A thick algae bloom was found infesting Gibbs Lake last week, prompting a public health downgrade in its status from “caution” to “warning.”
Although tests show that both anatoxin-a and microcystin, a liver toxin, are below safe levels in Gibbs Lake, the algae that is reproducing in the lake is known to be of a type that can suddenly begin creating toxins.
They aren’t producing a dangerous level of toxins now but could begin doing so at any time, said Greg Thomason, Jefferson County environmental health specialist, Friday.
Testing is always a week behind the fact, since samples are taken Mondays and results are received from King County Environmental labs Fridays.
“There’s a really thick bloom of algae there,” Thomason said. “It looks worse than Anderson Lake.”
Only Anderson Lake closed
Thick blooms of blue-green algae infest three Jefferson County lakes, but only one — Anderson Lake — is so poisoned with algae toxins that it is closed to all water recreation, including fishing.
The level of toxins in Anderson Lake, which was closed June 10, is decreasing, but it’s still too dangerous to go in the water, according to Friday’s test results of samples taken last Monday from the lakes.
Those test results showed the lake contained 2.3 micrograms of anatoxin-a, a powerful neurotoxin, per liter of water. The safe level is 1 milligram per liter.
“Anderson continues to come down,” said Greg Thomason, Jefferson County environmental health specialist, Friday. “It’s still double the safe level.”
The closure doesn’t affect the 410-acre state park surrounding the 70-acre lake.
The park, which is between Chimacum and Port Hadlock, remains open for hiking, horseback riding, biking — all recreation not related to the lake.
Other lakes
A warning sign remains posted at Lake Leland, north of Quilcene, because of a heavy algae bloom.
No toxins were found in Silent Lake on the Toandos Peninsula, which is posted with a caution sign because of a light-to-medium bloom of toxin-producing algae.
Sandy Shore Lake, which is south of Port Ludlow near state Highway 104, remains clear.
Gibbs is the only lake of the five that the county health department routinely tests that shows any microcystin at all, Thomason said.
“In fact, microcystins levels came up this week, although they are still below safe levels,” he said Friday.
Anderson Lake toxin readings have been decreasing since a June 24 test result showed 1,112 micrograms per liter of anatoxin-a, the highest level since 2008, when the lake set a world record — still unbroken — of 172,640 micrograms per liter.
Before state parks authorities would consider reopening the lake, tests results would have to be below the threshold for safety for at least two consecutive weeks.
It’s safe to eat properly cleaned fish from Leland, Gibbs and Silent lakes, but no one should swim in the lakes or drink the water.
Anyone who observes an algae bloom at a Jefferson County lake is urged to phone 360-385-9444 and inform the public health department, which posts information about lake quality 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, they visually monitor lakes for algae blooms.
Algae blooms in Clallam County lakes should be reported to the 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.