Montgomery Parks is asking Lake Needwood visitors to be cautious after elevated levels of a toxic substance were found in the 75-acre lake that borders Derwood and Rockville.
Water testing has revealed higher levels of microcystin, a toxin produced by some species of blue-green algae, according to a Montgomery Parks news release. Microcystin can cause harm to the liver of humans and pets if ingested, but typically does not negatively affect lake wildlife like ducks, frogs and fish.
Park officials are particularly concerned about dogs that are off-leash and may swim and/or drink from the lake, despite the park requirement that dogs always be leashed, the release said.
Boating and fishing will still be allowed at the lake, which is within Rock Creek Regional Park in Derwood. Swimming in the lake is prohibited at all times.
“We have posted signs around Lake Needwood and urge visitors to please pay attention to these precautions to avoid any harm from microcystin,” said Jai Cole, the natural resources manager for Montgomery Parks. “Portions of the lake may be contaminated for the rest of the season. We will continue to monitor and update signs when the warning is lifted.”
Lake visitors are urged to wash their hands thoroughly if they come in contact with the water; keep dogs on a leash and not allow them to drink or go in the water, and only eat properly cooked muscle meat of fish that are caught in the lake.
“We just want to be safe,” said Melissa Chotiner, the media relations manager for Montgomery Parks. “Better safe than sorry.”