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City of Snohomish - NewsFlash

Posted on: July 25, 2022

Toxic Algae at Blackmans Lake

Toxic Algae Alert

Blackmans Lake is experiencing a potentially toxic bloom of blue-green algae. The bloom looks like bright green paint floating on the surface of the water.


WARNING signs will be posted at Hill and Ferguson Parks and provide guidance for lake recreation (see below sign). It is especially important to avoid areas of algae scum because this is where the toxin levels are the highest. Toxic Algae 2022

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. 

You may also visit to learn more about toxic algae and see the most recent testing results.

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