Anyone planning an early fall boating or fishing trip to Lake Needwood should be sure to stay out of the water to avoid poisoning from a toxic algae.
The blue-green algae, also known as cyanobacteria, produces microcystin, a toxic substance that can cause severe liver damage if ingested, an alert posted by the park said.
Doug Redmond, a natural resources manager with the Maryland-National Capital Park and Planning Commission, said the park manager posted the alert late this summer after testing determined that the lake had enough toxins to be dangerous.
“The main problem is drinking the lake water,” he said. “Apparently, if one were to be exposed to high levels of the water for a long period of time, then exposure through the skin could be a problem, but the main thing that we’re concerned about is drinking.”
Dogs are in the greatest danger from the algae, Redmond said, especially if they swim in or drink the lake water. Cases of dogs dying from algae-related liver poisoning, although rare, have been reported in other places around the country.
Redmond said this isn’t the first time park officials have spotted the toxic algae in Lake Needwood.
“It seems to come back every year,” he said. “The one year that we didn’t have the problem was a couple years ago when the lake was dredged.”
That year, the water level was lower, Redmond said. Other than that, officials have found the algae in the lake every year for the past several years and they do not know of any effective way of getting rid of it yet.
Jay Apperson, spokesman for the Maryland Department of the Environment, said the blue-green algae blooms are more common during the warm summer months. Samples from Lake Needwood tested high for the toxin in late July this year.
“As the temperatures start to cool down, usually it will go away,” he said. “But it can be around till early November.”
Blue-green algae blooms are a worldwide concern, Apperson said, and have been reported in about six places in Maryland this year.
“There may be more, because there are so many private ponds and lakes,” he said.
Nitrogen and other nutrients from fertilizer carried into lakes and streams can encourage algae growth, Apperson said.
People can still fish and boat in Lake Needwood, although they should be sure to wash their hands well before eating, drinking or smoking, the alert said.
Visitors eating fish caught in Lake Needwood should only eat the muscle meat, since the toxin tends to accumulate in the internal organs, such as the liver, rather than in the muscles, Redmond said. The alert also advises people to cook their fish properly.
Swimming is prohibited at all times in Lake Needwood, and dogs must be kept on leashes.
For more information about the algae in Lake Needwood, call 240-372-9696. To report an algae bloom, call 1-877-224-7229.