The Potomac River, a vital waterway flowing through Washington, D.C., Maryland, Virginia, and West Virginia, experienced a catastrophic sewage spill beginning on January 19, 2026, when a 60-year-old section of the Potomac Interceptor sewer line collapsed near the Clara Barton Parkway in Montgomery County, Maryland.

This 72-inch pipe, which transports up to 60 million gallons of wastewater daily from Virginia and Maryland to the Blue Plains Advanced Wastewater Treatment Plant in southwest D.C., failed during ongoing rehabilitation work that had begun in September 2025, likely due to aging infrastructure and structural weaknesses.

The collapse caused an immediate overflow, allowing raw sewage to gush directly into the river unencumbered for nearly a week, resulting in over 240 million gallons—possibly up to 300 million—of untreated waste contaminating the water, marking one of the largest such spills in U.S. history and spiking E-coli levels to dangerous heights.

Efforts to mitigate the disaster involved installing pumps on January 23 to divert the flow around the rupture and route it to the treatment facility, though intermittent spills continued into February, with full repairs expected to take four to six weeks amid an ecological crisis of historic proportions and political finger-pointing from figures like President Trump blaming local Democratic officials for infrastructure neglect.