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Harmful Bacteria Discovered in Freshwater Lakes, Streams Across MD


Water tests in Harford, Frederick and Howard counties have revealed that some lakes and streams contain high levels of harmful bacteria that may indicate the presence of fecal matter.

According to a July 16 Baltimore Sun article, researchers from the Chesapeake Bay Foundation, Harford Community College, Hood College and Howard Community College discovered the water tested positive for enterococcus bacteria. This bacteria typically indicates the presence of human or animal waste, and could have come from a leaking septic system or from livestock.

Levels of enterococcus significantly surpassed the EPA’s recommended limits for water safety, especially in the days immediately following a rainstorm. Glade Run, a local freshwater lake, tested positive for more than 200 times the EPA’s safety limit for enterococcus. At Kilgore Falls, a popular swimming site in Harford County, the bacteria was present at 50 times the recommended safety limit.

“I think it is concerning that over all three counties, we rarely see a number within the range the EPA considers to be swimmable,” said Drew Ferrier, director of the coastal studies program at Hood College in Frederick.

This information is particularly concerning when the average family of four will use approximately 400 gallons of water per day. While the enterococcus bacteria isn’t technically dangerous in itself, the bacteria is often an indicator of other bacteria that can be harmful. When ingested, this water can lead to gastrointestinal problems such as diarrhea — and is most harmful to young children, whose immune systems aren’t fully developed.

“It’s not life-threatening by any means, but it could be nasty,” said Tom Zolper, a spokesman for the Chesapeake Bay Foundation. “If you think back in the Middle Ages when sewage was dumped in the street, that was the thing that made people commonly sick — the mixing of fecal of matter where people are living.”

For families who swim at public water sources, it’s important to be vigilant against over-exposure to the bacteria. Zolper advised Maryland residents to limit their exposure to these water sources, especially within 48 hours of a rainstorm. Additionally, it’s important to avoid ingesting the water and to rinse off after swimming, he said.

Researchers will continue to monitor water bacteria levels at these 18 sites throughout the rest of the summer.

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