PORT TOWNSEND — Jefferson County Parks and Recreation has closed Gibbs Lake for recreation after a high level of the toxin microcystin were detected in a water sample.
The sample taken from the lake south of Port Townsend on Monday showed a toxin level of 9.5 micrograms per liter, which is above the state recreational criteria of 6 micrograms per liter.
Microcystin can cause liver damage if consumed over a long period of time. It is produced by blue-green algae, also known as cyanobacteria.
Blue-green algae is a natural occurrence and is usually benign. At times, especially during warm weather, it can begin to produce toxins. Researchers still don’t know why.
The county lake has been closed for fishing, boating and swimming. Visitors also are urged to keep pets out of the water. Jefferson County Public Health has posted closure signs at lake access points.
Rest remains open
The rest of Gibbs Lake County Park remains open for hiking, biking and horseback riding.
The county public health department has monitored area lakes for blue-green algae seasonally since 2007. Monthly monitoring of Anderson, Gibbs and Leland lakes began in April of this year.
Anderson Lake near Chimacum was closed in May due to high levels of anatoxin-a, another toxin produced by cyanobacteria. Anatoxin-a is a potent nerve toxin that can kill within minutes.
A test Aug. 7 found that high levels of the toxin persist despite the lack of an algae bloom on the surface of the lake. Anderson Lake State Park remains open.
No toxins in Leland
No toxins were detected in Lake Leland north of Quilcene on Aug. 7.
Lake conditions can change rapidly, and lake status can change between samples, officials said.
The county health department urges recreationists to avoid contact with heavy blooms or scums.
Those who see algae blooms in lakes are urged to call 360-385-9444.
For more information about Jefferson County lakes, visit http://tinyurl.com/PDN-jeffersonlake status or call the office at 360-385-9444.
Toxin-producing blue-green algae has not been spotted in Clallam County. Report algae blooms in Clallam County by calling 360-417-2258.
