Sewage Spill Sends Potomac River E. coli Levels Nearly 12,000 Times Above Safe Limit Near D.C.

Testing by the Potomac Riverkeeper Network shows a massive sewage spill near Lockhouse 10 along the C&O Canal has sent E. coli levels in the Potomac River soaring to nearly 12,000 times above the recreational safety standard just five miles upstream from downtown Washington, D.C. In samples taken Friday, pollution at the broken sewage interceptor pipe measured 4,884,000 MPN—about 11,900 times higher than the 410 MPN limit set by Virginia and Maryland environmental regulators—with water at a nearby public access point still 7,000 times over the limit and levels at Fletchers Cove in D.C. about 60 times too high. Potomac Riverkeeper Dean Naujoks and PRKN President Betsy Nicholas say nearly 300 million gallons of sewage have already flowed into the river and warn that the infrastructure failure and long‑term impacts "cannot be overstated." The group is urging the public to stay out of the water in affected areas while officials assess the damage and debate how a major interceptor pipe was allowed to fail so catastrophically in one of the nation’s most visible watersheds. The incident underscores aging wastewater infrastructure risks in the capital region and raises fresh questions about how quickly local and federal agencies will move to repair, upgrade and monitor sewer lines that run along heavily used rivers.