Pathogen Testing

Stream Monitoring


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Most people know it can be unsafe to drink unfiltered water out of a stream or lake, even if the water is visibly clear. This is true almost anywhere, including Adams County. Places where public swimming is encouraged are required to test the water to make sure it isn’t overly contaminated. But in Pennsylvania we have many waterways—more than 1,000 miles in Adams County alone—and most of them are not tested regularly.

The Watershed Alliance has just wrapped up a water-testing program aimed at this issue. Thanks to a grant from the South Mountain Partnership, we sampled streamwater at 21 sites around the county this summer and tested them for harmful pathogens. We’re currently analyzing the results—stay tuned to see what we found out!

In the meantime, here’s the background: Many common animal pathogens are invisible to the eye, but can cause sickness in humans, sometimes even death. Generally, these pathogens come from inside the guts of animals like humans, cows, deer, etc. They get into the water mainly through feces, or from dead animals.
The usual way people become infected with pathogens is by ingesting contaminated water. However, some pathogens can enter your bloodstream through cuts or sores on your skin. People often get infected swimming in a polluted river or lake, especially during warm months.

In September 2021, we tested five locations, five times each. At two of them we found average pathogen levels that fell within the state’s acceptable range for recreational use. These were at the Conewago Creek at the Conewago Creek Campground just northwest of Arendtsville, and Swamp Creek at the first trail crossing from Strawberry Hill Nature Center.
At the other three sites we tested, we found average pathogen levels that were unsafe for human recreation. These sites were at Toms Creek in Carroll Valley Park, the Conewago Creek fly fishing area along Narrows Road, and Middle Creek at Gordon Road.
Here’s what we did this summer: Throughout the month of August our corps of volunteers took streamwater samples from 21 sites across Adams County where folks like to fish, wade, swim, or otherwise play in the water. We then had the samples analyzed for the presence of harmful pathogens. We’ll let you know soon what we found!
We’d like to acknowledge our partners and funders for this project: We’re working with Adams County Trout UnlimitedFriends of Toms Creek, and the Adams County Conservation District.
This project was financed in part by a grant from the Community Conservation Partnerships Program, Environmental Stewardship Fund, under the administration of the Department of Conservation and Natural Resources, Bureau of Recreation and Conservation. The grant was awarded through the South Mountain Partnership, with management oversight by the Appalachian Trail Conservancy.
We are a partner of the South Mountain Partnership, an alliance of organizations working to preserve and enhance the cultural and natural assets of the South Mountain Landscape in Central Pennsylvania. To learn more about the South Mountain Partnership, please visit