EPA assumes water sampling role following Potomac Interceptor collapse

The U.S. Environmental Protection Agency will take over daily water quality sampling as part of the federal response to the Potomac Interceptor collapse, replacing monitoring efforts previously conducted by the District of Columbia Department of Energy and Environment.

EPA said it will continue sampling at the same locations and process results at its Environmental Science Center in Fort Meade, with data expected to be publicly available approximately three days after collection.

“Since President Trump immediately granted DC’s request for federal assistance responding to the sewage crisis at the Potomac Interceptor site, EPA has led a successful, coordinated federal effort,” said EPA Senior Response Officer and Assistant Administrator for Water Jess Kramer in an EPA press release. “EPA taking over the daily water sampling is the next step in that coordinated federal response. We will provide accurate, timely results to the public and continue working to ensure that repairs and remediation occur as quickly as possible.”

The Potomac Interceptor, a major sanitary sewer conveying up to 60 million gallons per day to Blue Plains Advanced Wastewater Treatment Plant, experienced a collapse in January 2026, releasing hundreds of millions of gallons of untreated sewage into the Potomac River.

In response, DC Water implemented a controlled bypass system using the C&O Canal to contain the spill and redirect flows back into the interceptor system for treatment.

EPA and federal partners continue to support response efforts on-site, including stormwater diversion, remediation and technical assistance. Officials said drinking water supplies remain unaffected, as the contamination occurred downstream of the Washington Aqueduct’s primary intake.