02/25/2026
NEWS RELEASE: Maryland Department of the Environment Releases Latest Sampling Results Maintaining Positive Shellfish Conditions After Potomac Interceptor Spill
Precautionary Harvesting Closure to be Lifted March 10; Water Quality Monitoring Ongoing
BALTIMORE (February 25, 2026) — The Maryland Department of the Environment (MDE) today announced the results of recent water quality monitoring by the State that continue to show no evidence that shellfish harvesting waters of the Potomac River are affected by the Potomac Interceptor sewage spill further upstream. Pending further confirmation testing, a precautionary closure will be lifted on March 10.
“The standards for approving areas for shellfish harvesting are rigorous,” said Maryland Department of the Environment Secretary Serena McIlwain. “We continue to work in partnership with our fellow State agencies and our riverkeepers to ensure everyone can be confident in enjoying seafood from downriver areas of the Potomac River and throughout the Chesapeake Bay.”
MDE’s Water and Science Administration is responsible for regulating shellfish harvesting waters. The effort has three parts: 1) identifying and eliminating pollution sources, 2) collecting monthly water samples for bacteriological examination; and 3) examining shellstock samples for bacteriological contamination and chemical toxicants.
Following the spill, the department closed a small portion of the Potomac River approximately 60 miles from the site as a precaution. The closure spans from the Port To***co River region down to the U.S. Route 301 bridge, covering Charles County and bordering Virginia areas. Two rounds of sampling, conducted as soon as the frozen river thawed, showed f***l coliform levels well below the national standard for approved shellfish harvesting; the results are consistent with 40 years of routine seasonal data for this location.
“Maryland participates in the National Shellfish Sanitation Program to ensure the state’s oyster-growing waters meet rigorous health and safety standards,” said Maryland Department of Natural Resources Secretary Josh Kurtz. “We work closely with the State’s departments of health and the environment to protect oyster and fish populations for the benefit of everyone who enjoys eating them. We’re thankful that environmental testing conducted by our sister agencies shows that Maryland oysters continue to meet these high safety standards.”
The closed portion of the river does not impact shellfish harvest in other areas—including other areas of the Potomac that are approved or conditionally approved for shellfish harvest. The precautionary closure also does not apply to fish or crabs. D.C. Water, the operator of the sewage line, has reported no spills into the river since Feb. 9.
Based on monitoring results available to date, conditions within the Potomac River Fisheries Commission jurisdictional waters continue to trend positively. Current information indicates conditions remain favorable, and the commission will continue coordinating closely with Maryland and Virginia partner agencies, monitoring incoming data, and providing updates as additional information becomes available.
“The stretch of the Potomac River within the Potomac River Fisheries Commission’s jurisdiction remains open for fishing and will open for crabbing when the season begins, with conditions continuing to improve,” said Potomac River Fisheries Commission Executive Secretary Ronald Owens.
“Buying Maryland seafood means buying safe seafood, and the proactive testing and monitoring by our partner agencies continues to ensure that consumers can be confident in the product they are bringing home to their families from Maryland’s waters,” said Maryland Department of Agriculture Secretary Kevin Atticks. “We stand beside the departments of environment and natural Resources to remind consumers to Eat Like a Marylander with confidence.”
Oysters currently being sold on the market that come from the Chesapeake Bay meet National Shellfish Sanitation Program standards and are not coming from the closure area on the Potomac River. Each bushel of Maryland-harvested oysters currently being sold includes a tag indicating where they were harvested from and are tracked to ensure food safety standards are met.
“The Potomac has long supported healthy oysters and shellfish—and that remains true today,” said Potomac Riverkeeper Network President Betsy Nicholas. “Our watermen are harvesting well downstream of the spill, and both the data and the science point toward a near-term return to normal operations. While there is still serious work ahead at and around the spill site, the conditions further downstream are encouraging.”
Following the precautionary closure, a sewage bypass was installed to limit additional discharge. By the time the water traveled 60 miles downstream, bacteria levels continued to meet public health standards, water testing confirmed.
The Maryland Department of the Environment also collected water samples in the Potomac River in Prince George's and Charles counties; results show bacteria levels would meet water quality standards for recreational contact. The department will continue sampling at those locations in addition to locations near the spill site in Montgomery County.
“The magnitude of this sewage spill will require diligence and continued monitoring, but the good news is that the recent water quality results indicate that shellfish harvesting is safe in the Potomac River,” said University of Maryland Center for Environmental Science Provost Dr. Bill Dennison.
More information and detailed sampling data is available on the Maryland Department of the Environment’s Potomac Interceptor update website - mde.maryland.gov
