PORT TOWNSEND — Gibbs Lake has been reopened for recreation after two consecutive weeks of test results showing a safe level of microcystin, a toxin created by blue-green algae.

The other East Jefferson County lake that had been closed because of high levels of toxins — Anderson Lake — remains closed for now because no lab results were available for anatoxin-a, a quick-acting nerve poison created by blue-green algae that has been found in high levels in the state lake for most of the summer.

Lab test results of samples taken from East Jefferson County lakes generally are available on Fridays for both anatoxin-a and microcystin.

But this week, results were received only for microcystin, with anatoxin-a results delayed, said Greg Thomason, Jefferson County environmental health specialist.

That leaves the status of Anderson Lake, which is in a state park west of Chimacum, unknown until anatoxin-a results are received from King County Environmental Labs early this week.

Since no anatoxin-a has been found in Gibbs Lake all season, “I think we are safe” in reopening the county lake in light of low levels of microcystin found there, Thomason said Friday.

Microcystin can cause skin irritation and nausea over the short term and liver damage if ingested over a long period of time.

Gibbs Lake, which is south of Port Townsend, had been closed Aug. 23 because tests of a sample from the lake found 19.4 micrograms of microcystin per liter of water — the highest level ever seen in Gibbs Lake in five years of testing for algae toxins.

T

he safety threshold for microcystin is 6 micrograms per liter.

The following week, the level had fallen to 1.2 micrograms per liter.

The county pubic health eepartment waits for two consecutive weeks of low test results before reopening a lake closed because of toxins.

On Friday, results found that the level remained at 1.2 microgram per liter.

“Gibbs came down for a second week in a row,” said Greg Thomason, Jefferson County environmental health specialist.

“We are going to go ahead and reopen Gibbs, but with a warning sign,” he said.

“

There’s still a scum there, still a heavy bloom.”

No microcystin was found in Lake Leland, north of Quilcene.

Caution signs remain posted there and at Crocker Lake, which is near the U.S. Highway 101-state Highway 104 intersection, because both lakes contain the types of blue-green algae that can suddenly begin to produce toxins.

Anderson Lake has been open only a few weeks this season because of levels of anatoxin-a high above the 1 microgram-per-liter safety threshold.

Microcystin levels usually are low in Anderson Lake.

The lake was opened the last Saturday in April for the start of the statewide lowland fishing season but was closed May 3 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.

Fishing in the lake can only be catch-and-release now, according to state law, 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.

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.

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Managing Editor/News Leah Leach can be reached at 360-417-3531 or at leah.leach@peninsuladailynews.com.