News Flash

City of Snohomish - NewsFlash

Posted on: September 17, 2020

Blue-Green Algae Bloom

Toxic Algae

Blackmans Lake is experiencing a potentially toxic bloom of blue-green algae.

The bloom looks like bright blue clumps floating in the water which sometimes accumulate as a scum along the lake shoreline. A sample was collected and analyzed for toxins this week. WARNING signs were posted at the public access sites. The signs provide guidance for lake recreation (see sign below). It is especially important to avoid areas of algae scum because this is where the toxin levels are the highest.

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 learn more about toxic algae and see the most recent testing results.

Toxic algae WARNING sign multi-language

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