PORT TOWNSEND — Anderson Lake remained closed — and the status of other East Jefferson County lakes was unchanged — after the most recent test results were received last week.
“Things are holding about the same as they were last week,” said Mike Dawson, Jefferson County environmental health specialist, on Friday.
The level of anatoxin-a, a quick-acting nerve poison that can cause convulsions and stop breathing, rose again last week in Anderson Lake, from 17.5 micrograms per liter of water the week before to 27.6 micrograms per liter this week.
The safety threshold is 1 microgram per liter.
The 410-acre Anderson Lake State Park, which surrounds the lake, remains open for recreation.
The lake within the park, which is between Port Townsend and Chimacum, was closed May 3, only a few days after it had opened for the start of the trout-fishing season the last Saturday in April.
Toxins created by blue-green algae have prompted closures of the lake since 2006, when two dogs died Memorial Day weekend after drinking lake water.
Last week, a moderate bloom remained on Anderson Lake, and slight blooms could be seen on Leland and Gibbs lakes.
Only a trace of anatoxin-a was found in Lake Leland, north of Quilcene, with none detected in Gibbs, south of Port Townsend.
Microcystin test
No microcystin — another algae-produced toxin common in East Jefferson County — was detected in Anderson, Leland or Gibbs lakes.
Microcystin can cause skin irritation and, if ingested over a period of many years, can result in liver failure.
Samples are taken each Monday, and results are announced by Friday after testing at King County Environmental Labs.
Caution signs remain posted at Leland, Gibbs and Crocker lakes because they contain species of algae that are known to sometimes produce toxins.
Researchers know algae flourishes in warm temperatures when sufficient nutrients, such as phosphates, are present, but they don’t understand why some species of blue-green algae begin to produce toxins, nor what makes them increase.
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.
A Discover Pass — which is $10 for one day or $30 for an annual pass, and which can purchased at state parks — is needed to visit state parks.
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.