The King County Department of Natural Resources test results for samples collected in January show microcystin levels to be within the guidance limits for recreational activities in the lake.
The current closure started in late summer in response to test results from samples collected that showed the highest levels of microcystin, a toxin produced by cyanobacteria commonly known as blue-green algae, than had ever been recorded at the lakeshore. The lake had remained clear for an extended time following an alum treatment in 2004, which lasted more than eight years, as expected.
Past experience has shown that the lake will most likely continue to suffer toxic algae blooms and recreational closures during late summer and fall 2015 if the lake is not treated early in the year.
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. Lake visitors are reminded to keep in mind that the cyanobacteria (blue green algae) may show up at any time of the year, so always be alert and if in doubt stay out!