Warning Signs Up at Green Lake! No Swimming, Wading, Wet Water Boating

On September 12, 2014 Seattle Park Department posted signs around Green Lake advising visitors that the lake is closed to wading, swimming, and wet water boating activities. The lake remains open to fishing (though fish should be thoroughly cleaned) and boating in stable boats. And the lake remains open for Green Lake Crew to continue their training on the lake.

This closure, which remains in effect as of this date October 24, 2014, was in response to test results from samples collected on September 11, 2014, that showed a high level of microcystin, a toxin produced by cyanobacteria commonly known as blue-green algae growing in the lake. Earlier advisory signs had been posted on August 22, only advising visitors of the potential hazard from the green scum and to “Be Alert — If in Doubt Stay Out.”

Milfoil and Algae Scum at Green Lake.

The King County Department of Natural Resources is continuing weekly sample collection and analyses for the lake. The most recent test results for samples collected on September 26 show microcystin levels to be well in excess of the guidance limits for recreational activities in the lake. Test results for Green Lake are posted at the nwtoxicalgae.org site.

This site lists historical test results as well as the most recent. Scroll to the bottom of the page for the most recent testing. The page is updated as testing of samples is completed. Sample collection from Green Lake is currently being conducted on a weekly schedule. Health Department guidelines require that closures remain in effect until testing shows that the microcystin level is below the guidance level of 6.0 ug/L for three consecutive weeks. Visitors to Green Lake are advised to heed the warning signs and keep yourself, children, and pets out of the water. Additionally it is wise to keep in mind that the cyanobacteria (blue green algae) may show up at other times during the year. It is wise to always heed the caution to: Be Alert and if in Doubt Stay out.
[tribulant_slideshow gallery_id=”18″]Photos courtesy of Garet Munger and Karen Schurr