Unhealthy levels of fecal bacteria have been found in streams, rivers and swimming holes from Frederick to Ellicott City to Bel Air this summer, according to data gathered by the Chesapeake Bay Foundation.
The foundation collected samples this summer from 40 Maryland streams and rivers in Baltimore, Carroll, Frederick, Harford and Howard counties and in Baltimore City. Most tests were conducted after rainstorms, when waterways are at their most polluted because of runoff.
In one case, after almost an inch of rain fell Aug. 2, bacteria levels at least 400 times above safe levels were present in White Marsh Run.
In another, bacteria levels reached more than 300 times safe levels in Cascade Falls, a popular swimming hole in Patapsco Valley State Park, after a one-inch rainstorm July 5. People were swimming in the water when the sample was taken.
Thirty of the tested waterways were deemed unsafe for swimming after rain fell across the region June 16-17, from Carroll Creek in Frederick to the Sucker, Tiber and Hudson branches in Ellicott City to the Stony Run in North Baltimore and the Bird River in eastern Baltimore County.
The foundation posted all of the data on its website.
With the samples, the organization is pressing local governments around the region to do more to prevent polluted stormwater runoff from reaching waterways.
State and federal initiatives require the counties and Baltimore city to establish long term plans to reduce the acreage of paved surfaces that exacerbate runoff, and to use landscaping and other techniques to catch runoff before it runs into waterways.
"This isn’t an abstract problem," said Alison Prost, the foundation's Maryland executive director. "It puts the health of residents who swim, wade or come into contact with these waters at risk."
Local governments in each of the counties the foundation conducted tests "need to work aggressively to reduce polluted runoff, and ensure the health of their residents," she said.