DERWOOD, Md. (WJLA) - Montgomery County officials are warning residents, both human and otherwise, to avoid drinking from and swimming in Lake Needwood in Rock Creek Regional Park.
In a media release, the Maryland-National Capital Park and Planning Commission said the shallow lake recently tested positive for microcystin, a toxic substance created by blue-green algae. While the substance typically does not adversely affect wild animals like ducks, turtles, frogs and fish, if ingested, it can cause severe liver damage for both humans and pets.
On Friday, park rangers posted around 50 bright yellow signs along trails surrounding Lake Needwood, warning park-goers of the budding threat.
"I've seen little patches of it," Louisa MacCormack, a summer camp counselor, said.
On Wednesday, MacCormack chaperoned a group of 20 children, as they paddle boated across the popular man-made lake.
"When we noticed the sign, the first thing we said was, 'Keep your hands and feet and everything out of the water,'" MacCormack's fellow camp counselor Brian Morgan stated.
An M-NCPPC spokeswoman says this isn't the first time Lake Needwood has bred a dangerous toxin. Direct sunlight accelerates algae growth, and because the 75-acre body of water is mostly unshaded, levels generally peak during the height of summer.
"I was quite surprised," Montgomery County resident Jessica Stagg remarked. "It sounds really serious."
Stagg and her boyfriend, Mike Hamberger, came to Lake Needwood Wednesday with their border collie, Charlie, unaware of the toxin lurking in the water.
"She was like, 'Hey, he can't get in the water, he can't get in the water.' And I was like, 'Why?' And she was like, 'Come read this sign,'" Hamberger said of his observant girlfriend.
So far, park officials have not suspended kayak, canoe, paddle boat or rowboat rentals, but they say extra care should be taken with hand washing. Fishing is also continuing, however, fishermen are advised to cook their catch, such as bass, catfish, trout and bluegill, extra thoroughly. Park rules state dogs should always be leashed, and swimming is never allowed for humans.
"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," an M-NCPPC spokeswoman concluded.