Approved: Water Tunnel Under Waterfront Park

An environmental assessment for the Potomac River Tunnel construction project, which will lead to major excavation work in a swath of Georgetown Waterfront Park, has been completed by the National Park Service. The proposal by DC Water to move forward with the plan, intended to improve water quality and reduce combined sewer overflows into the Potomac, was also approved.  

The announcement by the Park Service came on April 13.

The tunnel project will be begin advanced utility relocations in summer 2021, according to DC Water. Tunnel construction will not begin until summer 2023.

DC Water has also scheduled other work — a sewer separation project in Georgetown for later this year.

“We will be meeting with DC Water next week to better understand the timeline for the more imminent project,” Advisory Neighborhood Commissioner Lisa Palmer told The Georgetowner. “The contractor’s notice to proceed will likely be in December, but that is not confirmed at this time.”

Sited primarily on Park Service land in Georgetown, the proposed Potomac River Tunnel project has been under discussion and review for over two years. The tunnel is part of DC Water’s Clean Rivers Project. When completed in 2030, it is expected to reduce the volume of combined sewer overflows into District waters by an estimated 96 percent. Another anticipated result is a decrease in the annual frequency of overflow events in years of average rainfall from approximately 74 to four.

The project involves construction of diversion facilities and other supporting infrastructure to intercept overflows (which occur when capacity is exceeded during storms) from the existing combined sewer system and divert them to the tunnel. Once diverted to the tunnel, excess flows will be carried by gravity to DC Water’s Blue Plains Advanced Wastewater Treatment Plant.

“We have seen the Anacostia River Tunnel, with its tremendous performance, bring a resurgence to that river and its banks,” said DC Water CEO and GM David L. Gadis. “We know that the projects we have planned for the Potomac will dramatically improve the health of the river and the quality of life for those who enjoy it. Cleaner rivers invite more recreation and entertainment, as well as economic vitality.”

Agreements about the project negotiated between various National Historic Preservation Act agencies, the Park Service, DC Water, the DC Historic Preservation Office and the National Capital Planning Commission are available at



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