PORT TOWNSEND — Toxins are at safe levels in both Anderson and Gibbs lakes, the most recent test results show, but both lakes will remain closed for at least one more week.
“We have to have two weeks of results below warning levels before we can reopen” in the case of a county lake such as Gibbs, or recommend to state rangers the reopening of Anderson Lake, said Greg Thomason, Jefferson County environmental health specialist.
Only 0.61 micrograms of anatoxin-a per liter of water was in test results Friday of a sample taken Monday from Anderson Lake, west of Chimacum.
The lake had been closed Aug. 23 — after having been reopened for fishing and other recreation less than a week earlier — because of a level of 4.9 micrograms of anatoxin-a, a powerful nerve poison secreted by blue-green algae.
The safety threshold for anatoxin-a, which can cause paralysis and stop breathing, is 1 microgram per liter.
The lake has been open for recreation only for a couple of weeks this season.
It opened the last Saturday in April for the start of the statewide lowland fishing season.
But it closed May 3 because of elevated toxin levels before briefly reopening last month.
Mike Zimmerman, a State Parks ranger who oversees Anderson Lake State Park, had said after the most recent closure of the lake that he did not know if it would be reopened this season, even if the toxin level fell and stayed low.
“It’s not really doing the visitors a service if we only open for five or six days, then have to close,” Zimmerman said then, adding that the season was drawing to a close.
The lake became a catch-and-release-only lake beginning Saturday and the entire state park will close Oct. 31.
For now, however, the 410-acre state park around the lake remains open for recreation. A Discover Pass is needed to park there.
“Microcystin levels levels dropped way, way down” in Gibbs Lake, test results showed, from 19.4 micrograms per liter on Aug. 23 to 1.2 micrograms Friday, Thomason said.
The county lake south of Port Townsend was closed after the high reading — the highest level ever seen in Gibbs Lake in five years of testing for algae toxins.
The safety threshold for microcystin, another toxin created by blue-green algae, is 6 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.
Microcystin tends to rise and drop more dramatically than anatoxin-a, Thomason said.
“We see more extremes with microcystin than anatoxin. I don’t know why that is,” Thomason said.
“Anatoxin seems to build more slowly and drop more slowly.”
A trace of micrcystin was found in Anderson Lake.
No anatoxin-a was discovered in Gibbs Lake.
Neither anatoxin-a nor microcystin could be detected in a sample from Lake Leland, north of Quilcene.
But the lake has a heavy bloom of algae.
“If scum starts to show up and the bloom gts thick, be careful,” Thomason said.
Caution signs remain posted at Leland and Crocker, which is near the U.S. Highway 101-state Highway 104 intersection, beacuse both lakes contain the types of blue-green algae that can suddenly begin to produce toxins.
Researchers know that warm weather fuels algae growth when sufficient nutrients such as phosphates are present, but they don’t understand what sparks the production of toxins from some species.
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.
