n c c n h a r Subwatershed Unt B y e n Parksde Road Cty of Takoma Park P Trb. . .

o o

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)" G Bactera (~) Maple Avenue n o e

c Trb. M n  r

!( P Macronvertebrate/Fsh (~) e v Lower G A Corbcula Clams/Toxcs (~) M S D o s n t tg r o ct m # o Temperature (~) f e S C ry o C ch lu o n m . S ra b B Sedment (~) a a S om d Tak R

e XY Trash Montorng () r  s h g s g p R m a Rollngcrest H w Trb. e Raydale Road N ± Trb.  0 0.  Source: MWCOG 00* Mles * Does not nclude volunteer montorng efforts by AWS and others

-27- Appendix 3- Sligo Creek Figure 26. Sligo Creek: COG Trash Survey Results, 2003-71

Trash Index Verbal Ranking No. Items/100ft. Color Code Arcola A ve Colt None- V. Light 0 – 10.0 Terrace Trb. Light 10.1 - 25.0 U Upper nver sty Moderate 25.1 – 50.0

G

e

o r vd g Bl High >=50.1  a Pant Branch Breewood A v Local Park e Trb.

W h e a to n

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¨¦§495 Slgo GC Trb. Flora Lane Trb.

Bennngton Woodsde Park Branch Trb. d R Mddle

L e l o l  n v g s e l Greenbrer o C Drve Trb. Rd

B

r a h n c c n h a r B y e n Parksde Road P Trb. . .

o o

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e e

g m r

o o

g e t Maple Avenue n G o e

c Trb. M n  r e P Legend v Lower A

Streams M D o s n t tg r o ct m Open o f e C ry o C ch lu o n Pped m . ra b B a a om d Subwatershed Unt Tak R

e r s h g Cty of Takoma Park s g p R m a Rollngcrest H w Trb. e Raydale Road N ± Trb. 0 0.   Mles Source: MWCOG 00

-28- Appendix 3- Sligo Creek 5.0 Trash Years of trash surveying in the Sligo Creek subwatershed, by COG and others, have resulted in the identi- fication of several chronic trash hot spot areas (i.e., stream segments with routinely high trash levels). As seen in Figure 26, stream areas currently exhibiting moderate to high trash levels include Wheaton Branch (above Dennis Avenue), Flora Lane tributary (all), Long Branch (below Piney Branch Road), Takoma Branch (below Ray Road), the Raydale Road tributary and the lower Sligo Creek main stem (below east- West Highway). The trash surveys show a distinct downstream trash trend and demonstrate the effective- ness of both the University Boulevard and Wheaton Branch stormwater management facilities in captur- ing floating trash (Figure 27). Survey results further indicate that watershed-wide, plastic bags, plastic bottles and styrofoam products are the top three trash items present in Sligo Creek.

Figure 27. 2003 Sligo Creek Downstream Trash Trend Sligo Creek Mainstem: Downstream Trash Trend (Spring 2003)

00

Relative 0 84.1 Abundance 0 68.7 0

0 High

0 42.5 38.8 0 Moderate 27.0 29.1 0 23.1

0 17.9 Light 11.8 5.7 Total No. Items/100-ft 0 None-V.Light 0 Channing S-1 Univ. S-2 Univ. Wheaton S-3 Forest I-495 S-4 Flora Colesville S-5 Wayne Piney Br. S-6 Carroll S-7 New S-8 East S-9 Riggs S-10 Dr. Blvd. SWM Blvd. Br. Glen Rd. Lane Trib. Rd. Ave. Road Ave. Hampshire West Hwy Rd. Facility Ave.

A. Probable Sources

Observations by COG and others indicate that much of the trash entering Sligo Creek originates in high use areas such as commercial shopping centers, higher density residential areas, convenience store and fast food establishments and major roadways. To a lesser and more local extent, illegal dumping and the littering of stream valley park picnic grounds, athletic fields and recreation facilities are also problematic. In an attempt to quantify the contribution from roads, COG staff conducted a roadside trash survey in 1999. The survey, which yielded 7,699 trash items, included approximately 12,800 linear feet along eight roads at their Sligo Creek crossings and along a segment of Sligo Creek Parkway. Like trash levels in the streams, roadside trash levels were found to be highest in the bottom half of the subwatershed. High road- side trash levels were not strongly correlated with traffic volumes.The preceding results provide further evidence that human behavioral factors, such as littering, are involved.

-29- Appendix 3- Sligo Creek 6.0 Provisional Fish Species List The resident fish population in Sligo Creek has changed dramatically over the years, as development in the watershed converted forests and fields into buildings and roads.The provisional fish list indicates which species of fish can be found in the Piedmont and Coastal Plain sections of Sligo Creek.While 39 different species of fish are thought to have once called the Piedmont portion of Sligo Creek home, currently approximately 14-18 species are present (Table 4). The resident fish population in Sligo Creek has actually experienced an upswing in recent years, as water quality and aquatic habitat improvements, together with the removal/modification of fish blockages in the lower main stem have created condi- tions suitable for more fish species. Fish re-introductions by Montgomery County DEP, COG, ICPRB, M-NCPPC and MDDNR have been successful in increasing the diversity of fish species in Sligo Creek. General Anacostia Restoration Potential Workgroup (ARPW) recommended 2010 Sligo Creek biological restoration targets are provided in Table 5. As seen in Table 5, a more restored Sligo Creek may be able to support approximately 20-25 fish species, total.

Table 4. Sligo Creek: Provisional List of Resident and Migratory Fishes Collected or Expected (1898 -2006)

Species Origin Status Piedmont Coastal Plain

Lampreys (Pteromyzontidae) . Amercan brook lamprey N R P P . Least brook lamprey N R P P . Sea lamprey N M P P

Eels (Anguillidae) . Amercan eel N M/R H, ● H,●

Herrings (Clupeidae) . Gzzard shad N R P . Blueback herrng N M P . Alewfe N M P

Mudminnows (Umbridae) . Eastern mudmnnow N R P

Minnows (Cyprinidae) . Common carp I R P 0. Goldfsh I R P,● P,● . Slverjaw mnnow N R P P . Cutlps mnnow N R P,● P . Golden shner N R P,● P . Rosysde dace N R H,● P . Ironcolor shner N R P . Brdle shner N R P . Swallowtal shner N R P,● P,● . Comely shner N R P P . Rosyface shner N R P P 0. Spotfn shner N R P H,● . Satnfn shner N R P,● P,● . Common shner N R P P . Spottal shner N R P P,● . Eastern slvery mnnow N R P P . Bluntnose mnnow N R P P . Blacknose dace N R H,● H,● . Longnose dace N R H,● H,● . Northern creek chub N R H,● H,● . Fallfsh N Stocked P,● P 0. Fathead mnnow I R P P . Central stoneroller N R P,● P

-30- Appendix 3- Sligo Creek Table 4. Sligo Creek: Provisional List of Resident and Migratory Fishes Collected or Expected (1898 -2006)

Species Origin Status Piedmont Coastal Plain

Suckers (Catostomidae) . Whte sucker N R P,● P . Northern hogsucker N R P,● P

Catfishes (Ictaluridae) . Yellow bullhead N R P,● . Brown bullhead N R P,● P . Tadpole madtom N R P P . Margned madtom N R P P

Trout-Perches (Percopsidae) . Trout-perch N R P P

Killifishes (Fundulidae) . Mummchog N R P 0. Banded kllfsh N R P

Sculpins (Cottidae) . Blue Rdge sculpn N R P P . Potomac sculpn N R P P

Sunfishes (Centrarchidae) . Rock bass I R P P . Green sunfsh N R P,● P,● . Bluegll sunfsh IP R P,● P . Redbreast sunfsh N R P P . Longear sunfsh N R P P . Pumpknseed sunfsh N R P P,● . Largemouth bass I R P P

Perches (Percidae) 0. Fantal darter N R P,● . Tessellated darter N R P,● P,● . Sheld darter N R P P . Log perch N R P Total No. of Historical/Current Species 39/15 51/13

Key Abbrevatons:

N = natve; I = ntroduced; IP = probably ntroduced; R = resdent; M = mgratory; H= hstorcal presence documented; P = probable hstorcal presence; ● = collected snce 

-31- Appendix 3- Sligo Creek air) (Fair) 2(Fair) Proposed ScoreRange AdjustedIBI Rating Verbal Excellent Fish oor) 2.2-3. oor) 2.2-3.2(F Score Scores Existing . – .0 .0 – . Poor . – Good . – . Far AdjustedIBI ResidentFish 1,2,3 Taxa Total Rating Verbal Proposed IBI SCORE IBI INTERPRETATION BenthicOrganisms Taxa Total 8--16 Poor No. of No. Scores 26– 34 Good 35 –40 Excellent 17– 25 Fair Existing 14 15-20 1.4(P 9 15-20 1.4(P Range Adjusted Proposed IBIScore 12-17 (Poor/Fair) 6-9 5-10 1.7(Poor) 1.6-2.2(Poor/Fair) IBI Score Existing Adjusted air) 13.0(Poor) 12-18(Poor/Fair) Macroinvertebrate(Spring) Proposed TotalTaxa System Mainstem Biological Community Targets Restoration 8-15(Fair) 13.5(Poor) 12-18(Poor/Fair) 24 24 20-24 (Good) 12.9(Poor) 12-18(Poor/Fair) 14 20-25 2.0(Poor) 2.2-3.2(Fair) Taxa Total No. of No. Existing 25 = Excellent,16-24 = Good,8-15 =Fair, 0-7=Poor. •

M-NCPPC 18 18-20 (Good) 13.0 (Poor) 13-17 (Poor/Fair) 6-12 5-15 2.2(Poor) 2.1-3.2(Poor/Fair) M-NCPPC 7 8-15(Fair) 12.0 (Poor) 12-17 (Poor/Fair) 9 5-10 2.4(Fair) 2.4-3.2(Fair) M-NCPPC 7 8-15(Fair) --- 12-17 (Poor/Fair) 2 2-4 1.4(Poor) 1.4-2.1(Poor) M-NCPPC --- 8-15(Fair) --- 12-17 (Poor/Fair) 1 5-10 1.0(Poor) 1.0-2.1(Poor) M-NCPPC 6 8-15(Fair) 12.0 (Poor) M-NCPPC 19 ExistingMonitoring Program/Station ID# oresare adjusted toMCDEP ratingscale. em em andtributary adjusted IBIscores. mber of mber macroinvertebratetaxa: Total SubwatershedMainstems General interpretation forthe nu Adjusted macroinvertebrateand fish sc IBI totalSum isanaggregate of mainst SligoCreek Upper(above Colesville Rd.) Middle(Colesville Rd.toNew Hampshire Ave.) Lower (NewHampshire Ave. to NW Branch) M-NCPPC Tributary PGDER/14-001 WheatonBranch 7 FloraLane Tributary 11 WoodsidePark Tributary 16-24 (Good) LongBranch 8-15(F 13.1 (Poor) BranchTakoma (PG CO) 12-18(Poor/Fair) 14 20-25 1.8(Poor) 2.2-3.2 Table 5. 2005 Summary: ARPW 2010 Recommended Anacostia Tributary 1 2 3 Note:More recent electrofishingsuggest surveys 14-18 fish species present

-32- Appendix 3- Sligo Creek 7.0 Restoration Projects

Since much of the Sligo Creek subwatershed was developed before stormwater controls became manda- tory, many of the restoration projects that have been implemented in this subwatershed were designed to retain and treat stormwater through both traditional stormwater management techniques (e.g., ponds, wetlands, etc.) and low impact development (LID). The 20-plus riparian reforestation plantings conducted since 1998 by M-NCPPC, COG, FOSC and MDDNR have also served to treat and retain stormwater, while providing habitat for wildlife. Stream restoration projects have been implemented to reduce ero- sion and improve fish passage. Figure 28 depicts a subset of all of the restoration projects that have been completed in Sligo Creek. Several more restoration projects are in the planning or design stages. Tables 6 and 7 provide insight as to how Sligo Creek compares to the remainder of the Anacostia watershed both in terms of the amphibian community and general environmental problems.

Figure 28. Sligo Creek: Select Restoration Projects1

Select Restoration Projects: cola Ar Av e Colt (1989 - Present) Terrace Trb. .! SWM Retroft Ste (~)

U Upper nver Stream Restoraton (~) sty .! Fsh Passage (~) G #*

e

o r Blvd g l Rapran Reforestaton (~)  a Breewood Pant Branch A v Local Park e \ Wetland Creaton/Restoraton (~) Trb. ^_ W Fresh Creek Trash Net (~) h e a to n .!.!.! .! .! Br an ch

.! .! ¨¦§495 .! Slgo GC Flora Lane .! Trb. Trb. .!

Bennngton Woodsde Park Branch Trb. d R .! Mddle L e l o l  n v g s e l Greenbrer o C Drve Trb. Rd

B r a h c n n c a h r B y e n P Parksde Road

Trb. . .

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Maple Avenue n G

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Subwatershed Unt e r .! s #* h g #* s g p R # Cty of Takoma Park m * a Rollngcrest H w Trb. #* e Raydale Road N ± Trb. 0 0.   Mles Source: MWCOG 00

-33- Appendix 3- Sligo Creek Table 6. Confirmed, Expected and/or Possible Amphibian Species*

Location in Watershed Anacostia Salamanders Scientific Name Upper Middle Lower Watershed 1. Greater Siren Siren leacertina U U U P 2. Red-Spotted Newt Notopthalmus viridescens U U U E 3. Spotted Salamander Ambystoma maculatum C P P C 4. Marbled Salamander Ambystoma opacum U U U C 5. Northern Dusky Salamander Desmognathus fuscus C C C C 6. Northern Two-Lined Salamander Eurycea bislineata C C E C 7. Longtail Salamander Eurycea longicauda U U U C 8. Four-Toed Salamander Hemidactylium scutatum U U U C 9. Redback Salamander Plethodon cinereus U U U C 10. Slimy Salamander Plethodon glutinosus C P P C 11. Eastern Mud Salamander Pseudotriton ruber U U U C 12. Northern Red Salamander Psuedotriton ruber U U U C Frogs and Toads 13. Eastern Spadefoot Toad Scaphiopus holbrookii U U U C 14. Eastern American Toad Bufo americanus C C C C 15. Fowler's Toad Bufo woodhousii P P P C 16. Northern Cricket Frog Acris crepitans U U U C 17. Green Tree Frog Hyla cinera U U U P 18. Northern Spring Peeper Pseudacris crucifer C U P C 19. Gray Treefrog Hyla versicolor C U P C 20. Striped Chorus Frog Pseudacris triseriata U U U C 21. Bullfrog Rana catesbeiana C E E C 22. Green Frog Rana clamitans C E E C 23. Pickerel Frog Rana palustris C E E C 24. Southern Leopard Frog Rana sphenocephala U U P C 25. Wood Frog Rana sylvatica C U P C

Interpretation: C Confirmed E Expected P Possible U Presence Highly Unlikely *This list, updated with FrogWatch results from 2005, was compiled by the Metropolitan Washington Council of Governments in 1998 with reference to Herbert S. Harris, Jr., "Distributional Survey (Amphibia/Reptilia): Maryland and the District of Columbia," in Bulletin of the Maryland Herpetological Society, vol. 11, no. 3 (30 Sept. 1975); and on Athanas, C. & Assoc., Inc, 1998; Buchart-Horn, Inc., 1989; Fowler, A., 1945; Galli, J., 1998; Harris, H.S., 1969; Hill, J. & G.B. Mackieman, 1989; Univ. of MD College Park, 1993.

-34- Appendix 3- Sligo Creek

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i l S =yes 25%) • t Problem Category Actual construction or manage a contract Poor Quality or Non-Functional Wetlands Severely Disrupted Hydrologic Regime (Impervious Cover Poor or no In-Stream Aquatic Habita 1 1 2 Stormwater Runoff 3 Excessive Erosion/Deposition 4 Low or No Base Flow 5 Sewer System Leakage/Overflow 6 Combined Sewer Overflow 7 Point Source Pollution (NPDES) 8 Fish Blockage (complete) 9 Fish Blockage (partial) 11 12 Loss of Wetland Habitat 13 Loss of Riparian Habitat 14 Loss of Upland Forest Habitat 15 Invasive Non-Native Species 16 Loss of SAV Habitat 17 Trash 18 Other 10 Table 7. Anacostia Tributaries: General Problem Category Summary, 2007 Category Summary, General Problem Tributaries: Anacostia 7. Table

-35- Appendix 3- Sligo Creek Sligo Creek Subwatershed: Provisional Restoration Project Inventory

PREPARED FOR: ANACOSTIA WATERSHED RESTORATION PARTNERSHIP

PREPARED BY: DEPARTMENT OF ENVIRONMENTAL PROGRAMS METROPOLITAN WASHINGTON COUNCIL OF GOVERNMENTS

AUGUST 14, 2008 V. 2 (UPDATED AS OF JULY 20, 2009) Sligo Creek Subwatershed:

Provisional Restoration Project Inventory

PREPARED FOR:

ANACOSTIA WATERSHED RESTORATION PARTNERSHIP

PREPARED BY:

JOHN GALLI, PHONG TRIEU, AUBIN MAYNARD AND KERRY CHOI

DEPARTMENT OF ENVIRONMENTAL PROGRAMS

METROPOLITAN WASHINGTON COUNCIL OF GOVERNMENTS

AUGUST 14, 2008

(UPDATED AS OF JULY 20, 2009) Acknowledgements

The authors wish to thank a number of organizations and individuals for their many contributions to this inventory. First and foremost, we would like to thank the Montgomery County Department of Environmental Protection (MCDEP), the Prince George’s County Department of Environmental Resources (PGDER) and the District of Columbia Department of the Environment (DDOE) for providing the fi nancial support necessary to make this project possible. Furthermore, we wish to especially thank the Anacostia Watershed Restoration Plan Team: Ms. Mary Dan (Team Leader), Mr. Dave Robbins and Ms. Angie Sowers (all U.S. Army Corps of Engineers, Baltimore District), Mr. Dan Harper and Mr. Craig Carson (both MCDEP), Dr. Mow- Soung Cheng, and Mr. Jerry Maldonado (both PGDER), Mr. Pete Hill (DDOE), Mr. Ken Yetman (Maryland Department of Natural Resources), Mr. Paul Emmart and Mr. Jim George (both Maryland Department of the Environment), Mr. Doug Redmond (Maryland-National Capital Park and Planning Commission-Montgomery County), Ms. Laura Connelly (Maryland-National Capital Park and Planning Commission-Prince George’s County), Ms. Dana Minerva (Executive Director, Anacostia Watershed Restoration Partnership) and Ms. Mary Barber (Chair, Anacostia Watershed Citizens Advisory Committee) for providing technical coordination, support and guidance and assisting COG staff in conducting site visits. Contributions to the inventory, from the Friends of Sligo Creek (Mr. Bruce Sidwell, Mr. Mike Smith, Mr. Ed Murtagh, Ms. Wendi Schauffner and Ms. Sally Gagne) and the Anacostia Watershed Society (Mr. Masaya Maeda), are also greatly appreciated. Finally, the authors would like to extend their appreciation to Mr. Stuart Freudberg and Dr. Edward Graham (both COG) for their support. Table of Contents

Acknowledgements

I. Background ...... 1

II. Methods ...... 2

III. Restoration Inventory ...... 5

I. Impervious Features Summary ...... 7

II. Existing Stormwater Management ...... 10

III. Candidate Restoration Project Summary ...... 13

IV. Upper Sligo - Candidate Restoration Projects...... 16

V. Middle Sligo - Candidate Restoration Projects ...... 39

VI. Lower Sligo - Candidate Restoration Projects ...... 61

VII. Restoration Project Samples ...... 84

VIII. References ...... 93 I. Background

The 11 square mile Sligo Creek subwatershed (MD#021402050821) is one of the most heavily urbanized tributaries (i.e., approximately 33 percent impervious) in the 176 square mile Anacostia River watershed (HUC# 02070008, MD#02140205). As seen in Figure 1, the Sligo Creek subwatershed drains portions of Montgomery County, Prince George’s County and the District of Columbia. This multi-jurisdictional subwatershed represents one of the many older built out portions of the Anacostia watershed, having been largely developed during the 1930’s- 50’s; well before the advent of stormwater management controls. Although there have been many various restoration projects constructed in Sligo Creek since 1990, water quality and aquatic habitat and terrestrial habitat remains degraded. Specifi cally, Sligo Creek exhibits moderate to high TSS, nutrient and bacteria loadings, generally poor IBI scores for both macroinvertebrates and fi sh, and one of the worst trash problems in the Anacostia watershed.

Recognizing both the severity and extent of environmental-related problems throughout the Anacostia watershed and the need to better coordinate restoration efforts and resources, the Anacostia Watershed Restoration Partnership (in September 2007) entered into a federal cost- sharing agreement with the U.S. Army Corps of Engineers to prepare, by November 2009, an Anacostia Watershed Restoration Plan. The Restoration Plan will identify (at a conceptual, planning level) both structural and non-structural approaches for restoring both the tidal river and the Anacostia’s 14 major subwatersheds. First year products include the preparation of the “Anacostia Watershed Environmental Baseline Conditions and Restoration Report,” an “Interim Restoration Report,” and a “Draft-Sligo Creek Subwatershed Action Plan” (S-SWAP). When completed, the S-SWAP will serve as the ‘blueprint’ for the restoration of Sligo Creek. As a companion piece to the S-SWAP, the “Sligo Creek Subwatershed: Provisional Restoration

Figure 1 - Sligo Creek Subwatershed Figure 2 - Sligo Creek Subwatershed Unit

1 Project Inventory” provides a suite of potential stormwater retrofi t, stream restoration, wetland creation/restoration, fi sh blockage removal/modifi cation, riparian buffer restoration, invasive plant management, and wildlife habitat improvement projects, land acquisition and other measures for further evaluation and possible follow-up action.

The Sligo Creek subwatersehd restoration project inventory consisted of eight general tasks, employing the following approaches: 1) land use/land cover/imperviousness analyses, 2) evaluation of existing storm drainage and stormwater controlled areas, 3) a review of existing/ known restoration inventories and problem areas, 4) Watershed Treatment Model (WTM) modeling results integration, 5) low level aerial photographic interpretation, 6) actual fi eld surveying/candidate project site identifi cation, 7) GIS candidate project map/database creation, and 8) project cost estimation and ranking. In addition, input from FOSC and AWS members was incorporated. Detailed task-by-task accomplishments and results are presented herein.

II. Methods

The following section describes the eight-step process employed by COG staff in preparing the inventory.

Step One - Land Use/Land Cover/Imperviousness Analyses

• Acquired 2002 Maryland Department of Planning (for Montgomery and Prince George’s Counties) and 2002 District of Columbia Offi ce of the Chief Technology Offi cer (DC- OCTO) land use/land cover spatial data;

• Using Maryland Department of Planning (MDP) classifi cation categories, standardized jurisdictional land use/land cover data;

• Using 2004-5 low level aerial orthophotographs, verifi ed (and where necessary corrected) MDP and DC-OCTO Land Use/Land Cover spatial data;

• Obtained (from USGS) 30-meter digital elevation model (DEM) data for entire subwatershed;

• Subdivided the Sligo Creek subwatershed into three major hydrologic unit areas (i.e., Upper, Middle and Lower);

• Delineated both major (fi ve, total) and minor (four, total) Sligo Creek subwatersheds. Major Sligo Creek subwatersheds include: 1) Wheaton Branch, 2) Flora Lane tributary, 3) Woodside Park tributary, 4) Long Branch and 5) Takoma Branch. Minor Sligo Creek subwatersheds include: 1) Colt Terrace tributary, 2) Breewood Local Park tributary, 3) Parkside Road tributary and 4) Raydale Road tributary;

• Acquired Maryland-National Capital Park and Planning Commission (for Montgomery

2 and Prince George’s Counties) and District of Columbia Offi ce of the Chief Technology Offi cer (DC-OCTO) imperviousness feature spatial data (i.e., building footprints, road and sidewalk surfaces, paved parking lot surfaces, etc);

• Developed a series of imperviousness features/attributes layers for: 1) the entire subwatershed, 2) the three main hydrologic unit areas, 3) major subcatchments and 4) minor subcatchments. Impervious surfaces were broken down into the following categories: 1) roads (public and private), 2) parking lots (public and private), 3) roofs (public and single family residential), 4) private residential driveways and 5) sidewalks. It should be noted that the average residential square footage was estimated through a GIS/ aerial photo interpolation analysis of a representative Upper Sligo Creek subdivision;

• Created a Sligo Creek GIS geodatabase (spatial features and associated attributes tables) for the entire Sligo Creek subwatershed; and

• Developed a series of Sligo Creek summary maps depicting existing Land Use/Land Cover/Imperviousness conditions.

Step Two - Existing Storm Drainage and Stormwater Management Controlled Area Analysis

• Obtained stormwater retrofi t location and storm drainage attributes data (e.g., type of facility, year constructed, drainage area, storm drain pipe diameter and length, etc) from all three jurisdictions;

• Using Prince George's County's 5-foot interval topoline GIS dataset and storm drain pipe system information, delineated stormwater BMP drainage areas within the County portion;

• Populated storm drain outfall attributes table, where necessary;

• Performed limited ground-truthing to verify presence of select, smaller BMP’s and storm drain outfalls; and

• Developed ‘existing stormwater management controlled area’ GIS layers and associated summary attribute tables.

Step Three - Review of Existing Restoration Inventory and Watershed Problem Information

• Obtained restoration-related inventory data for all three jurisdictions;

• Obtained watershed problem-related survey information from MDDNR (Sligo Creek Stream Corridor Assessment), invasive plants (M-NCPPC) and other data from all three jurisdictions; and

3 • Reviewed both potential restoration project sites and problem areas and compiled information into a Sligo Creek GIS database.

Step Four - WTM Pollutant Modeling Results Interpretation

• Obtained from the Corps, Center for Watershed Protection Watershed Treatment Model (WTM) modeling run results for Sligo Creek; and

• Reviewed WTM loading data, and cross-referenced with data generated from Steps 1-3 to further screen potential stormwater retrofi t need/opportunity areas.

Step Five - Low Level, High Resolution Aerial Photography Interpretation

• Obtained (from M-NCPPC, both Montgomery and Prince George's Counties, and DC- OCTO) low level, 2004-5 aerial orthophotographs for all three Sligo Creek jurisdictions;

• Reviewed WTM loading data, and cross-referenced with data generated from Steps 1-4 to further screen potential stormwater retrofi t need/opportunity areas; and

• Transferred potential restoration project site area information onto high resolution, 1 inch=500 feet color aerial photographic paper prints.

Step Six-Field Survey/Site Visit

• Prior to going out in the fi eld, developed standard restoration project form to log candidate restoration project information. This information included the following: 1) project identifi cation number, 2) jurisdictional location, 3) project name, 4) ADC map book location, 5) project type, 6) ownership, 7) approximate drainage area, imperviousness and/or length or acreage, 8) a general description of the COG recommended restoration technique(s), 9) estimated cost, 10) project score and 11) project ranking;

• Performed both 'windshield’ and walking surveys of candidate restoration sites; Figure 3 - COG Staff Collecting Candidate Lo- • Used Trimble GeoXH GPS unit to cation Coordinates Using a GPS Receiver

4 generate latitude and longitude, in decimal degrees, location coordinates for candidate sites;

• Using digital cameras, took representative photographs of candidate sites and surrounding area;

• Located actual potential project sites onto 1 inch=500 feet color aerial photographic prints; and

• Completed fi lling in project form.

Step Seven - GIS Candidate Restoration Project Map/Database Creation

• Using desktop ArcView 9.2, imported the location coordinate feature point data for candidate sites;

• Populated associated attribute data table with completed project form information;

• Digitized both candidate site approximate drainage and imperviousness areas;

• Developed the Sligo Creek candidate restoration project geodatabase; and

• Developed a series of Sligo Creek candidate restoration project maps for Sligo Creek and its major and minor subwatersheds.

Step Eight - Project Cost Estimation and Prioritization

• Using construction and programmatic cost data obtained from all three jurisdictions (as well as other sources), estimated costs for all candidate projects; and

• Applied the Anacostia Watershed Restoration Plan Team’s project numerical scoring/ prioritization system.

III. Restoration Inventory

The following sections include stormwater retrofi t, stream restoration, wetland creation/ restoration, fi sh blockage removal/modifi cation, riparian buffer restoration, invasive plant management, and wildlife habitat improvement projects, land acquisition and other-related projects and actions for further evaluation by Montgomery County, Prince George’s County, the District of Columbia and others. As previously noted, the restoration projects presented herein are conceptual or planning level, only. It is recognized that more detailed drainage and site analyses are required, and that facility size and costs shown represent approximations by COG staff. To facilitate reader understanding of the Sligo Creek Subwatershed: Provisional Restoration

5 Project Inventory, information has been organized into the following eight sections: Section I - Impervious Features Summary, Section II - Existing Stormwater Management Facilities Summary, Section III - Candidate Restoration Project Summary, Section IV - Upper Sligo Creek, Section V - Middle Sligo Creek, Section VI - Lower Sligo Creek, Section VII - Restoration Project Samples and Section VIII - References. One standard format describing: site location/description, drainage area, proposed technique, available treatment area, project goal(s), general concept and site specifi c notations was employed. In addition, Section VII provides examples of potential low impact development (LID) and traditional stormwater management retrofi ts, stream restoration, wetland/vernal pool creation, fi sh passage removal/modifi cation, trash reduction and other Best Available Technologies (BAT’s) and techniques. Section VIII provides a list of references used in the inventory.

6 I. Impervious Features Summary

7 Figure 4 - Summary: Sligo Creek Impervious Features

8 Table 1. Sligo Creek: Summary - Impervious Surfaces1

Associated Category Acreage (ac) 1. Roads (miles/acres) 204.0 mi/795.2 ac a. State/Federal 21.5 mi/186.8 ac b. Local 182.6 mi/608.4 ac 2. Parking Lots: 383.3 ac a. Public/Institutional 205.6 ac b. Private 177.7 ac 3. Roofs 846.7 ac a. Public/Institutional 172.6 ac b. Private (Non-Single Family) 146.5 ac c. Single Family Homes 527.6 ac 4. Other a. Single Family Driveways* 261.5 ac b. Sidewalks** 88.5 ac Total 2,375.2 ac Avg. Percent Imperviousness (%) 34% No. of Single Family Homes 18,677 1Note: Sligo Creek D.A.= 7,085 acres

*Driveways area assumption: Average Driveway = 600 sq. ft.

**Sidewalks area assumptions: Width equal to 4 ft. Sidewalks run length of roads At least one side of road has si

9 II. Existing Stormwater Management Facilities Summary

10 Figure 5 - Sligo Creek: Stormwater Management BMP Sites, 2007

11 Table 2. Sligo Creek: Summary - Sligo Creek Stormwater Management BMP’s, 2007 No. of Percent of D.A. Controlled Type Facilities Total BMP's (ac.) 1. Dry Pond 78.0%22.7 2. ED Dry Pond 3. Wet Pond 4. ED Wet Pond 3 3.4% 1,306.0 5. Wetland (non-ED and ED) 33.4%56.9 6. Infiltration (Trench or Basin) 19 21.8% 23.1 7. Oil Grit Separator 22 25.3% 37.6 Water Quality Inlet (e.g. 8. Stormreceptor, Bay Saver, etc) 9 10.3% 12.1 9. Bioretention /Rain Garden 78.0%15.7 10. 'Green Street'* 1 1.1% 1.0 11. Biofiltration Swale 1 1.1% 4.3 12. Grass Swale w/ Check Dams 13. Porous Pavement 14. Sand Filter 89.2%11.7 15. Underground Pipe Storage 44.6%11.4 16. Cistern 17. Green Roof 18. Other 3 3.4% 2.4 Total 87 100.0% 1,505.0 May include a mix of LID techniques including, but not limited to: bioretention, * raingarden, biofiltration swale, soil ammendment, etc.

12 III. Candidate Restoration Project Summary

13 Table 3. Summary: Restoration Candidate Projects

Impervious Number Estimated Acreage Length Acreage Candidate Project Type of Cost Controlled (mi) (ac) Projects ($) (ac) 1. Stormwater Retrofit 84 $34,986,385 287.5 2. Stream Restoration 13 $3,080,000 2.8 3. Wetland 12 $92,000 1.8 Creation/Restoration 4. Fish Blockage 23 $3,237,000 11.2 Removal/Modification 5. Riparian Reforestation, 17 $21,900 15.9 Meadow Creation, Street Tree and Invasive Management 6. Trash Reduction 21 $114,774 20.4 7. Toxic Remediation 0 8. Parkland Acquisition 1 $50,000 0.5 Total 171 $41,582,059 287.5 34.4 18.2

14 Table 4. Sligo Creek Subwatershed: Provisional Restoration Project Inventory ‘Unity Costs’ * No. Practice Approx. Unit Cost ($) Stormwater Retrofit Existing Stormwater Management 1 ~ $1,000-3,000/acre of drainage Pond/Wetland Retrofitting New Stormwater Management 2 ~$3,000-5,000/acre of drainage Pond/Wetland Construction 3 LID-Bioretention (w/Underdrain System) ~ $100,000/ impervious acre 4 LID-Curbside/Street Planter ~ $100,000/ impervious acre 5 LID-Tree Box Filter ~ $54,450 - $65,340/impervious acre 6 LID-Green Roof ~ $42/square foot 7 LID-Single Family Home Rain Garden ~ $5,000 per individual garden 8 LID-Single Family Home Rain Barrel ~ $200/barrel (Typically, two per house) 9 Sand Filter ~ $20,000 to $25,000 per impervious acre** 10 Underground Pipe Storage ~ $15,000 per impervious acre*** 11 Permeable Pavement ~ $4.00 per square foot 12 LID Bioswale ~ $100,000/impervious acre 13 Storm Filter ~ $80,000/acre Stream Restoration/Fish Passage/Wetland Creation 14 Stream Restoration ~ $300/LF 15 Concrete Stream Channel Removal ~ $1,000/LF 16 Stream ‘Day Lighting’ ~ $2,000/LF Regenerative Stormwater Conveyance 17 ~ $370/ft System Fish Passage/Riffle Grade Control 18 ~ $150,000 per one foot barrier height Structure 19 Wetland Creation ~$50,000/Acre Riparian Reforestation/Meadow Creation/ Invasive Plant Management 20 Riparian Reforestation ~ $9,000/acre 21 Wildflower Meadow Creation ~ $5,000/acre 22 Invasive Plant Management ~ $5,000/acre Trash Reduction/Water Quality 23 Manual Trash Pickup ~ $300/100 LF 24 Trash Netting System ~ $1,000/acre of drainage 25 Signage ~ $1600 26 End–of-Pipe Trash Catching System ~ $4,000/ acre of drainage 27 Street Sweeping**** ~ $50/curb mile/year 28 Storm Drain Trash Grate ~ $500/inlet Parkland Acquisition 29 Parkland Acquisition ~ $100,000/acre *includes (where appropriate) design and construction/installation costs ** escalated to 2009 dollars from “Schueler, T.R. 1994. Developments in Sand Filter Technology to Improve Stormwater Runoff Quality, Watershed Protection Techniques 1(2):47-54” *** USEPA 20001 Storm Water Technology Fact Sheet On-Site Underground Retention/Detention EPA 832-F-01-005 **** EPA-certified as water quality BMP

15 IV. Upper Sligo - Candidate Restoration Projects

(w/ representative photos)

16 Table 5. Upper Sligo Creek - Impervious Surfaces

Major Tributaries

Associated Category Acreage (ac) Wheaton Branch Flora Lane Tributary Woodside Park Tributary 1. Roads (mi/ac) 82.4 mi/347.8 ac 25.4 mi/105.3 ac 8.0 mi/38.5 ac 5.3 mi/20.1ac a. State/Federal 7.9 mi/88.1 ac 2.7 mi/24.8 ac 1.5 mi/18.5 ac 0.5 mi/4.3 ac b. Local 74.5 mi/259.7 ac 22.7 mi/80.5 ac 6.5 mi/20.0 ac 4.8 mi/15.8 ac 2. Parking Lots: 147.1 ac 71.5 ac 11.1 ac 5.8 ac a. Public/Institutional 89.5 ac 42.0 ac 10.5 ac 3.6 ac b. Private 57.6 ac 29.5 ac 0.6 ac 2.2 ac 3. Roofs 327.1 ac 114.3 ac 23.7 ac 26.5 ac a. Public/Institutional 58.1 ac 31.3 ac 4.9 ac 6.4 ac b. Private (Non-Single Family) 52.9 ac 28.4 ac 2.6 ac 3.4 ac c. Single Family Homes 216.1 ac 54.6 ac 16.2 ac 16.7 ac 4. Other a. Single Family Driveways* 98.0 ac 26.7 ac 7.3 ac 6.1 ac b. Sidewalks** 36.1 ac 11.0 ac 3.2 ac 2.3 ac Total 956.1 328.8 ac 83.8 ac 60.9 ac Avg. Percent Imperviousness (%) 32% 40% 37% 29% No. of Single Family Homes 7,000 1,906 524 438 Total D.A.= 2,950 ac 822 ac 227 ac 208 ac

*Driveways area assumption: Average Driveway = 600 sq. ft.

**Sidewalks area assumptions: Width equal to 4 ft. Sidewalks run length of roads At least one side of road has sidewalk

17 Figure 6 - Upper Sligo Candidate Stormwater Retrofi t Sites

18 Project Ranking (pts) Score Project 10,000 76 Medium 50,000 69 Medium 50,000 7750,000 Medium 74 Medium 475,904 56 Low 255,000 69 Medium 150,000 74 Medium Cost ($) 1,084,760 71 Medium 1,000,000 71 Medium 1,030,000 67 Medium Estimated Court Boxes Spreader Efficiencies of 42 Homes) LID 'Green Street' to Improve Removal Pond Modification*** General Description Rainscapes Targeted Sidewalk Pipe Storage Green Roof, Parking Lot Foundation & Parking Lot Aeration Feature Addition Off-Line Wetland or Level Outlet Pipe Modification & Bioretention & Tree Boxes Bioretention/Green Roof/and Greenstreet along Breewood Bioretention, Bioswale & Tree Road, Fiesta Breewood and Change Mowing Practices Ex. Median Strip Conversion to Landscape 1,500 LF of Swales Ex. Median Strip Conversion to Neighborhood Program (17 out LID 'Green Street' w/Bioswale & pprox. A % (ac) Impervious Approx D.A. (ac) t Projects t fi Ownership 1 1c Public 11.8 85.0 10.0 Type Project 36 J-2 1c Public 3.3 80.0 2.6 Parking Lot Bioretention 260,000 78 Medium 36 K-1 1c Public 431.0 23.0 99.1 36 G-2 1c Public 2.4 85.0 2.0 Parking Lot Bioretention 200,000 71 Medium Private 1bPrivate Private 1c 0.6 Private 98.0 0.6 0.6 Create Parking Lot Bioretention 98.0 100,000 0.6 Install Parking Lot Tree Box 76 100,000 Medium 69 Medium 30 J-13 1c Public 1.1 98.0 1.1 30 K-13 1b Public 29.0 20.0 5.8 Off-Line ED Wetland 145,000 68 Medium 30 G-13 1c Public 3.0 75.0 2.3 3; 37 B-3 Location 37 K-2; A-2 1c Public 3.0 17.0 0.5 37 K-2; A-2 1c Private37 K-2; A-2 8.5 1b 28.0 Public 2.4 8.4 54.0 4.5 Stormwater Wetland 42,500 76 Medium 36 K-2; 37 A-2, ADC Map Book Site) Name School Facility Lane*** NCPPC Tributary Neighborhood Center/School Stephen Knolls East Parking Lot Strip (~6,000 LF) Breewood Manor South Parking Lot Channing Drive/M- Swale Enhancement Colt Terrace/Daffodil Sligo Creek Parkway Breewood Local Park Library (Demonstration University Towers 1111 University Towers 1111 Glen Haven Elementary University Blvd Condos University Blvd Condos University BLVD Median Wheaton Regional Public Ex. University BLVD SWM Jurisdiction Project ID SC-U-01-S-6 MC SC-U-01-S-7SC-U-01-S-8 MC MC SC-U-01-S-1 MC SC-U-01-S-5 MC University Towers 37 A-1 1b Private 1.6 80.0 1.3 SC-U-01-S-9 MC SC-U-01-S-2SC-U-01-S-3 MC SC-U-01-S-4 MC MC Yates Street/M-NCPPC 30 K-13 1c Public 13.8 30.0 4.1 Off-Line ED Wetland 69,000 72 Medium SC-U-01-S-10 MC SC-U-01-S-11 MC SC-U-01-S-12SC-U-01-S-13 MCSC-U-01-S-14 MCSC-U-01-S-15 MC Breewood Road Breewood Road 2 MC 37 K-2; A-2SC-U-01-S-16 37 K-2; A-2 Ten Brook Road 1b 1b MC 37 K-2; A-2 Public 1b Public 0.4 Public 1.0 98.0 0.4 98.0 0.4 1.0 Bioretention on Cul-De-Sac 98.0 100,000 0.4 Bioretention on Cul-De-Sac 75 100,000 Medium 75 Medium SC-U-01-S-21 MC Karasik Child Care Center 36 B-2 1c Private 4.1 70.0 2.9 Parking Lot Porous Pavement 287,000 59 Low SC-U-01-S-19SC-U-01-S-20 MC MC Sligo M.S. Dennis Ave. Median 37 A-4; B-4 1c 36 K-4 Public 1c 5.1 Public 50.0 7.9 2.6 70.0 5.5 Parking Lot Bioretention 553,000 60 Low SC-U-01-S-17 MC SC-U-01-S-18 MC Northwood H.S. 37 A-2; B-2 1c Public 12.9 80.0 10.3 Table 6. Upper Sligo Creek: Candidate Stormwater Retro Candidate Stormwater Sligo Creek: 6. Upper Table

19 Project Ranking (pts) Score Project 10,000 65 Medium 50,000 66 Medium 50,00010,000 72 71 Medium Medium 20,000 79 Medium 25,000 70 Medium 10,000 77 Medium 274,200 69 Medium 190,000 73 Medium 224,000 68 Medium 376,000 68 Medium 304,200 67 Medium 220,000 77 Medium Cost ($) 2,099,520 64 Low Estimated Control Forebay Shoulder Planter(s) Bioretention Bioretention Bioretention Concrete Weir Notch Gully Erosion Control General Description Rainscapes Targeted LID 'Green Street' and LID 'Green Street' and Sidewalk Pipe Storage Separator to Sand Filter Separator to Sand Filter Modification & Sediment Storm Drain Outfall Level Neighborhood-44 Homes Spreader & Gully Erosion Conversion of Ex. Oil/Grit Aeration Feature Addition Conversion of Ex. Oil/Grit Aeration Feature Addition Outlet Pipe Modification & Outlet Pipe Modification & Green Roof & Parking Lot Bioretention/Bioswale/Filter Ball Field Level Spreader & Green Street LID/Bioswale & (Note: Ex. # SF Homes=438), Ex. Median Strip Conversion to Ex. Median Strip Conversion to Shoulder Bioretention/Curbside pprox. A % (ac) Impervious Approx D.A. (ac) (Continued) t Projects fi Total** 388.1 105.5 $10,382,984 Ownership 1 1c Private 208.2 29.3 13.2 Type Project 7, 8 37 J-6 1c Public 70.0 20.0 14.0 36 J-7 1c Private 3.8 90.0 3.4 36 J-4 1c Public 805.0 37.0 297.9 37 K-6 1c Public 10.1 30 3.0 37 K-6 1c Public 9.1 30 2.7 36 K-6 1a Public 225.0 35.0 78.8 37 A-6 1c Public 0.8 98.0 0.8 Parking Lot Bioretention 78,400 64 Low 37 B-6 1c36 K-9 Public 1b 0.6 Public 85.0 4.6 0.5 70.0 3.2 36 K-6 1c Private 2.0 80.0 1.6 Bioretention and Tree Boxes 160,000 65 Medium 37 B-636 K-3 1c 1a Public Public 3.5 1.3 40 10 1.4 0.1 Bioretention 140,000 65 Medium Location 36 J-8, K-8 1c Public 4.7 80.0 3.8 36 K-6; 37 A-6 1c Public 5.9 90.0 5.3 Off-Line ED Wetland 29,500 73 Medium 36 K-7, 8; 37 A- ADC Map Book 36 J-7, 8; K-6 1c Public 6.4 35.0 2.2 Lot Field Road Name Facility Parking Lot Intersection (~2,500 LF) Parking Lots Shopping Ctr SWM Facility Headquarters Neighborhood Flora Lane and Woodside Park Strip (~1,200LF) Lansdowne Way Montgomery Hills Holly Cross Hospital Capital Beltway East Ex. Wheaton Branch Ex.Flora Lane Parallel & Planning Place No.2 Columbia Blvd Median Flora Lane and Crosby M-NCPPC Parks Dept. Pipe System (~900 LF) Outer Loop (~1,700 LF) Dennis Ave. Recreation Sligo Creek GC Parking Bruce Drive/Thornhill Rd M-NCPPC MRO Building Ex. Sligo Creek GC SWM Georgia Ave. Median Strip Jurisdiction Project ID SC-U-01-S-24 MC SC-U-01-S-27 MC SC-U-01-S-36 MC SC-U-01-S-23 MC Belvedere Blvd. Median 36 J-5, K-2 1c Public 3.8 50.0 1.9 SC-U-01-S-25 MC SC-U-01-S-35 MC SC-U-01-S-26 MC SC-U-01-S-33 MC SC-U-01-S-22 MC SC-U-01-S-34 MC SC-U-01-S-30 MC SC-U-01-S-31 MC SC-U-01-S-28SC-U-01-S-29 MC MC SC-U-01-S-32 MC SC-U-01-S-39 MC Malone Street 36 K-3 1a Public 4.3 30 1.3 SC-U-01-S-38 MC SC-U-01-S-37 MC MC= Montgomery County, PG= Prince George's DC=District of Columbia 1a= Water Quantity, 1b= quantity & Quality, 1c= quality **Total does not include existing SWM facility acreage Table 6. Upper Sligo Creek: Candidate Stormwater Retro Candidate Stormwater Sligo Creek: 6. Upper Table

20 Figure 7a - Proposed Stormwater Retrofi t Project Photo - Wheaton Library Full Name: Wheaton Regional Public Library (Demonstration Site) Project No.: SC-U-01-S-1 ADC Map Book Location: 30 G-13 Approximate Associated 3.0 Drainage Area (acres): Approximate 75% 2.3 ac Imperviousness: General Description: Green Roof, Parking Lot Bioretention, Bioswale & Tree Boxes

Figure 7b - Proposed Stormwater Retrofi t Project Photo - Colt Terrace Full Name: Colt Terrace/Daffodil Lane Project No.: SC-U-01-S-4 ADC Map Book Location: 30 K-13 Approximate Associated 29.0 ac. Drainage Area (acres): Approximate 20% 5.8 ac. Imperviousness: General Description: Off-Line ED Wetland

21 Figure 7c - Proposed Stormwater Retrofi t Project Photo - Sligo Middle School Full Name: Sligo Middle School Project No.: SC-U-01-S-19 ADC Map Book Location: 36 K-4 Approximate Associated 7.9 ac Drainage Area (acres): Approximate 70% 5.5 ac. Imperviousness: General Description: Parking Lot Bioretention

Figure 7d - Proposed Stormwater Retrofi t Project Photo - Dennis Ave. Median Full Name: Dennis Ave. Median Project No.: SC-U-01-S-20 ADC Map Book Location: 37 A-4; 37 B-4 Approximate Associated 5.1 ac. Drainage Area (acres): Approximate 50% 2.6 ac. Imperviousness: General Description: Ex. Median Strip Conversion to LID ‘Green Street’

22 Figure 7e - Proposed Stormwater Retrofi t Project Photo - Capital Beltway Full Name: Capital Beltway East Outer Loop (~1,700 LF) Project No.: SC-U-01-S-24 ADC Map Book Location: 36 K-6; 37 A-6 Approximate Associated 5.9 ac. Drainage Area (acres): Approximate 90% 5.3 ac. Imperviousness: General Description: Off-Line ED Wetland

Figure 7f - Proposed Stormwater Retrofi t Project Photo - Holy Cross Hospital Full Name: Holy Cross Hospital Parking Lots Project No.: SC-U-01-S-25 ADC Map Book Location: 36 K-6 Approximate Associated 2.0 ac. Drainage Area (acres): Approximate 80% 1.6 ac. Imperviousness: General Description: Bioretention and Tree Boxes

23 Figure 8 - Upper Sligo Creek Candidate Stream Restoration Sites

24 Project Ranking Project Score (pts) 720,000 74 Medium 150,000 64 Low 510,000 64 Low 360,000 62 Low Cost ($) Estimated ) nt ~2, total ( total) stabilization Removal (2)) Creation ~500 LF Streambank General Description In-stream Pool Habitat 700 LF) and Vernal Pool Enhancement/Creation (-3, Removal (1) and Vernal Pool Enhancement, Fish Blockage 1200 LF) (and Fish Blockage Stream Channel Morphology (~ Stream Channel Morphology (~ (ft) Length Approx Total 6,300 $3,740,000 Ownership Type1 Project 37 A-7 1b Public 500 37 A-2 1a, 1c, 1d Public/Private 1,200 Location 36 J-1;36 K-1 1a,1d Public 2,400 37 A-7;37 A-8 1a Public/Private 1,000 ~1,000LF Stream Daylighting 2,000,000 61 Low ADC Map Book (Lower) (Upper) Facility) Tributary Breewood Local Park Upper Sligo Mainstem (Above Univ. Blvd SWM Woodside Park Tributary Woodside Park Tributary Project ID Jurisdiction Name SC-U-02-SR-2 MC Colt Terrace Tributary 30 K-13 1b, 1c, 1d Public 1,200 SC-U-02-SR-5 MC SC-U-02-SR-4 MC SC-U-02-SR-1 MC SC-U-02-SR-3 MC 1a= Channel Morphology, 1b= In-Stream Habitat/Bank Stabilization, 1c= Fish Blockage Removal, 1d= Vernal Pool Creation/Enhanceme MC= Montgomery County, PG= Prince George's DC=District of Columbia 1 Table 7. Upper Sligo Creek: Candidate Stream Restoration Projects Candidate Stream Sligo Creek: 7. Upper Table

25 Figure 9a - Candidate Stream Restoration Photo - Upper Sligo Mainstem Full Name: Upper Sligo Mainstem (Above Univ. Blvd SWM Facility) Project No.: SC-U-02-SR-1 ADC Map Book Location: 36 J-1; 36 K-1

Approximate Length (ft): 2,400

General Description: Stream Channel Morphology (~700 LF) and Vernal Pool En- hancement/Creation (~3, total)

Figure 9b - Candidate Stream Restoration Photo - Breewood Tributary Full Name: Breewood Local Park Tributary Project No.: SC-U-02-SR-3 ADC Map Book Location: 37 A-2

Approximate Length (ft): 1,200

General Description: Stream Channel Morphology (~1,200 LF), Fish Blockage Re- moval (2) and Vernal Pool Enhancement/Creation (~2, total)

26 Figure 10 - Upper Sligo Creek Candidate Wetland Restoration Sites

27 Project Ranking Project Score (pts) nt 500 83 Medium 1,000 75 Medium 1,000 711,000 Medium 76 Medium 1,000 85 High Cost ($) Estimated Board (~2, total) Vernal Pool Vernal Pool Area Vernal Pool Area Vernal Pool Area Enhancement of Ex. Enhancement of Ex. Enhancement of Ex. Enhancement of Ex. Vernal Pool Area Via General Description Concrete Weir w/ Drop Enhancement/Creation 0.5 $4,500 Approx Acre (ac) Total Ownership Type1 Project Book 36 J-1 1d Public 0.1 36 K-1 1d Public 0.1 36 K-1 1d Public 0.1 36 K-1 1d37 A-2 1a, 1c, 1d Public/Private Public 0.1 0.1 Location ADC Map Sligo Sligo Area #2 NCPPC Drive/M- Area # 1 Tributary Sligo/Colt Channing Biker Trail Breewood Mainstem- Mainstem- Local Park Terr- Hiker WSSC ROW WSSC ROW Project ID Jurisdiction Name SC-U-03-W-4 MC SC-U-03-W-1 MC SC-U-03-W-3 MC SC-U-03-W-5 MC SC-U-03-W-2 MC 1a= Channel Morphology, 1b= In-Stream Habitat/Bank Stabilization, 1c= Fish Blockage Removal, 1d= Vernal Pool Creation/Enhanceme MC= Montgomery County, PG= Prince George's DC=District of Columbia 1 Table 8. Upper Sligo Creek: Candidate Wetland Restoration Projects Wetland Candidate Sligo Creek: 8. Upper Table

28 Figure 11a - Candidate Wetland Restoration Photo - Channing Drive Full Name: Channing Drive/M-NCPPC Project No.: SC-U-03-W-1 ADC Map Book Location: 36 J-1

Approximate Length (ft): NA

General Description: Enhancement of Ex. Vernal Pool Area Via Manual Excava- tion to Deepen and Expand Pool Size

Figure 11b - Candidate Wetland Restoration Photo - Sligo/Colt Terrace Full Name: Sligo/Colt Terr.- Hiker Biker Trail Project No.: SC-U-03-W-4 ADC Map Book Location: 36 K-1

Approximate Length (ft): NA

General Description: Enhancement of Ex. Vernal Pool Area Via Concrete Weir w/Drop Board

29 Figure 12 - Candidate Fish Blockage Removal/Modifi cation Projects

30 Table 9. Upper Sligo Creek: Candidate Fish Blockage Removal/Modifi cation Projects Approx ADC Map Book Project Upstream Estimated Project Project Project ID Jurisdiction Name Ownership General Description Location Type1 Length Cost ($) Score (pts) Ranking Open (ft)

Complete- ~15 in. High. Install Sligo Mainstem- Univ. SC-U-04-F-1 MC 36 K-2 1b Public 700.0 Downstream Riffle-Grade 150,000 69 Medium Blvd Culvert Control

Sligo Mainstem- Log Partial- ~ 6 in. High. Deepen SC-U-04-F-2 MC Drop above Flora Lane 36 K-6 1b Public 9,000.0 1,000 67 Medium Ex. Notch In Top Log Trib. Sligo Mainstem- Log Partial-~6 in. High. Remove SC-U-04-F-3 MC Drop ~300 ft above 37 B-7 1a Public 2,100.0 1,000 65 Medium Top Log & Notch Lower Log Brunett Ave Complete- ~18 in. High. Sligo Mainstem- Log SC-U-04-F-4 MC 37 B-7 1a Public 400.0 Remove Both Logs and 15,000 74 Medium Drop @ Brunett Ave Replace w/ RockVanes

Wheaton Branch- Log Partial- ~ 6 in. High. Deepen SC-U-04-F-5 MC 36 K-4 1b Public 1,300.0 1,000 64 Low Drop Ex. Notch In Top Log

Flora Lane Tributary/Hiker Replace Ex. Twin 42" CMP's w/ SC-U-04-F-6 MC 36 K-6 1a Public 700.0 15,000 62 Low BikerTrail Culvert Foot Bridge 31 Fish Blockage Removal (2) Breewood Local Park SC-U-04-F-7 MC 37 A-2 1a, 1c, 1d Public/Private 900.0 (and Stream Channel 150,000 61 Low Tributary Morphology (~ 1,200 LF))

In-stream Pool Habitat Enhancement, Fish Blockage SC-U-04-F-8 MC Colt Terrace Tributary 30 K-13 1b, 1c, 1d Public 1,200.0 150,000 64 Low Removal (1) and Vernal Pool Creation (~2, total) Total 15,100.0 $483,000 MC= Montgomery County, PG= Prince George's County, DC=District of Columbia 11a= Removal, 1b= Modification Figure 13a - Candidate Fish Blockage Removal Site Photo - Sligo Mainstem Full Name: Sligo Mainstem- Univ. Blvd Culvert Project No.: SC-U-04-F-1 ADC Map Book Location: 36 K-2 Approximate Upstream 700 Length Open (ft): General Description: Complete- ~15 in. High. Install Downstream Riffl e-Grade Control

Figure 13b - Candidate Fish Blockage Removal Site Photo - Sligo Mainstem (2) Full Name: Sligo Mainstem- Log Drop @ Brunett Ave Project No.: SC-U-04-F-4 ADC Map Book Location: 37 B-7 Approximate Upstream 400 Length Open (ft): General Description: Complete- ~18 in. High. Remove Both Logs and Replace w/ RockVanes

32 Figure 14 - Upper Sligo Creek Candidate Riparian Restoration Sites

33 Table 10. Upper Sligo Creek: Candidate Riparian Reforestation, Meadow Creation, Street Tree and Invasive Plant Management Projects Approx ADC Map Book Project Estimated Project Project Project ID Jurisdiction Name Ownership Acreage General Description Location Type1 Cost ($) Score (pts) Ranking (ac)

Reforestation of Ex. Grass SC-U-05-R-1 MC Colt Terrace Area 30 K-13 1a/1b Public 0.3 2,700 68 Medium Area

Ladd Street/M-NCPPC SC-U-05-R-2 MC 36 K-1 1d Public 0.2 Invasives-Bamboo 500 75 Medium Foot Bridge

Reforestation of Ex. Grass SC-U-05-R-3 MC Windham Lane Area 36 K-3 1b Public 0.1 900 66 Medium Area

Sligo Mainstem - Forest SC-U-05-R-4 MC 36 K-5 1b Public 0.7 Riparian Buffer-Understory 6,300 74 Medium Glenn Road Area

SC-U-05-R-5 MC Sligo Soccer Field Area 36 K-6 1c Public 0.2 Wildflower Meadow 1,000 74 Medium

Invasives-Japanese Bindweed, SC-U-05-R-6 MC Wheaton Branch 36 K-4 1d Public 0.2 500 67 Medium English Ivy

34 Invasives-Stilt Grass, English SC-U-05-R-7 MC Woodside Park Tributary 37 A-7 1d Public 0.2 Ivy, Japanese Bindweed, 500 71 Medium Porcelainberry Total 1.9 $12,400

1MC= Montgomery County, PG= Prince George's County, DC=District of Columbia Figure 15a - Candidate Riparian Restoration Photo - Colt Terrace Area Full Name: Colt Terrace Area Project No.: SC-U-05-R-1 ADC Map Book Location: 30 K-13

Approximate Acreage: 0.3 General Description: Reforestation of Ex. Grass Area

Figure 15b - Candidate Riparian Restoration Photo - Ladd Street Full Name: Ladd Street/M-NCPPC Foot Bridge Project No.: SC-U-05-R-2 ADC Map Book Location: 36 K-1 Approximate Upstream 0.2 Length Open (ft): General Description: Invasives-Bamboo Eradication and Reforestation

35 Figure 16 - Upper Sligo Creek: Trash Reduction Projects

36 Table 11. Upper Sligo Creek: Candidate Trash Reduction Projects Approx ADC Map Book Project Estimated Project Project ID Jurisdiction Name Ownership Length General Description Project Ranking Location Type1 Cost ($) Score (pts) (mi)

Georgia Ave (Arcola Ave SC-U-06-T-1 MC 30 H-13, 36 K-9 1a Public 3.2 Street Sweeping (Weekly) 4,186 78 Medium to Spring Street)

Capital Beltway (I-495- 36 J-6,7;37A-6, B- Road Shoulder Cleaning SC-U-06-T-2 MC Georgia Ave-Colesville 1b Public 1.2 1,559 75 Medium 7 (Weekly) Road)

University Blvd (Georgia SC-U-06-T-3 MC 36 H-1, 37 C-5 1a Public 2.7 Street Sweeping (Weekly) 3,447 78 Medium Ave to Colesville Road)

Flora Lane Tributary- Trash Fence/Trash Boom or SC-U-06-T-4 MC Columbia Blvd SD Outfall 36 J-6,7 1c, 1d Public NA Equivalent; SD Inlet Grates on 7,000 81 Medium Area Select Side Streets; Outreach

Trash Fence/Trash Boom or SC-U-06-T-5 MC Woodside Park Tributary 37 A-7 1c Public NA 2,000 70 Medium Equivalent

Total 7.1 $18,192

1MC= Montgomery County, PG= Prince George's County, DC=District of Columbia 11a= Street Sweeping, 1b= Manual/Mecahnical Removal, 1c= Structural, 1d=Outreach/Education 37 Figure 17a - Trash Reduction Site Photo - University Blvd Full Name: University Blvd (Georgia Ave to Colesville Rd) Project No.: SC-U-06-T-3 36 G-1; 36 H-1; 36 J-1; 36 J-2; 36 J K-2; 37 A-2; ADC Map Book Location: 37 B-2; 37 B-3; 37 B-4; 37 C-4; 37 C-5

Approximate Length (mi): 2.7

General Description: Street Sweeping (Weekly)

38 V. Middle Sligo - Candidate Restoration Projects (w/ representative photos)

39 Table 12. Middle Sligo Creek - Impervious Surfaces

Major Tributaries

Associated Acreage Category (ac) Long Branch

1. Roads (mi/ac) 81.4mi/270.9 ac 22.5 mi/82.1 ac a. State/Federal 8.4 mi/58.8 ac 2.8 mi/26.5 ac b. Local 73.1 mi/212.1 ac 19.7 mi/55.6 ac 2. Parking Lots: 133.1 ac 34.7 ac a. Public/Institutional 66.7 ac 23.0 ac b. Private 66.4 ac 11.7 ac 3. Roofs 337.9 ac 91.5 ac a. Public/Institutional 71.0 ac 16.8 ac b. Private (Non-Single Family) 59.5 ac 13.2 ac c. Single Family Homes 207.4 ac 61.5 ac 4. Other a. Single Family Driveways* 105.0 ac 32.8 ac b. Sidewalks** 35.4 ac 9.6 ac Total 882.3 ac 250.7 ac Avg. Percent Imperviousness (%) 34% 31% No. of Single Family Homes 7,501 2,346 Total D.A. = 2,610 ac 799 ac

*Driveways area assumption: Average Driveway = 600 sq. ft.

**Sidewalks area assumptions: Width equal to 4 ft. Sidewalks run length of roads At least one side of road has sidewalk

40 Figure 18 - Middle Sligo Candidate Stormwater Retrofi t Sites

41 Table 13. Middle Sligo Creek: Candidate Stormwater Retrofi t Projects

ADC Map Approx. Project Project Approx Estimated Project Project ID Jurisdiction Name Book Ownership Impervious General Description Score Type1 D.A. (ac) Cost ($) Ranking Location (pts) % (ac.) Silver Spring Fire Green Roof & Parking Lot SC-M-01-S-1 MC 37 D-5 1c Public 1.3 55 0.7 415,904 78 Medium Station 19 Bioretention

US RTE 29 @ Capital 37 B-6; 37 SC-M-01-S-2 MC Beltway Interchange 1c Public 8.3 80.0 6.6 Bioretention 664,000 72 Medium C-6 (~1,800 LF)

University Blvd/Capital 37 D-5; 37 SC-M-01-S-3 MC 1c Public 2.5 98.0 2.5 Bioretention in Cloverleaf 245,000 69 Medium Beltway Cloverleaf D-6

Green Roof, Biorentention, SC-M-01-S-4 MC Silver Spring Center 37 A-9 1c Public 1.8 90 1.6 Tree Box, Pervious Pavement, 731,808 74 Medium and Planter Box Green Roof & Parking Lot SC-M-01-S-5 MC Silver Spring Library 37 A-9 1c Public 3.0 60.0 1.8 668,856 71 Medium Bioretention SC-M-01-S-6 MC Bennington Drive 37 B-8 1c Public 4.6 35.0 1.6 Bioretention in Median 180,000 58 Low International Middle Athletic Field - Underground SC-M-01-S-7 MC 37 C-8 1c Public 77.1 45.0 34.7 400,000 65 Medium School-Wayne Ave. Pipe Storage Green Roof, Tree Box &

42 SC-M-01-S-8 MC Highland View ES 37 D-8 1b Public 2.4 80.0 1.9 2,275,424 68 Medium Parking Lot Bioretention

Parking Lot Bioretention, Tree SC-M-01-S-9 MC Oakview ES 37 E-8 1b Public 5.1 60.0 3.1 Box, Downspout Disconnection 306,000 71 Medium & Rain Gardens

Flower Avenue Parking Lot Bioretention & SC-M-01-S-10 MC 37 E-9 1b Private 13.1 90.0 11.8 700,000 70 Medium Shopping Center Underground Pipe Storage Dry Pond Conversion to Sand SC-M-01-S-11 MC Pickwick Village 37 E-8 1c Private 8.1 70.0 5.7 30,000 61 Low Filter System Green Roof & Bioretention SC-M-01-S-12 MC Long Branch Library 37 E-9 1b Public 2.2 68 1.5 801,808 80 Medium Facility Long Branch/Garland SC-M-01-S-13 MC 37 E-9 1b Public 15.1 60.0 9.1 Underground Pipe Storage 100,000 58 Low Park Long Branch Parking Lot Porous Pavement SC-M-01-S-14 MC 37 E-9 1c Public 3.4 80.0 2.7 272,000 85 High Community Center & Tree Boxes Conversion of Ex.Oil/Grit 37 E-9; 37 Separator to Sand Filter, SC-M-01-S-15 MC Rolling Terrace ES 1b Public 4.4 80.0 3.5 3,057,232 77 Medium F-9 Parking Lot Bioretention & Green Roof Seventh Day Adventist SC-M-01-S-16 MC 37 F-10 1c Private 5.7 80.0 4.6 Parking Lot Bioretention 456,000 63 Low ES Table 13. Middle Sligo Creek: Candidate Stormwater Retrofi t Projects (Continued)

ADC Map Approx. Project Project Approx Estimated Project Project ID Jurisdiction Name Book Ownership Impervious General Description Score Type1 D.A. (ac) Cost ($) Ranking Location (pts) % (ac.)

SC-M-01-S-17 MC Takoma Academy 37 F-10 1c Private 9.2 80.0 7.4 Parking Lot Bioretention 736,000 71 Medium Caroll Ave-Service SC-M-01-S-18 MC Road (Merrimac Dr- 37 F-10 1c Public 0.9 98.0 0.9 Green Street LID/Bioswale 88,200 57 Low Chester St) Columbia Union Parking Lot Bioretention & SC-M-01-S-19 MC 37 E-11 1c Private 2.1 98.0 2.1 205,800 71 Medium College Porous Pavement

Parking Lot Bioretention, Tree Washington Adventist SC-M-01-S-20 MC 37 E-11 1c Private 3.8 90.0 3.4 Boxes, Downspout 342,000 63 Low Hospital Disconnection & Gully Control

Green Roof & Porous SC-M-01-S-21 MC Takoma Branch ES 37 C-12 1b Public 2.8 90.0 2.5 1,360,664 70 Medium Pavement Off-Line ED Wetland, Parking Takoma Park Middle SC-M-01-S-22 MC 37 C-11 1b Public 8.9 70.0 6.2 Lot Bioretention, Tree Boxes, 623,000 74 Medium School Downspout Disconnection WMATA-Takoma Parking Lot Bioretention & SC-M-01-S-23 DC Metro Station Parking 37 C-13 1c Public 3.7 90.0 3.3 333,000 67 Medium Tree Boxes Lot & Bus Lanes 43 Takoma Park Rec SC-M-01-S-24 CTP 37 G-12 1b Public 0.7 95.0 0.7 Bioretention Cell 65,550 67 Medium Center

SC-M-01-S-25 CTP Various City Projects Data Collection in Progress #N/A #N/A

SC-M-01-S-26 MC YMCA Parking Lot 1c Private 1.3 98 1.2 Parking Lot Bioretention 122,500 67 Medium

Green Street LID/Bioswale & Hastings Drive 'Green Bioretention (in Granville SC-M-01-S-27 MC 1c Public 9.6 50 4.8 480,000 66 Medium Street' Dr/Hastings Dr. Open Space Area) Road and Lawn Area SC-M-01-S-28 CTP Cleveland Avenue 6 B-12 1c Public 1.3 30 0.39 Bioretention and Underground 100,000 83 High Storage Total 202.3 118.8 $15,760,746 MC= Montgomery County, PG= Prince George's County, DC=District of Columbia, CTP= City of Takoma Park 11a= Water Quantity, 1b= Water quantity & Quality, 1c= Water quality Figure 19a - Proposed Stormwater Retrofi t Project Photo - Highland View ES Full Name: Highland View ES Project No.: SC-M-01-S-8 ADC Map Book Location: 37 D-8 Approximate Associated 2.4 Drainage Area (acres): Approximate 80% 1.9 ac. Imperviousness: General Description: Green Roof, Tree Box & Parking Lot Bioretention

Figure 19b - Proposed Stormwater Retrofi t Project Photo - Flower Ave Shopping Center Full Name: Flower Avenue Shopping Center Project No.: SC-M-01-S-10 ADC Map Book Location: 37 E-9 Approximate Associated 13.1 Drainage Area (acres): Approximate 90% 11.8 ac. Imperviousness: General Description: Parking Lot Bioretention & Underground Pipe Storage

44 Figure 19c - Proposed Stormwater Retrofi t Project Photo - Washington Adventist Hosp. Full Name: Washington Adventist Hospital Project No.: SC-M-01-S-20 ADC Map Book Location: 37 E-11 Approximate Associated 3.8 Drainage Area (acres): Approximate 90% 3.4 ac. Imperviousness: General Description: Parking Lot Bioretention, Tree Boxes, Downspout Disconnection & Gully Control

Figure 19d - Proposed Stormwater Retrofi t Project Photo - Takoma Metro Station Full Name: WMATA-Takoma Metro Station Parking Lot & Bus Lanes Project No.: SC-M-01-S-23 ADC Map Book Location: 37 C-13 Approximate Associated 3.7 Drainage Area (acres): Approximate 90% 3.3 ac. Imperviousness: General Description: Parking Lot Bioretention & Tree Boxes

45 Figure 20 - Middle Sligo Creek Candidate Stream Restoration Sites

46 Project Ranking Project Score (pts) 90,000 63 Low 390,000 73 Medium 300,000 67 Medium Cost ($) Estimated nt (~2000 LF) Erosion Control In-Stream Habitat General Description Enhancement, and Gully Stream Channel Morphology Enhancement (~1000 LF) and Fish Blockage Modification (1) In-stream Riffle & Pool Habitat Approx Length (ft) Total 3,300 $780,000 1b,1c Public 1,000 1a, 1b Public 2,000 Project Type Ownership C-8 37 C-8 1a, 1b, 1d Public 300 37 D-11 Location ADC Map Book 37 B-7; B-8;37 37 C-10; C-11; y Name Dr. Area) @ Sligo Creek Park Middle Sligo Mainstem (Worth Ave. to Pershing Greenbrier Drive Tributar 1 Jurisdiction Project ID SC-M-02-SR-3 MC Parkside Road Tributary SC-M-02-SR-2 MC SC-M-02-SR-1 MC 1a= Channel Morphology, 1b= In-Stream Habitat/Bank Stabilization, 1c= Fish Blockage Removal, 1d= Vernal Pool Creation/Enhanceme MC= Montgomery County, PG= Prince George's DC=District of Columbia 1 Table 14. Middle Sligo Creek: Candidate Stream Restoration Projects Restoration Projects Candidate Stream 14. Middle Sligo Creek: Table

47 Figure 21 - Candidate Stream Restoration Photo - Greenbrier Drive Tributary Full Name: Greenbrier Drive Tributary @ Sligo Creek Park Project No.: SC-M-02-SR-2 ADC Map Book Location: 37 C-8

Approximate Length (ft): 300

General Description: In-stream Riffl e & Pool Habitat Enhancement, Gully Erosion Control and Wetland Creation (~0.1 ac)

48 Figure 22 - Middle Sligo Creek Candidate Wetland Restoration Sites

49 Project Ranking Project Score (pts) 10,000 81 Medium Cost ($) Estimated nt Vernal Pool Area via Understory Plantings General Description Excavation, Fencing and Enhancement of Ex. 150 LF 0.25 $15,000 Approx. Acre (ac) Total Project Type Ownership Book 37 C-8 1d Public 0.15 37 C-8 1a, 1b, 1d Public 0.10 Wetland Creation (~0.1 ac) 5,000 64 Low Location ADC Map Name Creek Park (Three Oaks Dr- Greenbrier Drive Trail Vernal Pool Sligo Creek Foot Tributary @ Sligo Schuyler Rd Area) 1 Jurisdiction Project ID SC-M-03-W-2 MC SC-M-02-W-1 MC 1a= Channel Morphology, 1b= In-Stream Habitat/Bank Stabilization, 1c= Fish Blockage Removal, 1d= Vernal Pool Creation/Enhanceme MC= Montgomery County, PG= Prince George's DC=District of Columbia 1 Table 15. Middle Sligo Creek: Candidate Wetland Restoration Projects Restoration Projects Wetland Candidate 15. Middle Sligo Creek: Table

50 Figure 23 - Candidate Wetland Restoration Photo - Sligo Creek Trail Vernal Pool Full Name: Sligo Creek Foot Trail Vernal Pool (Three Oaks Dr-Schuyler Rd Area) Project No.: SC-M-03-W-2 ADC Map Book Location: 37 C-8

Approximate Length (ft): NA

General Description: Enhancement of Ex. 150 LF Vernal Pool Area via Excavation, Fencing and Understory Plantings

51 Figure 24 - Candidate Fish Blockage Removal/Modifi cation Projects

52 Table 16. Middle Sligo Creek: Candidate Fish Blockage Removal/Modifi cation Projects

Approx. ADC Map Book Project Estimated Project Project Project ID Jurisdiction Name Ownership Upstream General Description Location Type1 Cost ($) Score (pts) Ranking Length (ft)

Sligo Mainstem- Log Drop Partial- ~8 in. High. Deepen SC-M-04-F-1 MC ~500 ft below Colesville 37 B-7 1b Public 2,000.0 500 73 Medium Ex. Notch In Top Log Road

Sligo Mainstem - 12 in. Partial- ~6 in. High. Install SC-M-04-F-2 MC DIP ~100 LF above 37 C-8 1b Public 600.0 8,000 69 Medium Rock Vanes Across Stream Bennington Dr. Trib. Sligo Mainstem- WSSC Complete- ~30 in. High. Install SC-M-04-F-3 MC Sewer Line ~500 ft Below 37 C-9 1b Public 3,700.0 375,000 70 Medium Riffle Grade Control Wayne Ave Sligo Mainstem- 12 in Partial- ~6 in. High. Install SC-M-04-F-4 MC DIP ~800 ft Below Piney 37 D-10 1b Public 2,200.0 8,000 65 Medium Rock Vanes Across Stream Branch Road

Devon Road - WSSC Complete- ~20 in. High. Riffle SC-M-04-F-5 MC 37 E-12 1b Public 3,000.0 255,000 68 Medium Sewer Line Grade Control Sligo Mainstem- Historic Complete- ~24 in. High. Install SC-M-04-F-6 MC Weir~ 200 ft Maple Ave 37 E-12 1b Public 4,500.0 30,000 56 Low 53 Fish Ladder Ave Complete- ~12 in. High. Install Long Branch - Fortson SC-M-04-F-7 MC 37 E-10 1b Public 2,000.0 Downstream Riffle-Grade 150,000 61 Low Street Control Complete- ~27 in. High. Install Long Branch- Piney SC-M-04-F-8 MC 37 E-9 1b Public 4,500.0 Downstream Riffle-Grade 337,500 59 Low Branch Road Culvert Control Total 22,500.0 $1,164,000

1MC= Montgomery County, PG= Prince George's County, DC=District of Columbia

11a= Removal, 1b= Modification Figure 25a - Candidate Fish Blockage Removal Site Photo - Sligo Mainstem Full Name: Sligo Mainstem- WSSC Sewer Line ~500 ft Below Wayne Ave Project No.: SC-M-04-F-3 ADC Map Book Location: 37 C-9 Approximate Upstream 3,700 Length Open (ft): General Description: Complete- ~30 in. High. Install Riffl e Grade Control

Figure 25b - Candidate Fish Blockage Removal Site Photo - Long Branch Full Name: Long Branch- Piney Branch Road Culvert Project No.: SC-M-04-F-8 ADC Map Book Location: 37 E-9 Approximate Upstream 4,500 Length Open (ft): General Description: Complete- `27 in. High. Install Downstream Riffl e-Grade Control

54 Figure 26 - Middle Sligo Creek Candidate Riparian Restoration Projects

55 Table 17. Middle Sligo Creek: Candidate Riparian Reforestation, Meadow Creation, Street Tree and Invasive Plant Management Projects

Approx ADC Map Book Project Estimated Project Project Project ID Jurisdiction1 Name Ownership Acreage General Description Location Type2 Cost ($) Score (pts) Ranking (ac)

Bennington Drive SC-M-05-R-1 MC 37 B-8 1d Public 0.1 Invasives- Bamboo 500 70 Medium Tributary Area

Sligo Creek Foot Trail SC-M-05-R-2 MC (Three Oaks Dr-Schuyler 37 C-8 1d Public 0.2 Invasives- English Ivy 500 75 Medium Rd Area)

Sligo Mainstem - Park SC-M-05-R-3 MC 37 D-10; 37 D-11 1d Public 0.3 Invasives- English Ivy 500 80 Medium Valley Road Area 56 Invasives- English Ivy, Sligo Mainstem - Carroll SC-M-05-R-4 MC 37 F-11 1d Public 0.5 Bamboo, Porcelainberry, 500 76 Medium Ave-Garland Ave Japanese Bindweed Long Branch-East Wayne Invasives- Management & SC-M-05-R-5 MC 37 E-8 1b, 1d Public 0.2 500 78 Medium Park Riparian Reforestation Long Branch-Community Invasives- Management & SC-M-05-R-6 MC 37 E-9 1b, 1d Public 0.2 500 80 Medium Center Area Riparian Reforestation Total 1.5 $3,000 1MC= Montgomery County, PG= Prince George's County, DC=District of Columbia 21a=Upland Reforestation, 1b= Riparian Reforestation, 1c= Meadow Creation,1d= Invasive Plant Management Figure 27 - Candidate Riparian Restoration Photo - East Wayne Park Full Name: Long Branch-East Wayne Park Project No.: SC-M-05-R-5 ADC Map Book Location: 37 E-8

Approximate Acreage (ac): 0.2

General Description: Invasives Management & Riparian Reforestation

57 Figure 28 - Trash Reduction Projects

58 Table 18. Middle Sligo Creek: Candidate Trash Reduction Projects

Approx ADC Map Book Project Estimated Project Project Project ID Jurisdiction1 Name Ownership Length General Description Location Type2 Cost ($) Score (pts) Ranking (mi) Capital Beltway (I-495- Road Shoulder Cleaning SC-M-06-T-1 MC Colesville Road-University 37 C-6; 37 D-6 1b Public 0.6 739 75 Medium (Weekly) Blvd)

University Blvd East SC-M-06-T-2 MC (Colesville Road to New See Map Page 37 1a Public 2.7 Street Sweeping (Weekly) 3,447 78 Medium Hampshire Avenue)

Piney Branch Road (Sligo Street Sweeping (Weekly), SD 37 D-9; 37 E-9; SC-M-06-T-3 MC Creek Pkwy to University 1a,1c,1d Public 0.8 Inlet Grates or Inserts @ 3,485 75 Medium 37 F-9 Blvd) Select Inlets; Outreach

37 C-13;37 D-13; Carroll Avenue (University 37 D-12; 37 E-12; SC-M-06-T-4 MC 1c, 1d Public 1.7 Street Sweeping (Weekly) 2,216 77 Medium Blvd to Eastern Ave) 37 E-11; 37 F-11; 37 F-10

Street Sweeping (Weekly), SD Eastern Avenue (Laurel 37 B-12;37 B-13; SC-M-06-T-5 DC 1a,1c,1d Public 0.8 Inlet Grates or Inserts @ 3,485 75 Medium Ave to 6th St) 37 C-13 59 Select Inlets; Outreach

Total 6.4 $13,371

1MC= Montgomery County, PG= Prince George's County, DC=District of Columbia Figure 29 - Trash Reduction Site Photo - Piney Branch Road Full Name: Piney Branch Road Project No.: SC-M-06-T-3 ADC Map Book Location: 37 D-9; 37 E-9; 37 F-9

Approximate Length (ft): 4,000

General Description: Street Sweeping (Weekly), SD Inlet Grates or Inserts @ Select Inlets; Outreach

60 VI. Lower Sligo - Candidate Restoration Projects (w/ representative photos)

61 Table 19. Lower Sligo Creek - Impervious Surfaces

Major Tributaries Minor Tributaries

Associated Category Acreage (ac) Raydale Road Takoma Branch 1. Roads (mi/ac) 40.2 mi/176.5 ac 23.6 mi/91.9 ac 1.8 mi/6.4 ac a. State/Federal 5.2 mi/39.9 ac 1.4 mi/12.1 ac 0.0 mi/0.0 ac b. Local 35.0 mi/136.6 ac 22.2 mi/79.8 ac 1.8 mi/6.4 ac 2. Parking Lots: 103.1 ac 55.7 ac 1.4 ac a. Public/Institutional 49.4 ac 16.1 ac 0.2 ac b. Private 53.7 ac 39.6 ac 1.3 ac 3. Roofs 181.7 ac 108.9 ac 7.3 ac a. Public/Institutional 43.5 ac 29.3 ac 0.9 ac b. Private (Non-Single Family) 34.1 ac 20.0 ac 0.8 ac c. Single Family Homes 104.1 ac 59.6 ac 5.6 ac 4. Other a. Single Family Driveways* 58.5 ac 30.7 ac 0.9 ac b. Sidewalks** 17 ac 10.8 ac 2.9 ac Total 536.7 ac 298.0 ac 18.9 ac Avg. Percent Imperviousness (%) 35% 37% 29% No. of Single Family Homes 4,176 2,196 211 Total D.A. = 1525 ac 806 ac 65 ac

62 Figure 30 - Lower Sligo Candidate Stormwater Retrofi t Sites

63 Table 20. Lower Sligo Creek: Candidate Stormwater Retrofi t Projects Approx. Project ADC Map Book Project Approx Impervious Estimated Project Project ID Jurisdiction Name Ownership General Description Score Location Type1 D.A. (ac) Cost ($) Ranking %(ac) (pts)

Chillum Place (Sligo Mill SC-L-01-S-1 DC Road to Underwood 42 C-1 1c Public 20.0 85 17.0 Green Street LID and Tree 1,700,000 76 Medium Street) Boxes Parking Lot and Lawn Area SC-L-01-S-2 DC Jackie Robinson Center 43 D-2 1c Public 1.0 98 1.0 100,940 67 Medium Biorentention

Eastern Avenue (Laurel SC-L-01-S-3 DC 42 C-1, E-2 1c Public 1.0 90 0.9 Green Street LID and Curbside 90,000 58 Low Street to 6th Street) Planters Targeted Riversmart Area 10 Hampshire Knolls SC-L-01-S-4 DC 43 C-1, E-2 1c Private 17.0 30 5.1 Homes (Note: Ex. # SF 50,000 79 Medium Neighborhood Homes=74), Rooftop and Open Space Area SC-L-01-S-5 PG Chillum Terrace Apts. 11 F-2 1c Private 0.6 25.0 0.1 9,375 69 Medium Rain Garden Parking Lot and Lawn Area SC-L-01-S-6 PG Chillum Terrace Apts. 11 F-2 1c Private 0.8 62.5 0.5 48,000 63 Low Biorentention Bioretention/Trash Train on SC-L-01-S-7 PG Redtop Road 11 G-1 1c Public 10.0 50.0 5.0 112,500 71 Medium Each Side of Road

SC-L-01-S-8 PG Takoma Park Plaza 11 E-1 1c Private 3.1 98.0 3.1 204,800 64 Low Parking Lot Bioretention Chillum Manor Road and

64 SC-L-01-S-9 PG Knollbrook Drive 'Green 11 G-1, H-1 1c Public 8.0 21.1 1.7 Bioretention, Curbside Street 167,000 65 Medium Street' Planters and Tree Boxes Green Roof and Parking SC-L-01-S-10 PG Ridgecrest ES 11 F-2 1c Public 1.7 98.0 1.7 2,255,424 66 Medium Lot/Driveway Bioretention Jehovah Witnesses SC-L-01-S-11 PG 11 F-2 1c Private 0.7 98.0 0.7 71,000 58 Low Nursing Home Bioretention and Tree Boxes Green Street LID-Curbside Raydale Road 'Green SC-L-01-S-12 PG 11 F-2 1c Public 6.2 68.0 4.2 Planters (~1,500 LF treated) 420,000 77 Medium Street' and Tree Boxes (~14) Riggs Rd (Fair Oak Ave SC-L-01-S-13 PG to E/W Highway) 'Green 11 G-1, G-2 1c Public 8.9 83.0 7.5 750,000 65 Medium Street' Green Street LID/Bioswale Riggs /Sargent Shopping SC-L-01-S-14 PG 11 G-1 1c Private 8.5 98.0 8.5 850,000 68 Medium Center Parking Lot Bioretention Green Roof and Parking Lot SC-L-01-S-15 PG Cesar Chavez ES 11 H-1 1c Public 2.9 80.0 2.3 1,623,616 68 Medium Bioretention M-NCPPC Rollingcrest SC-L-01-S-16 PG 11 G-1 1c Public 2.0 98 2.0 200,000 71 Medium Chillum Splash Park Parking Lot Bioretention St. John the Bapt de La SC-L-01-S-17 PG 11 G-2 1c Private 1.9 98 1.9 190,000 61 Low Salle Parking Lot Bioretention Total 94.4 63.2 $8,842,655 MC= Montgomery County, PG= Prince George's County, DC=District of Columbia, CTP=City of Takoma Park 11a= Water Quantity, 1b= Water quantity & Quality, 1c= Water quality Figure 31a - Proposed Stormwater Retrofi t Project Photo - Takoma Park Plaza Full Name: Takoma Park Plaza Project No.: SC-L-01-S-8 ADC Map Book Location: 11 E-1 Approximate Associated 3.1 Drainage Area (acres): Approximate 98% 3.1 ac. Imperviousness: General Description: Parking Lot Bioretention

Figure 31b - Proposed Stormwater Retrofi t Project Photo - Chillum Manor Road Full Name: Chillum Manor Road and Knollbrook Drive ‘Green Street’ Project No.: SC-L-01-S-9 ADC Map Book Location: 11 G-1; H-1 Approximate Associated 8.0 Drainage Area (acres): Approximate 21.1% 1.7 ac. Imperviousness: General Description: Bioretention, Curbside Street Planters and Tree Boxes

65 Figure 32 - Lower Sligo Creek Candidate Stream Restoration Sites

66 Project Ranking Project Score (pts) 612,000 69 Medium 252,000 67 Medium 540,000 65 Medium 396,000 71 Medium Cost ($) Estimated nt, 1e= Wetland (~1,700 LF) General Description Habitat Enhancement Blockage Removal (1) In-stream Pool Habitat Enhancement, and Fish Restoration (~700 LF) and Overbank Wetland Creation Stream Channel Morphology Stream Channel Morphology (~900 LF), and In-stream Pool Instream Habitat Enhancement Approx Length (ft) Total 5,250 $2,300,000 Ownership 1 Type Project 11 G-1 1b Public 700 11 G-1 1b, 1c, 1d Public 1,100 11 G-1 1b, 1d 1a, Public/Private 1,500 Location 12 G-1,G-2 1b Public 250 Stream Daylighting (~250 LF) 500,000 63 Low 11 G-1,G-2 1b Public 1,700 ADC Map Book Park Road Section) Manor Road Sligo Mainstem (19th Ray Road to Red Top Place to Roanoake St) Prince George's Avenue Red Top Road to Chillum Raydale Road Trib (Open Project ID Jurisdiction Name SC-L-02-SR-5 PG SC-L-02-SR-4 PG SC-L-02-SR-1 PG SC-L-02-SR-3 PG SC-L-02-SR-2 PG 1a= Channel Morphology, 1b= In-Stream Habitat/Bank Stabilization, 1c= Fish Blockage Removal, 1d= Vernal Pool Creation/Enhanceme MC= Montgomery County, PG= Prince George's DC=District of Columbia 1 Creation/Restoration Table 21. Lower Sligo Creek: Candidate Stream Restoration Projects Restoration Projects Candidate Stream Sligo Creek: 21. Lower Table

67 Figure 33a - Candidate Stream Restoration Photo - Takoma Branch Full Name: Takoma Branch (Ray Road to Red Top Road) Project No.: SC-L-02-SR-1 ADC Map Book Location: 11 G-1

Approximate Length (ft): 1,100

General Description: In-stream Pool Habitat Enhancement, Fish Blockage Removal (1) and Vernal Pool Enhancement/Creation (3, total)

Figure 33b - Candidate Stream Restoration Photo - Sligo Mainstem Full Name: Sligo Mainstem (19th Place to Roanoake St) Project No.: SC-L-02-SR-4 ADC Map Book Location: 11 G-1, G-2

Approximate Length (ft): 1,700

General Description: Instream Habitat Enhancement (~ 1,700 LF)

68 Figure 34 - Lower Sligo Creek Candidate Wetland Restoration Sites

69 Project Ranking 69 Medium 72 Medium 83 Medium (pts) Score Project 1,500 1,000 10,000 30,000 65 Medium 30,000 64 Low Cost ($) Estimated nt, 1e= Wetland total) total) acres) acres) Vernal Pool Vernal Pool General Description Wetland Creation (~0.2 Wetland Creation (~0.3 Enhancement/Creation (3, Enhancement/Creation (2, (ac) pprox Area A Total 1.0 $72,500 Ownership 1 1e Public 0.1 Vernal pool creation (~2) Type Project Book 11 G-1 1b, 1c, 1d Public 0.2 11 G-1 1a, 1b, 1d Public 0.2 Location ADC Map 13; 42 F-1 11 H-3, J-3 1e Public 0.2 11 H-2, J-2 1e Public 0.3 37 F-13, G- Road Ray Road to Sligo-WTOP Transmitter Area Road to Red Top Red Top Road to M-NCPPC Lower Wetland Creation Pepco ROW from Park/16th Avenue M-NCPPC Chillum East/West Highway Takoma Branch Ray Chillum Manor Road Project ID Jurisdiction Name SC-L-03-W-1 PG SC-L-03-W-3 PG SC-L-03-W-4 PG SC-L-03-W-2 PG SC-L-03-W-5 PG 1a= Channel Morphology, 1b= In-Stream Habitat/Bank Stabilization, 1c= Fish Blockage Removal, 1d= Vernal Pool Creation/Enhanceme MC= Montgomery County, PG= Prince George's DC=District of Columbia Creation/Restoration 1 Table 22. Lower Sligo Creek: Candidate Wetland Restoration Projects Wetland Candidate Sligo Creek: 22. Lower Table

70 Figure 35 - Candidate Wetland Restoration Photo - Ray Road

Full Name: Takoma Branch Ray Road to Red Top Road Project ID: SC-L-03-W-4 ADC Map Book Location: 11 G-1

Approximate Area (ac): 0.2

General Description: Vernal Pool Enhancement/Creation (3, total)

71 Figure 36 - Candidate Fish Blockage Removal Projects

72 Table 23. Lower Sligo Creek: Candidate Fish Blockage Removal/Modifi cation Projects

Approx. ADC Map Book Project Upstream Estimated Project Project Project ID Jurisdiction Name Ownership General Description Location Type1 Length Cost ($ Score (pts) Ranking Opened (ft)

Sligo Creek Mainstem - Complete - ~12 in. High Sheet SC-L-04-F-1 PG S0 ~700 ft. Upstream of 11 J-3 1b Public 3,000.0 Pile Weir. Install Downstream 150,000 71 Medium NW Br. confluence Riffle-Grade Control

Partial - ~4-6 in. High Sheet Sligo Creek Mainstem - Pile Weir. Modify Existing SC-L-04-F-2 PG S3 (behind Green 11 H-2 1b Public 9,000.0 75,000 71 Medium Downstream Riffle-Grade Meadows Com. Rec. Ctr.) Control

Sligo Creek Mainstem - Complete - Trapezoidal SC-L-04-F-3 PG 11 H-1 1b Public 560.0 150,000 71 Medium S5 (Riggs Road) Concrete Channel. Install a 8- 12 inch deep baseflow channel

Sligo Creek Mainstem - Complete - ~2.5 ft High. Sewer SC-L-04-F-4 PG S6 (500 ft upstream of 11 H-1 1b Public 1,023.0 Line Crossing. Install 375,000 65 Medium Riggs Road) Downstream Riffle-Grade Control

73 Sligo Creek Mainstem - Line Crossing. Install SC-L-04-F-5 PG S7 (280 ft downstream of 6 H-13 1b Public 5,463.0 Downstream Riffle-Grade 150,000 71 Medium E/W Hwy) Control Complete - ~2 ft High. Takoma Branch - Chillum Concrete Culvert. Install SC-L-04-F-6 PG 6 H-13 1b Public 2,000.0 300,000 59 Low Manor Road Culvert Downstream Riffle-Grade Control Complete - ~2.6 ft High. Sewer SC-L-04-F-7 PG 11 F-1 1b Public 662.6 Line Crossing. Install 390,000 55 Low Takoma Branch - Downstream Riffle-Grade Downstream of Ray Road Control Total 21,708.6 $1,590,000

MC= Montgomery County, PG= Prince George's County, DC=District of Columbia

11a= Removal, 1b= Modification Figure 37a - Candidate Fish Blockage Removal Site Photo - Sligo Creek Mainstem Full Name: SSligo Creek Mainstem - S0 ~ 700 ft. Upstream of NW Br. confl uence Project No.: SC-L-04-F-1 ADC Map Book Location: 11 J-3 Approximate Upstream Length 3,000 Opened (ft): General Description: Complete - ~12 in. High Sheet Pile Weir. Install Downstream Riffl e- Grade Control

Figure 37b- Candidate Fish Blockage Removal Site Photo- Takoma Branch

Full Name: Takoma Branch - Chillum Manor Road Culvert Project No.: SC-L-04-F-6 ADC Map Book Location: 6 H-13 Approximate Upstream Length 2,000 Opened (ft): General Description: Complete - ~2 ft High. Concrete Culvert. Install Downstream Riffl e- Grade Control

74 Figure 38 - Lower Sligo Creek Candidate Riparian Restoration Sites

75 Project Ranking 82 Medium 78 Medium Project Score (pts) 500 500 500 83 Medium 5,000 70 Medium Cost ($) Estimated Acquisition General Description Invasives- English Ivy, Invasives- English Ivy, Porcelainberry, Kudzu. Porcelainberry, Kudzu. Enhance Riparian Buffer Enhance Riparian Buffer Enhance Riparian Buffer Invasives- Porcelainberry. Meadow Creation/Restoration (ac) Approx Acreage Total 12.5 $6,500 Ownership 1 1c Private 10 Type Project F-1 11 G-1 1b Public 0.7 Location 11 H-2, J-2 1d Public 0.3 ADC Map Book 37 F-13, G-13; 42 Section) Highway Road to East/West Pepco ROW from Ray M-NCPPC Lower Sligo- WTOP Transmitter Area Raydale Road Trib (Open Project No. Jurisdiction Name SC-L-05-R-4 PG SC-L-05-R-2SC-L-05-R-3 PG PG SC-L-05-R-1 PG Chillum Manor Road Area 6 H-13 1d Public 1.5 MC= Montgomery County, PG= Prince George's DC=District of Columbia 1a=Upland Reforestation, 1b= Riparian 1c= Meadow Creation,1d= Invasive Plant Management, 1e= Stream Valley Land 1 1 Table 24. Lower Sligo Creek: Candidate Riparian Reforestation, Meadow Creation, Street Tree and Invasive Plant Tree Street Meadow Creation, Candidate Riparian Reforestation, Sligo Creek: 24. Lower Table

76 Figure 39 - Candidate Riparian Restoration Photo - Chillum Manor Road Area Full Name: Chillum Manor Road Area Project No.: SC-L-05-R-1 ADC Map Book Location: 6 H-13 Approximate Acreage (ac): 1.5 General Description: Invasives- English Ivy, Porcelainberry, Kudzu. Enhance Riparian Buffer

77 Figure 40 - Lower Sligo Creek Candidate Trash Reduction Sites

78 Project Ranking Project Score (pts) 96 95 High 300 95 High 8,0001,600 82 90 Medium High 3,800 92 High 4,970 79 Medium 3,930 775,230 Medium 793,410 Medium 77 Medium 16,875 77 Medium 35,000 77 Medium Cost ($) Estimated or Equivalent TM includes concrete Marker Stenciling TM Trash Trap Inlets; Outreach Inlets; Outreach Inlets; Outreach Inlets; Outreach Inlets; Outreach Project Signage General Description curb with B-20 SD inlet Stream/No Dumping and InletGuard Custom Designed and Built Volunteer-Based Storm Drain Volunteer-Based Storm Drain Storm Flo Street Sweeping (Weekly), SD Street Sweeping (Weekly), SD Street Sweeping (Weekly), SD Street Sweeping (Weekly), SD Street Sweeping (Weekly), SD Inlet Grates or Inserts @ Select Inlet Grates or Inserts @ Select Inlet Grates or Inserts @ Select Inlet Grates or Inserts @ Select Inlet Grates or Inserts @ Select (mi) Length Approx Total 6.9 $83,211 Ownership 1 Type Project 1a,1c,1d Public 2.0 1a,1c,1d Public1a,1c,1d 1.1 Public1a,1c,1d 2.1 Public 0.7 - - 1 11 G-1 H-13 11 G-2 1c Public NA Location 42 C-1, E-2 1a,1c,1d Public 1.0 11 F-2; G-2, ADC Map Book 11 E-2; E-1; 6 6 F-13; G-13; 11 G-1; H-1; 6 F-13; 6 G-12; G H-13; 11 H-1;11 J 11 E-1; F-1; Riggs Road) Road Device 23rd Avenue) Ray Road (New University Blvd.) (Peabody Street to E/W Highway (New Street to 6th Street) Redtop Road End of Riggs Road (Chillum Hampshire Avenue to Hampshire Avenue to Road to Avalon Place) Eastern Evenue (Laurel New Hampshire Avenue Project ID Jurisdiction Name SC-L-06-T-3 PG SC-L-06-T-2 PG Redtop Road (1 side) 11 G-1 1c Public NA SC-L-06-T-1 DC SC-L-06-T-4 PG Storm Drain Inlet Grates Multiple Locations 1c Public NA SC-L-06-T-5SC-L-06-T-6 PG PG Various Signage Multiple Locations Storm Drain Marker Multiple Locations 1d 1d Public Public NA NA SC-L-06-T-9 PG SC-L-06-T-8 PG SC-L-06-T-7 PG Storm Drain Stenciling Multiple Locations 1d Public NA SC-L-06-T-10 PG SC-L-06-T-11 PG MC= Montgomery County, PG= Prince George's DC=District of Columbia 1a= Street Sweeping, 1b= Manual/Mechanical Removal, 1c= Structural, 1d=Outreach/Education 1 1 Table 25. Lower Sligo Creek: Candidate Trash Reduction Trash Candidate Sligo Creek: 25. Lower Table

79 Figure 41 - Trash Reduction Site Photo - Redtop Road Full Name: Redtop Road Project No.: SC-L-06-T-3 ADC Map Book Location: 11 G-2 Approximate Acreage (ac): NA General Description: Storm FloTM includes concrete curb with B-20 SD inlet

80 Figure 42 - Lower Sligo: Candidate Land Acquisition

81 Project Ranking Project Score (pts) 50,000 63 Low Cost ($) Estimated Acquisition Property Stream Valley Park Land General Description Takoma Branch - Ford Approx Acreage (ac) Ownership 1 Type Project 6 G-13 1e Private 0.5 Location DC Map Book A - Parcel 163 William Ford Property Project No. Jurisdiction Name SC-L-08-L-1 PG MC= Montgomery County, PG= Prince George's DC=District of Columbia 1a= Street Sweeping, 1b= Manual/Mechanical Removal, 1c= Structural, 1d=Outreach/Education Table 26. Lower Sligo Creek: Land Acquisition Land Sligo Creek: 26. Lower Table 1 1

82 Figure 43 - Candidate Land Acquisition Photo

Full Name: William Ford Property - Parcel 163 Project ID: SC-L-08-L-1 ADC Map Book Location: 6 G-13 Approximate Acreage (ac): 0.5 General Description: Takoma Branch - Ford Property Stream Valley Park Land Acquisition

83 VII. Restoration Project Samples

84 Stormwater Retrofi t Type: ‘Wet’ Extended Detention -Retrofi t Existing Facility Application: D.A.>=20 Acres, or Basefl ow Present Water Quality-High; Volume Reduction-Low; Peak Discharge- Expected Benefi ts: High; Wildlife Habitat- Low/Moderate Approx. Unit Costs: $1,000-3,000/acre of drainage Maintenance Fre- Low Expected Longevity High quency Off-line system w/ basefl ow diversion

Type: ‘Wet’ Extended Detention -New Construction Application: D.A.>=20 Acres, or Basefl ow Present Water Quality-High; Volume Reduction-Low; Peak Discharge- Expected Benefi ts: High; Wildlife Habitat- Low/Moderate Approx. Unit Costs: $3,000-5,000/Acre of Drainage Maintenance Fre- Low Expected Longevity High quency Off-line ED wetland

85 Stormwater Retrofi t (Continued) Type: LID-Bioretention (w/Underdrain System) D.A. ~ ≤1.0 acres (Note: multiple systems required for larger Application: D.A.’s) Water Quality- High; Volume Reduction-Moderate/High; Peak Expected Benefi ts: Discharge-Low/Moderate; Wildlife Habitat-low Approx. Unit Costs: $100,000/Impervious Acre Maintenance Fre- Low/Moderate Expected Longevity High quency

Type: LID-Curbside/Street Planter Application: Residential and Arterial Streets Water Quality-Moderate; Volume Reduction-Low/Moderate; Expected Benefi ts: Peak Discharge- Low; Wildlife Habitat-Low Approx. Unit Costs: `$100,000/ Impervious Acre Maintenance Fre- Moderate/High Expected Longevity Moderate quency

86 Stormwater Retrofi t (Continued) Type: LID-”Filterra” Tree Box Filter Application: Residential Streets and Parking Lots Water Quality - Moderate; Volume Reduction-Low; Peak Dis- Expected Benefi ts: charge-Low; Wildlife Habitat Value-Low Approx. Unit Costs: $54,450 - $65,340/Impervious Acre Maintenance Fre- Low/Moderate Expected Longevity Moderate quency

Type: LID Green Roof Application: Residential and Commercial Water Quality - Moderate; Volume Reduction-Low; Peak Dis- Expected Benefi ts: charge-Low/Moderate; Wildlife Habitat Value-Low Approx. Unit Costs: ~$42/square foot Maintenance Fre- Moderate/High Expected Longevity Moderate/High quency

87 Stormwater Retrofi t (Continued) Type: LID-Single Family Home Rain Garden Application: Lot Sizes >= 0.25 Acres Water Quality-High; Volume Reduction- Moderate/High; Peak Expected Benefi ts: Discharge-High; Wildlife Habitat Value-Low Approx. Unit Costs: ~$5,000 per Individual Garden Maintenance Fre- Low/Moderate Expected Longevity High quency

Type: LID-Single Family Home Rain Barrel Application: All Single Family Residential Water Quality-Low; Volume Reduction-Low; Peak Discharge- Expected Benefi ts: Low; Wildlife Habitat Value-None Approx. Unit Costs: $200/Barrel (typically, two per house = $400) Maintenance Fre- Moderate Expected Longevity Moderate quency

88 Stream Restoration Type: Stream Restoration-Channel Morphology (Rosgen-Type) Application: Moderate/Severely Degraded Stream Expected Benefi ts: High Approx. Unit Costs: ~$300/LF Maintenance Fre- Low Expected Longevity High quency

Wetland Creation/Restoration Type: Wetland Creation Application: Riparian Areas w/ Supporting Hydrology Expected Benefi ts: Moderate/High Approx. Unit Costs: Variable Maintenance Fre- Low/Moderate Expected Longevity Moderate/High quency

Small Off-line Wetland

89 Wetland Creation/Restoration (Continued) Type: Vernal Pool Creation Application: Wooded Stream Valley Area w/ Supporting Hydrology Expected Benefi ts: Moderate/High Approx. Unit Costs: Variable Maintenance Fre- Low Expected Longevity High quency

Sligo Creek Vernal Pool Vernal Pool Creation

Fish Blockage Removal/Modifi cation Type: Fish Passage/Riffl e Grade Control Structure Application: Barrier Height <= 5.0 Feet Expected Benefi ts: High Approx. Unit Costs: ~$150,000 per One Foot Barrier Maintenance Fre- Low Expected Longevity High quency

90 Trash Reduction Type: Fresh Creek Trash Netting System Application: Larger Drainage Areas >= 10 Acres Expected Benefi ts: High Approx. Unit Costs: ~$1,000/Acre of Drainage Maintenance Fre- High Expected Longevity Moderate quency

Takoma Branch Trash Trap Installation Fresh Creek Trash Trap

Type: “Storm Flo” End-of-Pipe Trash Catching System Application: Smaller Drainage Areas <= 10 Acres Expected Benefi ts: High Approx. Unit Costs: ~4,000/Acre of Drainage Maintenance Fre- High Expected Longevity High? quency

“Storm Flo”

91 Trash Reduction (Continued) Type: “Regenerative Air” Street Sweeping Application: Public Streets, Alleyways and Parking Lots Expected Benefi ts: Moderate/High for Trash; Moderate for Particulate Pollutants Approx. Unit Costs: ~$50/Curb Mile/Year Maintenance Fre- High Expected Longevity Low/Moderate quency

EPA-Certifi ed Schwartz A4000 Regenerative Air

Type: Storm Drain “InletGuard” Trash Grate Application: Strategically-Targeted Public Streets Expected Benefi ts: High Approx. Unit Costs: ~$500/Inlet Maintenance Fre- Moderate/High Expected Longevity High quency

Storm Drain Inlet Guards Sample

92 VIII. References

1. Center for Watershed Protecti on. April 18 2008. Technical Memorandum: The Runoff Reducti on Method. htt p://www.cwp.org/Resource_Library/Center_Docs/SW/ RRTechMemo.pdf

2. DC offi ce of the Chief Technology Offi cer. 2008. htt p://octo.dc.gov/octo/site/default. asp

3. DC Water and Sewer Authority

4. Fresh Creek Technologies inc. 2008. Design Plans for Takoma Branch Trash Trap

5. Maryland Department of Planning

6. Maryland Department of the Environment. 2008. Chapter 5 Low Impact Development htt p://www.mde.state.md.us/Programs/WaterPrograms/ SedimentandStormwater/stormwater_design/index.asp

7. Maryland Nati onal Capitol Park Planning Commission

8. Montgomery County Department of Environmental Protecti on, Personal correspondence

9. Montgomery Park Planning Department

10. Plan Development Team Membership discussions 2007-2008

11. Price Georges County Department of Environmental Resources, Personal correspondence

12. Prince Georges Planning Department

13. Roscoe Moss Company www.roscoemoss.com

14. Schwarze Industries www.products.schwarze.com

15. United States Department of Interior US Geological Survey 30 Meter Digital Elevati on Model htt p://datagateway.nrcs.usda.gov/Catalog/ProductDescripti on/NED.html

16. Washington Suburban Sanitary Commission

93