PORT TOWNSEND — Anderson Lake is closed again, after having been reopened for fishing and other recreation less than a week ago, and Gibbs Lake will be closed this morning.
Both closures are of because of elevated levels of toxins created by blue-green algae.
The lake in Anderson Lake State Park, which is west of Chimacum, was closed to all recreation Thursday, said Mike Zimmerman, a State Parks ranger who oversees Anderson Lake State Park.
Gibbs Lake, a county lake south of Port Townsend, will be posted with a closure sign this morning, said Greg Thomason, Jefferson County environmental health specialist.
Both closures are in response to preliminary test results received Thursday. The tests are of water samples taken Monday.
Final results are expected today.
Anatoxin-a, a quick-acting nerve poison, was found to have climbed to nearly five times the safety threshold in Anderson Lake: 4.9 micrograms per liter.
The safety threshold for anatoxin-a — which can cause paralysis and stop breathing — is
1 microgram per liter.
Microcystin was found to be at the highest level ever seen in Gibbs Lake: 19.4 micrograms per liter of water, which is “over three times the warning level” of 6 micrograms per liter, Thomason said.
It’s also more than three times the highest level ever seen before in five years of testing: 6.8 micrograms per liter.
Microcystin can cause liver damage if ingested over a long period of time; in the short-term, it can cause skin irritation and nausea.
Gibbs Lake also has a thick bloom and scum over the entire lake, Thomason said.
“The lake is closed,” said Lori Bond, office assistant at Anderson Lake State Park, on Thursday morning.
The closure sign was posted at Anderson Lake shortly after 3 p.m., and a few people were observed on the lake earlier in the day.
A ranger told those on the lake to leave at 3 p.m.
The closure sign was to be erected soon afterward, said Zimmerman, park manager for the Fort Flagler area.
Anderson Lake will be monitored weekly until the end of the season at the end of October.
If toxin levels fall to a safe level, it is possible the lake could be reopened, Zimmerman said, though he said he “is not leaning in that direction.”
“It’s not really doing the visitors a service if we only open for five or six days, then have to close,” Zimmerman said.
The lake will become a catch-and-release-only lake beginning Sept. 1, and the entire state park will close Oct. 31.
“Some of the recreation is going to be limited just by wildlife rules anyway,” Zimmerman said.
The 410-acre park surrounding the lake remains open. A Discover Pass is needed to park there.
The lake was closed on the recommendation of Jefferson County Public Health, which collects samples for the weekly tests for level of toxins created by blue-green algae.
The lake has been open for recreation only a couple of weeks this season.
It was opened the last Saturday in April for the start of the statewide lowland fishing season but was closed May 3 because of elevated toxin levels.
The level of anatoxin-a reached a high of 619 micrograms per liter in Anderson Lake in early July.
The lake was reopened last Friday after two consecutive weekly tests showed the level of anatoxin-a to be below the safety threshold.
Final test results “are almost always identical to the preliminary results,” Thomason said.
“But even if they are off a little bit, it’s still well above the warning level of 1 microgram per liter.”
Preliminary results showed other lakes tested in East Jefferson County to be safe, Thomason said.
Researchers know that warm weather fuels algae growth when sufficient nutrients such as phosphates are present.
They don’t understand why some species of blue-green algae will suddenly begin to produce toxins.
No toxic blue-green algae has been reported in Clallam County, where health officers do not test for toxins; instead, they visually monitor lakes for signs of algae bloom.
Report algae blooms in Clallam County by phoning 360-417-2258.
Report algae blooms in Jefferson County by phoning 360-385-9444.
For more information about lake quality in Jefferson County, visit the environmental health website at http://tinyurl.com/6z64ofy.
________
Managing Editor/News Leah Leach can be reached at 360-417-3531 or at leah.leach@peninsuladailynews.com.
