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

EA Released to Public TBD
Public Meeting TBD
Finalize Decision Document TBD
Future Consent Decree Deadlines Date
Award Contract for Design May 2024
Award Contract for Construction May 2026
Place in Operation March 2030


As the coordinating agencies in the preparation of the EA, DC Water and the National Park Service 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.  

Project Location

Piney Branch Storage General Map