Green Lake Now Deemed Safe – Toxic Algae Could Return

As the weather cools, King County tests on patches of algae scum in Green Lake are showing a decrease in microcystin, a form of blue-green algae that can be toxic and caution signs can now come down. Results from samples have shown levels well below the state guidance level of 6.0 ug/L for three consecutive weeks, so the lake is considered safe for water activities and animals.

You May See Caution Signs Posted at the Lake if Algae Returns

Caution signs are posted around the lake when there is potential hazard from exposure to the algae. King County Department of Health and Seattle Park Department make the determination to post warning or closure signs at the lake. Signs can be removed when there has been a series of weekly tests below the guidance level.

algae1-2011sepPhoto by Karen Schurr

Algae blooms are notorious for being very patchy – high levels in one area and low levels in another close by area. Thus, health agencies always recommend avoiding any areas that have dense concentrations of scum. It is always good practice to keep dogs from entering and drinking the water where the green scum is present. Be especially careful if you notice there is a bright green scum on the water.

We urge you to join with other Friends of Green Lake at our monthly meetings as we learn more about algae and the lake. See meeting notices elsewhere on this page.

If you have questions or comments or observations you can email FOGL President Garet Munger.
AlgaeBloom-2012oct2Photo by Gayle Garman