CHIMACUM — Washington State Parks has closed Anderson Lake to recreation after high levels of the potent nerve toxin anatoxin-a were detected in a water sample.
The closure includes fishing, boating and swimming. Visitors are also urged to keep pets out of the water, according to a Jefferson County Public Health press release issued Monday.
Anatoxin-a can result in illness and death in people and animals.
A bloom of bluegreen algae, or cyanobacteria, produces the toxin. The bloom in the lake near Chimacum contains several toxin-producing species of algae, including Dolichospermum, formerly Anabaena.
Above safe level
The water sample was taken from the lake May 29 and contained a toxin level of 112 micrograms per liter, well above the state recreational criteria of 1 microgram per liter.
The rest of Anderson Lake State Park remains open for hiking, biking and horseback riding.
Algae blooms have also appeared this year at Lake Leland and Gibbs Lake, but toxins have not been detected at either of those sites this year.
Jefferson County Public Health has monitored local lakes for cyanobacteria since 2007. Anderson Lake has had closures every year since monitoring began.
In 2017, the state Department of Fish and Wildlife made changes to the fishing season at Anderson Lake to allow recreational fishing during the colder months when blooms are less likely to occur.
State Parks also opened the Anderson Lake gate on a Friday through Sunday schedule from November 2017 to this April. Although late season blooms kept the lake closed through fall 2017, early 2018 saw five consecutive months of open access.
To check the status of Jefferson County lakes and learn more about toxic cyanobacteria monitoring, visit the Jefferson County Public Health website at https://tinyurl.com/PDN-LakeStatus or call 360-385-9444.
For fishing seasons and regulations, see the Fish and Wildlife website at www.wdfw.wa.gov/fishing.
Information on visiting Anderson Lake State Park is available at https://tinyurl.com/PDN-ParkVisit.