"A wastewater spill into the Potomac River that began last month now appears to be one of the largest in American history.

DC Water, a local water utility, said in a press release last week that part of a sewer system known as the Potomac Interceptor collapsed along the Clara Barton Parkway on Jan. 19. In that same release, the utility said it “estimates that approximately 243 million gallons of wastewater has overflowed from the collapse site.”

On Monday, DC Water said there had been a “significant overflow” Sunday amid a “high flow period,” with some bypass pumps not in service at the time.

Potomac Riverkeeper Network, a local environmental advocacy group, claimed in a Facebook post Wednesday that the sewage spilled had topped 300 million gallons."

Tara Suter reports for The Hill February 12, 2026. [2]