Potentially high levels of blue-green algae, also known as cyanobacteria, in Lake Needwood and Lake Frank in Rockville have Montgomery Parks officials warning residents and dog owners to avoid contact with the two bodies of water in Rock Creek Regional Park.
“As a precautionary measure, we are alerting the public of the risks associated with potentially high levels of cyanobacteria in these lakes,” Matt Harper, natural resources manager with Montgomery Parks, said in the Thursday release. “While we await the toxin testing results, we urge people to keep their dogs on leash and ensure they are not allowed contact with the water.”
Cyanobacteria can produce a toxin called cyanotoxins, or microcystin, which is a “potent liver toxin and possible human carcinogen,” according to the U.S. Environmental Protection Agency (EPA). Cyanotoxins can kill livestock and pets that drink affected water.
Water samples from the lakes are being evaluated by the Maryland Department of the Environment to determine if the levels of algae are harmful, according to the release.
Parks officials have observed discolored water and algal mats in portions of both lakes, typical visual indicators of an algal bloom, the release said.
Algae blooms occur when there are warm temperatures and high levels of nutrients in the water and can also be identified from “floating mats of decaying, bad-smelling and gelatinous scum” in bodies of water, according to the EPA.
Cyanobacteria are naturally occurring algae but when grown in excess (a bloom), can produce microcystin toxins that are harmful to humans and pets, according to the release. Montgomery Parks’ primary concern with the high levels of cyanobacteria is off-leash dogs that may swim and/or drink from the lake, the release said.
Dogs are already prohibited from swimming in park lakes, but the department is urging visitors to take the following precautions:
- Avoid direct contact with water while boating or fishing (swimming is always prohibited in lakes);
- Keep dogs on leash (per park regulations), and do not allow them to drink or be in contact with the water or algal mats accumulating on shorelines;
- If your pet has been in contact with lake water or algae, rinse fur with clean water and seek veterinary care if you are concerned;
- Wash hands thoroughly before eating, drinking or smoking if you have come in contact with the water; and
- Only eat properly cooked muscle meat of fish.
For now, recreational fishing and boating at the lakes will remain open, according to the release.
Rock Creek Regional Park manager David Quintanilla said signs about the potential risk of elevated microcystin in the water have been posted around the two lakes and along trails that access the lakes.
“Portions of both lakes may be contaminated for the rest of the season. We will continue to monitor and remove signs when the warning is lifted,” Quintanilla said in the release.