Anderson Lake closed due to Anatoxin-A

Published 1:15 pm Friday, May 1, 2026

PORT TOWNSEND — The state Parks and Recreation Commission has closed Anderson Lake after monitoring by Jefferson County Public Health revealed dangerous levels of Anatoxin-A.

Water-based recreational activities such as fishing, boating and swimming are prohibited until the bloom dissipates and the toxin levels decline.

Anderson Lake State Park remains open for other activities, such as horseback riding, hiking, biking and birdwatching, but visitors should avoid the lake.

Anatoxin-A, sometimes called “very fast death factor,” is a potent neurotoxin produced by cyanobacteria that can cause sickness or death when ingested in even small amounts.

Samples of water taken from Anderson Lake on April 27 tested by the state Department of Ecology revealed Anatoxin-A concentrations of more than 2 times higher than the state’s recreational criteria allow.

Toxin levels for lakes in the state are posted at www.nwtoxicalgae.org.

Public Health has monitored lakes in Jefferson County since 2007, and Anderson Lake has been closed every year since then.

Although no human illness have been documented at Anderson Lake, the deaths of three dogs have been confirmed to be due to Anatoxin-A exposure from the lake.

Public Health also has been monitoring Lake Leland, Gibbs Lake and Crocker Lake weekly after heavy algal blooms were noted, and warning signs have been posted at those lakes.

Silent lake was observed in April, but no signs of algal blooms were noted.

For more information, call Environmental Public Health at 360-385-9444 or visit www.jeffersoncountypublichealth.org/723/Lake-Status.