CHIMACUM — Anderson Lake is closed to fishing and other recreation.
High levels of the potent nerve toxin anatoxin-a were detected in water samples taken from Anderson Lake on Monday, said Mike Dawson, water quality lead with the Jefferson County Public Health Department, today after results were received from King County Environmental Lab.
Upon the county’s recommendation, State Parks Ranger Mike Zimmerman, closed the lake to fishing, boating and swimming. People also are urged to keep pets out of the water.
The 410-acre Anderson Lake State Park around the lake remains open for hiking, biking and horseback riding.
“Visitors should be aware that the algae bloom at Anderson Lake is not very visible right now,” Dawson said.
“But don’t be fooled by the lack of a bright green scum; the toxin level is high.”
The toxin level in Anderson Lake was found to have climbed to 4.26 micrograms per liter, which is more than four times greater than safety threshold of 1 microgram per liter, Dawson said.
Anatoxin-a is produced by blue-green algae, also known as cyanobacteria, which occurs naturally but which can begin, for unknown reasons, to produce toxins.
Anatoxin-a is a quick-acting poison that can led to death in people and animals within 4 minutes if ingested in high doses.
The county public health department has seasonally monitored area lakes for blue-green algae since two dogs died after lapping water form the lake on Memorial Day weekend in 2006.
Monthly monitoring of Anderson, Gibbs and Leland lakes in East Jefferson County began in April of this year, with weekly toxin samples taken when blooms are present, Dawson said.
Anderson Lake was opened for recreational fishing on April 27 for the beginning of the state lowland lakes fishing season.
April results showed that the bloom at that time was dominated by Aphanizomenon, a toxin-producing species of blue-green algae, Dawson said.
Gibbs Lake and Lake Leland have had light blooms but only low levels of toxins so far in 2013, he added, saying that caution signs are up at Gibbs and Leland.
Researchers don’t know why some types of algae will suddenly begin producing toxins.
They know only that warmer weather and longer days tend to fuel the growth of blue-green algae when the lake contains enough nutrients, such as phosphorus.
Visitors need a Discover Pass — either $10 for a day or $30 for a year — to park within Anderson Lake State Park.
Passes can be bought at any state park, where hunting or fishing licenses are sold, by phoning 866-320-9933 or by visiting www.discoverpass.wa.gov.
Toxin-producing blue-green algae has not been spotted in Clallam County.
Report algae blooms in Clallam County by phoning 360-417-2258, while Jefferson County blooms can be reported at 360-385-9444.
For more information about Jefferson County lakes, see http://tinyurl.com/jeffersonlakequality or phone the office.
For fishing seasons and regulations see the state Department of Fish and Wildlife website, www.wdfw.wa.gov/fishing.
