EPA to Take Over Potomac River Water Quality Sampling Near Interceptor Site

EPA to Take Over Potomac River Water Quality Sampling Near Interceptor Site

March 16, 2026

WASHINGTON - Today, as part of the ongoing federal responseto the Potomac Interceptor collapse, U.S. Environmental Protection Agency (EPA) will assume responsibility for water quality sampling previously conducted by the DC Department of Energy and Environment (DOEE). EPA will utilize the same locations as the previous DOEE sampling, which can be seen on the map below.

"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. "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."

EPA will conduct sampling daily, which will continue to be processed at EPA's Environmental Science Center located at Fort Meade, MD. The results for each day's sampling will be evaluated and quality assured before being posted publicly on DOEE's Potomac Interceptor MonitoringExit EPA's website webpage. Postings for each sample result will be available approximately three days after each sampling event occurs.

In addition to water quality sampling, EPA and its federal partners have and continue to assist on the ground, providing stormwater diversion and management infrastructure, site remediation work, and general technical assistance.

Background

The Potomac Interceptor is a sanitary sewer line in Maryland that conveys up to 60 million gallons of wastewater every day from parts of Virginia and Maryland to DC Water's Blue Plains Advanced Wastewater Treatment Plant. A collapse occurred late Monday, January 19, 2026, in a 72-inch diameter section of the pipe causing hundreds of millions of gallons of untreated sewage to escape and impact the nearby Potomac River. The Potomac Interceptor is managed by DC Water.

Early in the morning of January 25, 2026, DC Water activated a controlled bypass system that utilizes a portion of the C&O Canal to protect the Potomac River from further contamination by containing the spill and redirecting it back into an undamaged portion of the Potomac Interceptor where it is transported for treatment.

According to the operators of the Washington Aqueduct, which collects source water to be treated and distributed as safe drinking water, there has been no impact to drinking water. Any sewage overflow that occurred has been downstream of the Aqueduct's primary intake facility.