PORT TOWNSEND — Anderson Lake was closed to fishing today for the first time this season.
The concentration of anatoxin-a, a potent neurotoxin, was 2.7 times the proposed safe recreational limit, according to test results received today, said Greg Thomson, Jefferson County environmental health specialist.
Test results show concentrations of 2.67 micrograms per liter. The recreational limit is 1 microgram per liter.
The risk to both people and animals from the toxin, which can cause convulsions and even death by respiratory paralysis, was great enough to prompt State Parks to act immediately upon the county public health department’s recommendation, and closure the lake to fishing and swimming, Thomason said.
“Lab tests indicate [the concentration of toxin] has doubled since last week,” said Mike Zimmerman, Anderson Lake State Park’s manager, who posted red closure signs at the lake today.
“The message is ‘no recreation in the lake,’” Zimmerman said. “Stay out of it.”
Aside from the lake, the 410-acre park between Chimacum and Port Hadlock is open. Activities within Anderson Lake State Park that are not related to the lake — such as hiking, horseback riding and biking — remain permitted.
The status of other lakes tested in East Jefferson County this week remain unchanged.
Caution signs remain at Gibbs Lake in Chimacum; Lake Leland, north of Quilcene and south of U.S. Highway 101; and Silent Lake north of Coyle.
Anderson Lake had opened for the fishing season on April 30.
The lake has been subject to summertime closures since Memorial Day 2006, when two dogs died after drinking lake water with heavy concentration of anatoxin-a.
The toxin is created by blue green algae. In the case of Anderson Lake, the algae bloom is made up predominately of aphanizomenon and anabaena algae, both of which are known to sometimes create toxins.
Researchers aren’t sure why blue-green algae, a common water plant, suddenly will begin to make toxins.
A bloom is now visible on Anderson Lake.
