PORT TOWNSEND — Anderson Lake was closed to fishing Friday because of a high concentration of a potent neurotoxin created by blue-green algae.
“The message is ‘no recreation in the lake,’” said Mike Zimmerman, Anderson Lake State Park’s manager, who posted red closure signs at the lake Friday.
“Stay out of it,” he said.
Aside from the lake, the 410-acre park between Chimacum and Port Hadlock is open.
Hiking, horseback riding and biking — all recreation not related to the 70-acre lake — are permitted in Anderson Lake State Park.
The concentration of the neurotoxin anatoxin-a in the lake was 2.7 times the proposed safe recreational limit, according to test results received Friday, said Greg Thomason, Jefferson County environmental health specialist.
The risk to both people and animals from the algae-produced 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 to close the lake to fishing and swimming, Thomason said.
Test results showed concentrations of 2.67 micrograms per liter. The recreational limit is 1 microgram per liter.
The lake also has a visible algae bloom.
“We’ve got a pretty scummy bloom on the whole lake,” Zimmerman said.
Zimmerman said that, based on past experience, the lake probably won’t be reopened for the rest of the fishing season, which extends through October.
The lake has to test clear of toxins for two weeks before its status can change.
“Fortunately, there are a lot of other lakes around,” Zimmerman said.
The status of other East Jefferson County lakes tested this week remains 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.
A caution sign means toxins may be present in a lake. Fishing is permitted, and fish may be eaten after they have been cleaned and the guts discarded.
Anderson Lake has been plagued with summertime closures because of high concentrations of toxins since Memorial Day 2006, when two dogs died after drinking lake water with a heavy concentration of anatoxin-a.
In April 2010, Anderson Lake was opened for fishing for the first time since 2008 but was closed three weeks later.
“We did get 41 days of fishing this year. We’re glad for that,” Thomason said.
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.
They know that calm water, warmth and a high concentration of such nutrients as phosphates, a chemical commonly found in lawn fertilizers, can encourage a bloom of algae.
But why it can suddenly become deadly — “that’s the big question that everybody wishes they knew the answer to,” Thomason said.
For instance, Silent Lake, a small lake on the Toandos Peninsula, has developed an algae bloom.
“And the dominant algae is anabaena, but we don’t have any toxins in the lake,” Thomason said.
“For some reason, it’s not producing toxins. We don’t know why.”
Another toxin historically found in East Jefferson County lakes is microcystin, which can damage the liver.
Microcystin has not been detected this season in the county’s lakes.
Both Leland and Silent lakes tested below detectable levels for anatoxin-a and microcystin.
Microcystin was below detectable levels in Gibbs Lake, while anatoxin-a was barely detectable.
Anyone who observes an algae bloom at a lake is urged to phone the Jefferson County Public Health Department at 360-385-9444.
For more information about lake quality in Jefferson County, visit the environmental health website at http://tinyurl.com/6z64ofy.
No toxic blue-green algae has been reported in Clallam County, where health officers do not test for toxins, instead visually monitoring lakes for signs of algae bloom.
Algae blooms in Clallam County lakes should be reported to the Clallam County Department of Health and Human Services’ environmental health division at 360-417-2258.
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Managing Editor/News Leah Leach can be reached at 360-417-3531 or leah.leach@peninsuladailynews.com.
