THURMONT, Md. — For the time being, Frederick County Health officials are recommending that no one swim at Cunningham Falls State Park.
On Friday, lab tests confirmed concentrations of a blue-green algae called Microcystis, from the South Beach section of the park.
The natural algae sometimes pops up in Maryland's Chesapeake Bay and fresh waters when rich in nutrients.
It can be harmful when producing toxins or reaching high concentration levels.
Microcystin can cause gastroenteritis and liver damage.
Visible signs can be bright green waters, or a surface scum that looks like green paint.
In the event contact is made, simply wash off with fresh water. See a doctor if any skin irritation persists.
Pets and livestock should be kept away in areas showing signs of Microcystis, although pets aren't likely to be harmed by ingesting small amounts of water.
Water quality testing will continue at the location until levels are lowered.