The Potomac River Tunnel is the next major phase of the DC Clean Rivers Project. The project consists of a large-diameter deep sewer tunnel, diversion facilities, drop shafts and support structures to capture flows from existing combined sewer overflows (CSOs) along the Potomac River and convey them to the Blue Plains Advanced Wastewater Treatment Plan for treatment. The project is needed to reduce CSOs that contribute to water quality impairment of the Potomac River and ultimately the Chesapeake Bay; and to comply with the 2005 Federal Consent Decree entered into by DC Water, the District of Columbia, the US Environmental Protection Agency, and the US Department of Justice, as amended January 2016. CSOs impair water quality by increasing water bacteria levels, contributing to low dissolved oxygen in the water, increasing the potential for fish stress or fish kills and impacts to other aquatic life, and increasing the amount of trash in waterways. An estimated 654 million gallons of CSOs currently enter the Potomac River in a year of average rainfall. The proposed controls are estimated to reduce CSOs to the Potomac River by 93% by volume and reduce their frequency from approximately 74 events to 4 events in a year of average rainfall.

Potomac River Tunnel Corridor Map
Potomac River Tunnel Corridor Map

DC Water and the National Park Service (NPS) are seeking comments on an Environmental Assessment (EA) prepared for the Potomac River Tunnel project. Portions of the project are proposed for construction on lands administered by the NPS. Therefore, the EA has been prepared to document compliance with the National Environmental Policy Act (NEPA), which is required for NPS issuance of construction permits for the project. The EA evaluates impacts based on a range of options for each facility proposed for construction, with a preferred option presented for each structure. The EA can be downloaded from the Project Documents link above. Hard copies of the EA are also available at the following District libraries:

  • Southwest Library, 900 Wesley Place SW
  • West End Library, 2301 L Street NW
  • Georgetown Library, 3260 R Street NW
  • Palisades Library, 4901 V Street NW

How to Comment

The preferred manner for providing comments is via an online form through the NPS Planning, Environment, and Public Comment (PEPC) website, used by the agency to manage official correspondence and to analyze public comments in the planning process. The PEPC project website is located at http://parkplanning.nps.gov/PotomacRiverTunnel.

Comments may also be submitted in writing to: 
DC Clean Rivers Project
ATTN: Potomac River Tunnel EA
Blue Plains Advanced Wastewater Treatment Plant
5000 Overlook Avenue, SW
Washington, DC 20032

Comments must be provided electronically or postmarked by December 4, 2018, to receive consideration. Please be aware that the entire comment submitted – including personal identifying information such as address, phone number, and email address – may be made publicly available. Requests to withhold such personal identifying information from public release will be considered, but there is no guarantee that it will be withheld.

Public Meeting Notice

The ongoing participation of the public is very important to the success of this project. We invite you to attend an open house on Wednesday, November 14, from 6:00 to 8:00 p.m. at West End Library (2301 L St NW, Washington, DC 200037). There, you will be able to discuss the project with NPS and DC Water staff, get your questions answered, and learn more about the project and the EA. For more information or for individuals requiring special assistance at the meeting please contact DC Clean Rivers Project Public Outreach at (202) 787-4717 or by email at dccleanrivers@dcwater.com.