MDE: Flood Sewage Unlikely to Blame for Potomac’s Bacteria Surge; Swimmers Still Advised to Take Precautions

This week, the Maryland Department of the Environment (MDE) concluded that sewage leaks from May’s western Maryland floods are not a primary driver of elevated E. coli readings in downstream Potomac River counties. Instead, summer’s frequent downpours and higher water temperatures continue to fuel bacteria growth, prompting state officials to call for safe-swimming practices—especially after rain events.

According to a statement emailed to Radio Free Hub City, MDE’s Water and Science Administration spent the past several days coordinating with Allegany County Public Works, local health departments and the Maryland Department of Health to review sampling data and infrastructure reports. Their analysis found no significant evidence of lingering sewage discharges into the river from flood-damaged systems. While isolated leaks were reported in May, follow-up inspections and monitoring showed they were minor and swiftly contained.

State experts emphasize that this season’s bacteria upticks align with a pattern seen across natural waterways during wet, warm weather. Heavy rains wash animal and agricultural waste, pet droppings and soil into streams, delivering a cocktail of bacteria downstream. Once in the river, elevated temperatures help bacteria reproduce and survive longer, raising the risk for those who enter the water.

In response to these conditions, MDE yesterday released guidance on safe water contact during and after wet weather, urging residents to avoid swimming within 48 hours of heavy rainfall and to heed simple hygiene steps such as showering immediately after leaving the water. Their full set of beach and river safety tips is available on the MDE website.

Meanwhile, Upper Potomac Riverkeeper’s shoreline tests continue to show geometric mean bacteria levels above the 126 MPN limit at nearly all monitored boat ramps and parks, even when individual samples remain under the 410 MPN single-sample threshold. The Riverkeeper organization cautions that while a low single reading can be reassuring, it does not override a history of higher measurements—and still-classified “medium” or “high” risk sites demand vigilance, especially for children and swimmers with open wounds or weakened immune systems.

To protect yourself and your family, avoid areas where storm drains or visible pipes discharge into the river, steer clear of water that appears cloudy or discolored, and don’t swallow river water. Keep pets out of the water after storms, and cover any cuts with waterproof bandages if contact is unavoidable. After every outing, take a thorough shower and wash your hands before eating or touching your face.

For the latest test results, residents can check the Swim Guide app, and report any unsafe conditions to local health officials or park managers. By staying informed and following these precautions, river users can enjoy a safer summer on the Potomac.

Article by multiple contributors, based upon information from the Maryland Department of the Environment Water and Science Administration, Washington County Government Emergency Management, and Upper Potomac Riverkeeper monitoring reports

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