DC Water will continue daily Potomac River water quality testing through July 31. The testing is part of ongoing monitoring after the January 19 collapse of a section of the Potomac Interceptor, a major sewer line. Testing had been expected to move to weekly after the July 4 holiday period.

Customers, residents, and river users will continue to receive daily testing results while the Maryland Department of the Environment (MDE) and DC Water finalize an updated rehabilitation plan. Results over the past few months show the Potomac River is back within its normal range, with typical changes caused by rain, stormwater runoff, and other known factors.

DC Water is working with MDE to submit an updated cleanup plan by July 15. Any changes in frequency with water quality testing after July 31 will be coordinated with MDE.

Water quality results will continue to be posted on DC Water’s website and the District Department of Energy and Environment’s Potomac Interceptor Monitoring Dashboard. Sampling will pause July 3–5 at District locations and National Harbor because of Potomac River closures and added security for America 250 events and fireworks.

At the collapse site, the C&O Canal cleanup is nearly complete. DC Water is performing soil testing in coordination with National Park Service and addressing any remaining areas of concern. DC Water expects to finish the cleanup in the canal by mid-July, then begin work to repair the canal lining and restore the canal and lock structures.

DC Water is also repairing the Potomac Interceptor at the collapse site near Rock Run in Cabin John, Maryland, and at four other priority locations. These locations were selected after DC Water performed new inspections on the 54 miles of the pipe using advanced tools.

Work began last month to set up temporary bypass pumps and pipes to move wastewater around work areas while repairs are made. This keeps wastewater moving safely and helps avoid sewer service interruptions.

Rock Run / Cabin John, Maryland

• Construction of temporary bypass system is underway with about 2000 linear feet of the pipeline complete.
• Crews will repair 72-inch and 66-inch sections of the sewer pipe.

Pennyfield Lock, Potomac, Maryland

• Construction of temporary bypass system and pipeline is 75% complete.
• Crews are doing daily site inspections along the pipe.
• Monitoring equipment is installed to alert teams to possible leaks or pipe problems.
• Next week crews expect to begin applying geopolymer – a strong cement-like liner inside the most critical pipe section.

Dulles International Airport, Loudoun County, Virginia

• Construction of temporary bypass system and pipeline is complete.
• Crews expect to begin lining the pipe with geopolymer in mid-July.
• No airport service impacts are expected.

Broad Run, Loudoun County, Virginia

• Construction of the temporary bypass pipeline is about 95% complete, and pumps are on site.
• Crews are raising supports because water levels can rise during major storms.

DC-Maryland Border Along Clara Barton Parkway

• Site preparation is underway.
• Brush and tree removal is about 75% complete.
• Construction of the temporary bypass pumping system and pipeline is expected to begin in mid-July.

DC Water is doing extensive outreach in the community to share updates with nearby residents, businesses, community leaders, local officials, and partner agencies as the work continues.

The Potomac Interceptor is one of the region’s largest sewer lines. It carries about 60 million gallons of wastewater each day from parts of Northern Virginia, Maryland, and the District to DC Water’s Blue Plains Advanced Wastewater Treatment Plant.

For more information about the Potomac Interceptor Rehabilitation and each project location, visit dcwater.com/potomacinterceptor.