CHIMACUM — State parks has closed Anderson Lake to fishing because of high levels of a potent nerve toxin.
A sample taken from the lake between Port Townsend and Chimacum on Monday was found to have a 9.5 micrograms per liter of anatoxin-a, said Michael Dawson, water quality manager for Jefferson County Pubic Health, in a press release on Thursday.
Testing, which resumed in April after the last of the season was done in November, found low levels of anatoxin-a in the lake on April 29. Since then the toxin created by blue-green algae has blossomed to an amount above the recreational threshold of 1 microgram per liter.
Anatoxin-a can cause illness and death in human and animals within four minutes of being ingested, according to health authorities.
State Parks has closed the lake for recreation including fishing, boating, and swimming. Visitors also are urged to keep pets out of the water. The 410-acre Anderson Lake State Park remains open to hiking, bicycling, horseback riding and other recreation.
Blooms also have appeared this year at Gibbs Lake and Sandy Shore Lake, but toxins have not been detected at either of those lakes so far in 2019, Dawson said.
Routine testing of the lake began in 2007 after two dogs died in 2006 after drinking Anderson Lake water. Since then, the lake has been forced to close every year due to toxins, sometimes for much of the year. In 2008, the lake set a worldwide record for the highest levels of anatoxin-a ever recorded, hitting 172,640 micrograms per liter.
Blue-green algae, like that found in Anderson Lake, are naturally occurring and found in freshwater lakes across the state. However, sometimes these blooms produce toxins that are released into the water, though why this happens isn’t fully understood. Hot weather tends to encourage the growth of algae and thus poses the greatest risk of toxins forming.
Toxins have not been found in Clallam County lakes.
To check on lake status in Jefferson County, see https://tinyurl.com/PDN-jeffcolakestatus.
