Sunday, June 26, 2022

Warmer Weather Could Mean Algal Blooms

Sledge-like green algae covers the surface of Big Lake Skagit.

Each year there is a possibility that our urban lakes may begin to grow harmful algae (cyanobacteria) blooms. Blooms can happen every year, especially in late summer and fall months, but it’s impossible to guess how each lake will be affected due to changing climate conditions and unpredictable nutrient runoff. Some lakes get regular blooms, some lakes rarely have blooms, and not every bloom is toxic. The only way to know if toxins are present is through laboratory testing. 

A photo gallery showing what toxic algae may look like can be found here.

When in doubt, STAY OUT

It is best to avoid lakes with algae blooms and pay attention to warning and closure signs. Only time will tell if this will be a big year for algae blooms. If you want to learn more, check out these resources:

Read the full article from the Department of Ecology here. 

Report a Bloom

If you see a bloom, it is best to report it to your local government so they can assist in identifying and testing the bloom. If you are part of a community association that cares for a lake or an active citizen, you can take a sample for testing yourself - if you decide to take your own sample be sure to follow the instructions from the Washington State Toxic Algae website, take the proper precautions, and notify your local government that you have submitted a sample. 

Government staff and lab testing for algae are only available during regular business hours. Testing usually takes up to two days for results to be returned. So once a bloom is spotted, if it impacts a swimming area it is likely to be closed as a precaution for at least a few days.

Below is a list of lakes in King, Pierce, and Snohomish Counties that tested above state guidelines in the past year for toxic algae and the month it occurred using the State's Toxic Algae program. You can find data on your lake here.


  • Cottage Lake - August
  • Echo Lake Beach - September
  • Hicklin Lake - July/August
  • Lake Jeane - September
  • Lake Marcel - July
  • Lake Wilderness Beach - September
  • West Green Lake Beach - October


  • Ohop Lake - September
  • Palmer Lake - August/October
  • Spanaway Lake - July/August/September/October
  • Tanwax Lake - October


  • Echo Lake - October

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