SILVER SPRING, Md. (WUSA9) -- Montgomery Parks, part of the Maryland-National Capital Park and Planning Commission want residents and visitors to be cautious about their activities at Lake Needwood in Rock Creek Regional Park.
According to officials, testing found elevated levels of Microcystin, a toxic substance produced by blue-green bacteria known as cyanobacteria.
Officials say the algae can cause serious harm to the liver of humans and pets if ingested.
Montgomery Parks officials are asking visitors to keep dogs on leash, keep them from drinking or going into the water. Visitors should also not swim in the lake. If you come in contact with water, you should wash you hands thoroughly. Additionally, officials say you should only eat "properly cooked muscle meat of fish that are caught in the lake."
Officials tell us that boating and fishing will remain open at the lake.