Excavation is underway to access a damaged section of the Potomac Interceptor, a major sewer line that collapsed January 19 along Clara Barton Parkway near the I-495 interchange and the C & O Canal National Historical Park in Montgomery County.
DC Water said the start of excavation marks a key step in the recovery, allowing engineers to inspect the exposed pipe, assess damage, and determine the most effective repair approach while a bypass system continues to divert wastewater downstream.
According to testing released by the Potomac Riverkeeper Network, water samples collected near Lockhouse 10 showed E. coli levels nearly 12,000 times higher than limits considered safe for human contact, with elevated contamination also detected at nearby river access points and downstream in Washington, D.C. The organization estimates that nearly 300 million gallons of raw sewage have entered the Potomac River since the collapse, though upstream samples showed normal conditions, confirming the spill as the source.
DC Water reported that additional pumps have been brought online to support the bypass, which has significantly reduced overflows and, at times, fully contained them for extended periods. Officials said repairs will be complex due to the size of the 72-inch pipe and the volume of wastewater, and a full timeline will not be known until inspections are complete, while coordination continues with federal, state, and local agencies and the public is urged to avoid contact with any remaining wastewater.
Excavation is now underway at the Potomac Interceptor break. Crews are operating eight pumps around the clock, which has greatly reduced overflows. Repair timelines can’t be set until the damaged pipe is fully inspected. Learn more▶️: https://t.co/Pbh55OR8Ug #DCWater pic.twitter.com/PPTb6sdrqW
— DC Water (@dcwater) January 28, 2026
