Rock blockage delays sewer line repair after major Potomac spill

WASHINGTON - More than two weeks after a collapsed sewer line sent massive amounts of wastewater into the Potomac River, crews hit another setback when a large rock blocking repair work was discovered.

What we know:

Engineers say the obstruction, located nearly 30 feet downstream from the original break, will delay full repairs by an estimated four to six weeks. The sewer line collapsed on Jan. 19, releasing roughly 40 million gallons of wastewater a day into the river and raising significant environmental and public‑health concerns.

A bypass system has since been installed, capturing most of the overflow while long‑term cleanup and remediation plans are developed. Additional pumps are still needed to reduce the remaining flow, and engineers will have to stabilize the ground and bring in heavy equipment to break apart the boulder.

READ MORE: Nearly 300 million gallons of sewage has entered Potomac River: PRKN

New CCTV inspection of the Potomac Interceptor showed the rock blockage inside the damaged sewer line is larger than originally expected, extending the repair timeline for cleaning and repairs. (DC Water)

By the numbers:

Water‑quality monitoring continues. The most recent sampling on Feb. 4 showed E. coli levels dropping below 50 at Fletcher’s Boathouse, the Georgetown Waterfront and the Anacostia. Levels at National Harbor, however, rose to 178. The EPA considers levels up to 126 generally safe for recreation; a single sample above 410 is considered unsafe for swimming.

Officials say the drinking‑water supply remains unaffected but continues to urge people to avoid contact with the river, noting that E. coli levels can shift quickly with changing weather.