The Piney Branch Storage Project was first approved as part of DC Water’s Long Term Control Plan federal consent decree in 2005 and revised in 2020.  It will be constructed in the northwest part of Washington, DC, south of the existing CSO 049 and Piney Branch Parkway. The project’s sole purpose will be to divert CSO 049 combined sewage overflows into the East Rock Creek Diversion Sewer (ERCDS) and send it to Blue Plains WWTP for treatment, as required by the revised consent decree. This will reduce the current overflow frequency from 25 per year to one per year and reduce the overflow volume from 39.7 million gallons to 1.4 million gallons – a reduction of 96 percent.  


Environmental Assessment (EA) Date

Data Collection


Impact Assessment

Public Scoping Period January 18-February 16, 2023
EA Released to Public TBD
Public Meeting TBD
Finalize Decision Document TBD
Future Consent Decree Deadlines  
Award Contract for Design May 2024
Award Contract for Construction May 2026
Place in Operation March 2











DC Water and the National Park Service (NPS) are beginning a planning process that includes the preparation of an Environmental Assessment (EA) to comply with the National Environmental Policy Act (NEPA). The EA will analyze potential environmental impacts that would result from implementing the Project. As the coordinating agencies in the preparation of the EA, DC Water and NPS are working closely with multiple stakeholders including residents, Advisory Neighborhood Commissions, District Department of Transportation, District Department of Public Works, District Fire and Emergency Medical Services, District Department of Energy and Environment, District Office of the Deputy Mayor for Planning and Economic Development, District Department of General Services, National Park Service, and the Washington Metropolitan Area Transit Authority. In addition, DC Water is coordinating with multiple federal and local agencies and other organizations through the National Environmental Protection Act and the National Historic Preservation Act compliance procedures.  

Public Participation

Public participation is vital to the NEPA planning process. The NEPA process started with a public scoping meeting on January 18, 2023 and a 30-day public scoping period from January 18 to February 16, 2023, in which the NPS and DC Water gathered public input regarding issues or concerns associated with implementing the proposed project. The webinar from the January 18, 2023 public scoping meeting is posted in the Documents List online at https://parkplanning.nps.gov/dcPineyBranch.

Additional opportunities for public input will be available as the project continues.

Project Location

Piney Branch Storage General Map