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The Potomac River is grappling with more than just turbulent waters following a sewage spill near Lockhouse 10, which has dramatically elevated E. coli levels in Washington, D.C. Recent tests indicate contamination levels that exceed safe human contact thresholds by thousands of times.
Lockhouse 10, a historic lock and preserved lockkeeper’s house along the Chesapeake and Ohio (C&O) Canal, was originally constructed to regulate boat traffic during the 19th century. It is now a serene historic site located approximately five miles from downtown Washington, D.C.
The Potomac Riverkeeper Network (PRKN) has disclosed test findings from the polluted waters of the Potomac River. Betsy Nicholas, President of PRKN, noted that the impact appears significantly more severe than previously anticipated.
These tests revealed alarming concentrations of E. coli bacteria. While typically harmless and residing in the intestines of humans and animals, certain strains can produce toxins leading to gastrointestinal issues, as outlined by the Centers for Disease Control and Prevention (CDC).

According to the testing, the sewage spill near Lockhouse 10 has resulted in E. coli levels soaring nearly 12,000 times above the acceptable safety standards, contaminating both the Potomac River and the waters of Washington, D.C.
“These measurements of E. coli bacteria show contamination which is nearly 12,000 times what authorities limit for human contact,” Nicholas said. “So far, almost 300 million gallons have entered the Potomac River, and the long-term impact cannot be overstated. We measured against standards established by Virginia’s Department of Environmental Quality and Maryland’s Department of the Environment.
“We were able to get this information thanks to real-time testing conducted Friday by Dean Naujoks, Potomac Riverkeeper, and Evan Quinter, PRKN volunteer coordinator,” she added.

E. coli is a type of bacteria commonly found in the intestines of people and animals. It is usually harmless but can cause diarrhea and more serious gastrointestinal illness when certain toxin-producing strains contaminate food or water, according to the CDC. (iStock)
Beyond the initial findings, additional testing conducted along the Potomac River shows how far the contamination spread and how dramatically bacteria levels varied depending on location.
Naujoks said the sampling locations were chosen to show contamination at the source of the spill, at popular public recreation areas and miles downstream in Washington, D.C.
“We sampled the sewage discharging from the broken interceptor pipe to the Potomac River near Lock 10 and the result was 4,884,000 MPN – Most Probable Number for E. coli – which is 11,900 times higher than the 410 MPN limit for safe human contact,” he said. “Very nearby, samples collected from the river at the Lock House 10 public river access where people recreate showed values were 7,000 times above the 410 limit.

Testing shows a sewage spill near Lockhouse 10 sent E. coli levels nearly 12,000 times above safe limits, contaminating the Potomac River and Washington, D.C. waters. (iStock)
“We also sampled roughly four miles downstream in D.C. waters at Fletchers Cove, where testing data revealed E. coli levels were 60 times higher than the 410 standard,” he added.
Naujoks said the spill was the result of infrastructure failures that he argues could have been prevented with better maintenance and planning.
“Infrastructure failure is at the root of this disaster – the six-foot-diameter sewage interceptor pipe located this close to the river should have been better maintained to avoid this catastrophe,” Naujoks said. “DC Water needs to come up with a better plan than using a 100-year-old dry canal ditch to capture and contain future sewage releases instead of discharging hundreds of millions of gallons of sewage to the river. One of the largest sewage spills in U.S. history could have been avoided.”
Fox News Digital has reached out to DC Water for comment on the matter.