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.
Based on water samples collected on February 3, 12, and 17, the bacteria are highest near the site of the spill, at Lock 10 . They remained elevated downriver at least through Lock 5 near Little Falls, about four miles away, at most sampling dates. The ground near the spill – visibly dotted with the detritus of the sewage water – has also tested positive for staph.
“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,” said Dr. Rachel Rosenberg Goldstein, microbiologist and co-principal investigator of UMD’s Water Emergency Team (WET). “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.”
Key results include:
“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,” Goldstein said.
“It is encouraging to see E. coli levels generally decreasing over time since the original sewage spill, especially as we move farther downstream, yet the consistent presence of MRSA at the spill site and staph downriver emphasizes continued possible health risks that need to be monitored.”
The 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. Goldstein’s Water Quality, Outreach and Wellness Lab (WOW) has been testing the water and the soil near and downstream of the spill since Jan. 21, collaborating with the Potomac Riverkeeper Network (PRKN) to collect samples.
As part of the University of Maryland’s Water Emergency Team, Goldstein and Co-Principal Investigator Dr. Marccus Hendricks, director of the Stormwater Infrastructure Resilience and Justice (SIRJ) Lab and expert in the effects of aging sewer and stormwater infrastructure, lead a community-driven, rapid response research team for sanitary sewer overflows, household backups and environmental contamination. Goldstein is based in the UMD School of Public Health. Hendricks is based in the UMD School of Architecture, Planning and Preservation.
The sewage spill into the Potomac, says Hendricks, is indicative of a larger and more pervasive problem facing communities across the country: aging and poorly maintained infrastructure, including pipes, pumping stations and treatment facilities.
With containment and public health messaging established and repairs underway, a long-term plan for comprehensive and ongoing assessments is essential, he said, suggesting an “all hands on deck” approach that involves local, federal and third-party partners.
“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,” he said. “Otherwise, these events will continue to happen at this magnitude, time and time again.”
Wastewater overflows expose residents to raw sewage, which can contain waterborne pathogens including antibiotic-resistant bacteria. The effects can be serious, including bacterial infections that can cause serious illness and death, according to WET.
To reduce health hazards, the team recommends not walking pets in the affected areas, avoiding boating or other activities at and directly downstream of the spill, and avoiding fishing in the immediate vicinity.
The UMD team and PRKN are continuing to take water and soil samples, including this week.
The WET project regularly works directly with community organizations and neighborhood associations, with a commitment to sharing lab research findings with affected communities and local policymakers.
Led by the UMD School of Public Health and School of Architecture, Planning, & Preservation, WET is one of 16 UMD Grand Challenges Team Grants that provide three years of funding to research teams seeking solutions to the grand challenges of our time.
Previous results can be found in the Feb. 5,2026, UMD news release .
To request an interview with Dr. Goldstein, please contact sph-comm@umd.edu . To request an interview with Dr. Hendricks, please contact mapp-communicate@umd.edu .