CSO 025 / 026 Sewer Separation Project

CSO 025 / 026 Sewer Separation Project


The Combined Sewer Overflow (CSO) 025/026 Sewer Separation project is part of the DC Water Clean Rivers Project’s goal to reduce the volume of combined sewer overflows to the Potomac River to improve water quality and meet Consent Decree requirements. In addition to constructing a tunnel and green infrastructure, DC Water is using sewer separation for two CSO outfalls—CSOs 025 and 026.

The concept of sewer separation means routing sanitary flow to new sewers that will exclusively carry sanitary flow and convey stormwater runoff through the existing piping system that formerly carried combined storm and sanitary flow. The CSO 025/026 sewer system is located within Georgetown, south of the C&O Canal, and collects flow from the blocks bounded by Cecil PL NW, Wisconsin Ave NW, 31st ST NW, and Thomas Jefferson ST NW.

The map below shows the project areas. Construction will occur at three project sites: 
•    Water Street NW Project Site 
•    Wisconsin Avenue NW Project Site 
•    31st Street NW Project Site


Activity Date
Data Collection/Investigation Complete
Design Complete
Construction Begins 4/2021
Construction Complete 9/2022

Community Meeting Presentation

Click here to see the June 7, 2022 presentation about this project.

Click here to see the January 31, 2022 presentation about this project.

Click here to see the August 30, 2021 presentation about this project.

Click here to see the April 20, 2021 presentation about this project.

clean river
Clean Rivers

The Clean Rivers Project is DC Water's ongoing program to reduce combined sewer overflows into the District's waterways - the Anacostia and Potomac Rivers and Rock Creek. The Project is a massive infrastructure and support program designed to capture and clean water during heavy rainfalls before it ever reaches our rivers.

Upcoming Meeting

Board of Directors Meeting

April 24, 2023

Monday 9:00 AM


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Rock Creek Parkway and Virginia Avenue, NW: Temporary Lane Closures

(Washington, DC) –DC Water’s contractor on the Potomac River Tunnel Project will begin performing utility investigations along portions of Rock Cre

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