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Title: Anacostia Watershed Restoration, Prince George's County, Maryland : Ecosystem Restoration Feasibility Study and Integrated Environmental Assessment, Final Report and Appendices
Authors: United States. Army. Corps of Engineers. Baltimore District
Keywords: Anacostia River Watershed (Md. and Washington; D.C.)
Restoration ecology
Environmental management
Environmental protection
Publisher: United States. Army. Corps of Engineers. Baltimore District.
Abstract: This feasibility study report and integrated environmental assessment presents alternatives for restoring degraded aquatic ecosystem structure and function in the Anacostia River watershed in Prince George’s County, Maryland. This study is being conducted under the authority of a 1988 resolution of the House Committee on Public Works and Transportation to evaluate watershed improvements. In 2014, United States Army Corps of Engineers (USACE) entered into a Feasibility Cost Sharing Agreement (FSCA) with Prince George’s County to conduct this study. This study has been evaluated pursuant to the National Environmental Policy Act (NEPA) of 1969, as amended, and an environmental assessment (EA) is integrated within this report. The proposed solution for stream restoration will have no significant adverse impacts on the quality of the natural and human environment. The recommended plan provides substantial aquatic ecosystem restoration within the stream reaches and contributes to a comprehensive watershed restoration strategy. The Anacostia River watershed encompasses approximately 176 square miles, located entirely within the Washington, D.C. metropolitan area. The drainage area within Prince George’s County is approximately 86 square miles, accounting for almost one half of the total Anacostia River watershed. The Anacostia River flows through Maryland and then the District of Columbia into the Potomac River and Chesapeake Bay. The Anacostia River watershed in Prince George’s County is highly urbanized with large areas of impervious surface cover. Human alteration of the natural landscape in the Anacostia River watershed has severely degraded stream ecosystems. Biological communities in the Anacostia River are degraded due to sediment and in-stream habitat related stressors, such as channel alteration (including channelization by USACE for flood risk management), channel erosion and instability, scouring and transport of suspended sediments, fish blockages, and alterations of riparian buffer zones. Resident fish species and abundance are significantly decreased from historical levels. Anadromous fish species of concern, primarily alewife and blueback herring, which once inhabited the study stream reaches in abundance are no longer able to access their historical spawning grounds. Currently, river herring access only about 20 percent of their historical range on Northwest Branch and 10 percent on Northeast Branch. Approximately 23 miles of stream (18 stream segments) were evaluated for restoration potential throughout the Anacostia River watershed in Prince George’s County. Based on site selection criteria, approximately 11 miles of stream (10 stream segments) were selected for further study. These segments are located in six Anacostia River subwatersheds, including Sligo Creek, Northwest Branch, Paint Branch, Indian Creek, Little Paint Branch, and Northeast Branch. Primary project objectives include restoring in-stream physical habitat in the selected stream reaches and enhancing aquatic ecosystem resilience by restoring fish passage and longitudinal connectivity. Twenty-four potential management measures were identified to meet project objectives and were combined into six alternatives that were screened based on planning constraints and considerations, ecosystem restoration benefits, impacts, cost, implementability, and sustainability. The alternatives that best met project objectives were carried forward, including natural channel design. The no action alternative was also carried forward as a basis for comparison. For the natural channel design alternative, concept-level design alternatives and associated parametric costs were prepared for each stream reach. Ecosystem restoration benefits for these were calculated, including for two in-stream habitat metrics, which were based on the Maryland Biological Stream Survey’s (MBSS) Physical Habitat Index (PHI). The PHI is a model used to quantify the quality of important in-stream habitat metrics. This use of this model was coordinated with the USACE National Ecosystem Restoration Planning Center of Expertise and approved by USACE Headquarters. The ecosystem restoration benefits and costs for the no action and design alternatives for fifteen stream segment combinations, were included into cost effectiveness/incremental cost analyses to identify the most cost effective alternative plans for stream restoration. In accordance with the Economic and Environmental Principles and Guidelines for Water and Related Land Resources Implementation Studies plans were evaluated for cost effectiveness; contributions to planning objectives; significance of outputs; and acceptability, completeness, efficiency, and effectiveness were used to recommend the plan. Plans were initially screened based on cost effectiveness. The recommended plan, Plan NW-C + NE-A, was selected from the final array of plans because it most completely meets the planning objectives to restore aquatic habitat and increase connectivity. Plan NW-C + NE-A consists of the restoration of in-stream habitat in six stream reaches, including three in the Northwest Branch subwatershed and three in the Northeast Branch subwatershed. The recommended plan restores 7 miles of in-stream habitat, 4 miles of fish passage, and connects 14 miles of previously restored habitat. The plan removes fish blockages on Northwest Branch and Sligo Creek providing anadromous fish species of concern access to their historical range on Northwest Branch and facilitating the migration of fish to higher quality habitat upstream of Northeast Branch. For resident fish and benthic macroinvertebrates, habitat improvements resulting from the plan will include increasing diversity of depth and velocity conditions and stabilizing substrate to support species diversity and abundance. With removal of fish blockages and substantial improvements in in-stream aquatic habitat, river herring access to historical spawning grounds will increase from approximately 20 percent to 83 percent on Northwest Branch and from 10 percent to 90 percent on Northeast Branch; thereby, contributing to increases in the populations of these fish. As a component of comprehensive watershed restoration, which includes water-quality improvements being conducted by other agencies, habitat improvements are expected to lead to increased indices of biotic integrity for fish and benthic organisms. The recommended plan will not have an adverse impact on any threatened or endangered species or their critical habitat. Project construction will result in localized, short-term, and minor detrimental environmental impacts to water quality, air quality, and noise levels; in-stream work will cause unavoidable destruction of some common aquatic organisms. All adverse effects will be minimized through utilization of best management practices and activities will be conducted according to state and federal requirements. Project impacts are temporary in nature and habitat will be replaced in kind or better; therefore, no compensatory mitigation is required. The majority of the project work will be confined to the area in between the stream banks, and based on cultural resource surveys is not expected to result in adverse impacts to cultural resources. Access roads and staging areas will not include subsurface excavation and will be confined to previously disturbed areas when possible. In addition to restoring habitat, the proposed restoration enhances federal investments by connecting to previous USACE stream restoration, including on Paint Branch (Continuing Authorities Program Section 206) and Northwest Branch (Continuing Authorities Program Section 1135). Furthermore, the recommended plan restores aquatic ecosystems that were directly degraded by a USACE flood risk management project implemented on Northwest Branch, Northeast Branch, Paint Branch, and Indian Creek in the 1970s. Restoration of the Anacostia River watershed, as a contributing subwatershed to the Chesapeake Bay, supports Executive Order 13508 for restoration of the Chesapeake Bay, the Chesapeake Bay Program outcomes, and the Anacostia Restoration Plan goals. The Urban Waters Federal Partnership is also supported by reconnecting urban areas with their waterways. Project first cost of the recommended plan is $34,106,000. Operation, maintenance, repair, rehabilitation, and replacement (OMRR&R) expenses are expected to be minimal and are estimated at $22,000 per year. The federal portion of the estimated first cost is $22,169,000. The non-federal sponsors’ portion of the required 35 percent cost share of total project first costs is $11,937,000, which includes 100 percent of the real estate costs (land, easements, rights-of-way, and relocations).
Description: Feasibility Study and Integrated Environmental Assessment
Rights: Approved for Public Release; Distribution is Unlimited
Appears in Collections:Environmental Documents

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