High Bacteria Levels Found in Potomac River After Major Sewage Spill

University of Maryland researchers detect dangerous bacteria like E. coli and MRSA at site of massive sewage overflow.

Published on Feb. 6, 2026

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University of Maryland researchers have discovered extremely high levels of disease-causing bacteria, including E. coli over 10,000 times above safe limits and antibiotic-resistant MRSA, in the Potomac River following a massive sewage spill last month. The contamination stems from a pipe rupture that released hundreds of millions of gallons of raw sewage into the river, one of the largest such incidents in U.S. history.

Why it matters

The findings raise urgent public health concerns about the risks posed by aging water infrastructure, as sewage overflows are a common problem across the country. Exposure to the contaminated water and land can lead to serious infections, highlighting the need for infrastructure investment and maintenance to prevent similar incidents.

The details

Water samples collected by the UMD research team revealed E. coli levels more than 10,000 times above EPA recreational water quality standards at the spill site. Staphylococcus aureus and the antibiotic-resistant MRSA strain were also detected at multiple locations along the river. The researchers advised residents near the spill site in Maryland, Washington D.C., and downstream areas to avoid contact with the affected water and land until bacteria levels return to safe standards.

  • On January 19, a pipe rupture released hundreds of millions of gallons of raw sewage into the Potomac River.
  • On January 21, initial samples showed E. coli concentrations exceeding safe limits by over 10,000 times.
  • One week later, on January 28, E. coli levels at the same location remained over 2,500 times above safe limits.

The players

Dr. Rachel Rosenberg Goldstein

A microbiologist and assistant professor at the University of Maryland's Department of Global, Environmental, and Occupational Health, who led the testing through her Water Quality, Outreach and Wellness Lab.

Dr. Marccus D. Hendricks

An associate professor of Urban Studies and (Environmental) Planning at the University of Maryland, who co-leads the Water Emergency Team with Dr. Goldstein.

Potomac Riverkeeper Network

A community organization that worked with the UMD research team to collect samples.

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What they’re saying

“People coming into contact with the impacted water or land are at risk of becoming infected with these bacteria, which can lead to serious health conditions.”

— Dr. Rachel Rosenberg Goldstein, Microbiologist and Assistant Professor (UMD Press Release)

“Investment, maintenance and rehabilitation of drainage and other water resources infrastructure have been slow and the effects of this are clear in this Potomac sewage spill.”

— Dr. Marccus D. Hendricks, Associate Professor of Urban Studies and (Environmental) Planning (The Washington Times)

What’s next

The Water Emergency Team continues to collect water and soil samples in the affected area, working directly with community organizations to share findings with residents and local policymakers.

The takeaway

This incident highlights the urgent need for significant and ongoing investment in upgrading and maintaining the nation's aging water infrastructure, as sewage overflows are a persistent problem that puts public health at risk. Solving this issue will require a long-term, comprehensive approach to infrastructure improvements.