City of Snohomish - NewsFlash

Posted on: November 1, 2017

Blackmans Lake Caution - Update

Warning Sign Algae

Blackmans Lake Toxic Algae WARNING Continues

Blackmans Lake is experiencing blue-green algae scum near the shorelines. The scum looks like green paint on the surface of the water near the shorelines and green clumps throughout the lake. Samples were collected on Tuesday, October 31st at the public boat launch. Sample results are above the recreational standard of 6 ppb (parts per billion) for microcystins, a liver toxin, set by the Washington Department of Health. The WARNING signs are posted at Ferguson Park and Hill Park.

WARNING signs advise lake users of the potential for exposure to toxic algae. It is especially important to avoid areas of algae scum because this is where the toxin levels are the highest. Also be aware that lake conditions and locations of scum can change from day to day.

The WARNING signs advise the following:

· Do not swim in the lake

· Do not drink lake water

· Keep pets away from the lake

· Clean fish well and discard guts

· Avoid areas of scum when boating

Toxic algae can cause serious illness in humans who drink or play in affected waters. Pets that drink the water are at particular risk. If you or your pet are exposed to a blue-green algae bloom and have unexplained sickness or signs of poisoning, call your health care provider or veterinarian.

Please visit to see up-to-date testing information, sign up for alerts, and answers to commonly asked questions (choose the “Toxic Algae” link from the main page).

Blackmans Lake Algea

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