E. Coli, Staph Persist in Potomac Weeks After Sewage Spill

Bacteria levels remain elevated near and downstream of the site where hundreds of millions of gallons of raw sewage entered the river.

Feb. 21, 2026 at 4:40am

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Nearly a month after a wastewater pipe broke and spewed hundreds of millions of gallons of raw sewage into the Potomac River just north of Washington, D.C., the latest water testing results from the University of Maryland School of Public Health continue to show high levels of E. coli and S. aureus - commonly called staph, including antibiotic-resistant MRSA. The bacteria are highest near the site of the spill and remain elevated downriver at least through Lock 5, about four miles away.

Why it matters

The sewage spill has exposed residents to raw sewage, which can contain waterborne pathogens including antibiotic-resistant bacteria. This poses serious health risks, including bacterial infections that can cause serious illness and death. The incident also highlights the larger problem of aging and poorly maintained infrastructure, including pipes, pumping stations and treatment facilities, that communities across the country are facing.

The details

Based on water samples collected on February 3, 12, and 17, the E. coli bacteria levels were over 4,000 times above recreational water quality standards on February 3, down from over 10,000 times above EPA standards on January 21, but still 100-200 times above the standard on February 12 and 17. Staphylococcus aureus (staph), including an antibiotic-resistant strain of S. aureus (MRSA), was detected at the site where sewage entered the Potomac on February 3 and 12, and was also detected at sites 6 and 19 miles downriver on February 12.

  • The sewage spill occurred near Clara Barton Parkway in Montgomery County, Maryland, when a pipe taking wastewater from Virginia to the DC Water treatment plant burst on January 19.
  • The University of Maryland's Water Quality, Outreach and Wellness Lab (WOW) has been testing the water and the soil near and downstream of the spill since January 21.

The players

Dr. Rachel Rosenberg Goldstein

Microbiologist and co-principal investigator of UMD's Water Emergency Team (WET).

Dr. Marccus Hendricks

Director of the Stormwater Infrastructure Resilience and Justice (SIRJ) Lab and expert in the effects of aging sewer and stormwater infrastructure.

Potomac Riverkeeper Network (PRKN)

A non-profit organization that collaborates with the University of Maryland to collect water samples.

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What they’re saying

“Though our testing has shown lower levels of E. coli since we began sampling, we continue to see these disease-causing bacteria at levels unsafe for people and animals. To ensure safety, people should continue to avoid coming into contact with the Potomac near the spill site, and with land near the impacted river.”

— Dr. Rachel Rosenberg Goldstein, Microbiologist and co-principal investigator of UMD's Water Emergency Team (WET)

“We don't know for sure that the staph we're detecting downstream is from the sewage. There can be staph and MRSA in the environment from wildlife or other sources. However, the percentage of positive samples that we're finding is higher than what has been previously reported in U.S. surface waters.”

— Dr. Rachel Rosenberg Goldstein, Microbiologist and co-principal investigator of UMD's Water Emergency Team (WET)

“This is not a one-time fix and we must shift our thinking from being reactive and solely focusing on risks in the aftermath of crises, to being proactive. Otherwise, these events will continue to happen at this magnitude, time and time again.”

— Dr. Marccus Hendricks, Director of the Stormwater Infrastructure Resilience and Justice (SIRJ) Lab

What’s next

The UMD team and PRKN are continuing to take water and soil samples, including this week. A long-term plan for comprehensive and ongoing assessments is essential to address the larger issue of aging and poorly maintained infrastructure.

The takeaway

This incident highlights the serious public health risks posed by sewage spills, which can expose residents to waterborne pathogens including antibiotic-resistant bacteria. It also underscores the urgent need for communities to proactively address the problem of aging and poorly maintained infrastructure to prevent such events from happening again in the future.