Major sewage spill forces Potomac River closure across three states

A major sewage spill in the Potomac River has triggered emergency declarations and health warnings across Virginia, Maryland, and the District of Columbia after a critical sewer line collapsed in Montgomery County, Maryland on January 19, 2026.

The failure of the Potomac Interceptor, a 72-inch diameter pipe that normally carries up to 60 million gallons of wastewater daily from Virginia and Maryland to a treatment plant in DC, released more than 200 million gallons of untreated sewage into the river. The collapse occurred near Clara Barton Parkway, and despite a bypass system installed by DC Water on January 24, additional overflows were reported in early February.

Background

The Potomac Interceptor is a critical piece of infrastructure for the region's wastewater system. It carries sewage from across Virginia and Maryland to the Blue Plains Advanced Wastewater Treatment Plant in Washington, DC, where it would normally be processed before any discharge. When the pipe failed, untreated sewage containing bacteria, viruses, and harmful chemicals flowed directly into the river.

Authorities moved quickly to contain the damage. DC Water completed a bypass system within five days of the collapse, rerouting wastewater around the damaged section and back into the functioning sewer system. However, the initial spill had already contaminated a significant stretch of the river.

"DC Water has not reported any sewage overflow since February 9," according to the DC Department of Energy and Environment, indicating that containment efforts have been effective in preventing new discharges.

The timeline of the incident shows the severity of the situation. The initial collapse on January 19 was followed by the bypass installation on January 24. Then, in early February, additional overflows occurred before being stopped by February 9. Repairs to the actual pipe are expected to take four to six weeks from the time of the initial failure.

Key Details

Health and Safety Warnings

Authorities have issued clear guidance about the risks. Untreated sewage contains E. coli bacteria that, at certain levels, poses serious health risks to humans. It also carries other dangerous bacteria, viruses, and chemicals that can cause illness.

Despite the sewage spill, drinking water remains safe across the region. DC Water's drinking water system is completely separate from the wastewater system. The intakes for drinking water are located upstream of where the sewage entered the river, and authorities have taken additional precautions by closing intakes at Little Falls downstream as well.

Virginia issued a recreational advisory on February 13 that extends for 72.5 miles of the river, from the American Legion Memorial Bridge near Washington, DC to the Harry W. Nice Memorial Bridge in King George County. The advisory warns against swimming, wading, tubing, and kayaking where people might be fully submerged. Maryland has issued similar warnings for its portion of the river.

Shellfish and Environmental Impacts

Maryland has closed shellfish harvesting areas from the spill location to the Harry W. Nice Bridge, affecting the Potomac River in Charles County and bordering Virginia areas. Virginia's shellfish growing areas, which begin downstream of that bridge, have not been affected and remain open.

Environmental officials are monitoring the river for broader impacts. In the days immediately after the spill, some fish kills were reported, though they were not verified at the time due to icy conditions. Authorities estimate that water takes approximately three weeks to flow through the District's portion of the river, from Chain Bridge to the I-495 Wilson Bridge. As temperatures warm and ice melts, bacteria levels may fluctuate as more sewage trapped in ice is released into the water.

Monitoring and Response

DC Water began daily bacteria monitoring at six locations starting January 29. The DC Department of Energy and Environment increased E. coli monitoring from monthly to weekly and is exploring partnerships to add more testing locations. Early data showed significant bacteria reductions in the two weeks after the bypass was installed.

Authorities are planning fish and wildlife surveys beginning in late February and continuing into spring to assess whether the spill has caused larger environmental damage. Multiple agencies are involved in the response, including the Environmental Protection Agency, the National Park Service, and state environmental departments.

DC Water has hired an environmental company to plan restoration efforts for the spill site, the C&O Canal, and other damaged areas. These restoration plans must meet regulatory requirements set by federal and state authorities.

What This Means

The spill represents one of the largest sewage releases into the Potomac River in recent history. The river's ability to recover depends partly on natural processes—water flow, temperature changes, and microbial action—but also on how quickly repairs are completed and how effectively authorities monitor conditions.

Residents and visitors in the affected areas face restrictions on river activities that could last several more weeks. People who cannot avoid contact with the river are advised to wash thoroughly with soap and water afterward. Those with weakened immune systems, parents of newborns, and other vulnerable populations face heightened risks and are urged to exercise special caution.

The incident has drawn attention to the aging infrastructure that serves the region's wastewater system. The Potomac Interceptor is a critical component of that system, and its failure highlights the importance of maintaining and upgrading aging pipes that serve millions of people across three jurisdictions.