Advocates and university researchers call spill one of the largest in decades, urge expanded testing and criticize DC Water communications

Advocates and academic researchers at the committee briefing said independent sampling shows the Potomac interceptor rupture released an exceptionally large volume of sewage and introduced a substantial nutrient and pathogen load to the river, and they urged expanded and sustained monitoring and clearer public communications.

Betsy Nicholas, president of the Potomac Riverkeeper Network, said the group's estimate is "roughly 250 to 275,000,000 gallons" released and that the spill added what the group approximated as 75,000 pounds of nitrogen, a nutrient load she compared to a large wastewater plant. Nicholas urged officials and media to use the term "partial containment" rather than language implying the river was fully free of discharge, saying some public messaging created confusion about ongoing releases.

Field and lab findings: "Dean" (Potomac Riverkeeper staff) described on‑site sampling and satellite imagery that showed a visible plume and reported independent E. coli and pathogen results that, at some sites, exceeded EPA recreational benchmarks by orders of magnitude. He said independent sampling on Feb. 3 found levels "4,000 times higher than EPA standard for safe recreational use" at impacted sites and flagged continued releases after initial containment claims.

University analysis: Rachel Rosenberg Goldstein, assistant professor at the University of Maryland's School of Public Health, described lab testing focused on indicator and pathogen bacteria. Her lab identified staphylococcus aureus at the spill site and documented MRSA at Lock 10; she told the committee her team found staph aureus at Lock 10 on Jan. 28 and again on Feb. 3 and detected MRSA at the site. She urged expanded pathogen testing (beyond E. coli), sediment sampling and longer‑term monitoring through the spring and summer to understand lingering risks.

Regulatory and economic concerns: MDE said drinking‑water intakes are upstream and were not affected, but that it issued a precautionary shellfish closure near the 301 Bridge in Charles County and will review restoration plans and sampling before reopening. Advocates said market and perception impacts could be significant for riverfront businesses, shellfish harvesters and recreational users and asked for coordinated messaging tied to data to avoid unnecessary economic harm while protecting public health.

Transparency and next steps: Advocates asked DC Water to provide internal SCADA monitoring data showing flows, pump operations and timing of releases; they asked regulators to fund or coordinate additional third‑party sampling. University researchers said they stand ready to collaborate on expanded pathogen testing and ongoing weekly sampling at multiple downstream sites.

The committee recorded advocacy requests for continued weekly (and where appropriate daily) sampling, sediment monitoring, expanded pathogen panels (including genetic methods for difficult‑to‑culture bacteria) and a central public information resource with real‑time overflow and sampling updates.