Freshwater Algae Control program

People and animals can become seriously ill, or even die, after exposure to toxic blue-green algae (cyanobacteria). Although most blooms are not toxic, toxicity is hard to predict. A single species of algae can have toxic and non-toxic strains, and a bloom that tests non-toxic one day can become toxic the next.

Blue-green algae blooms may turn the water pea soup green, brownish, or even red. When blue-green blooms start decomposing, they can turn bright blue or white and are often reported as paint spills.

Our Freshwater Algae Control program includes resources to:

  • Find your lake and see if it's been tested for harmful algae bloom.
  • Learn how to report an algae bloom.
  • Access grant funding to manage excessive harmful algae bloom growth.
  • Stay informed by signing up for our listserv.
  • Learn more about best management practices to prevent and treat algae blooms in lakes.

Toxic algae identification, monitoring, and reporting

Go to the Washington State Toxic Algae website to:

  • Find your lake — Use our database to locate a lake and find out the most recent testing.
  • Report a bloom — Local jurisdictions, lake managers, and Washington residents can report an algae bloom and sample it to test for potential toxins produced by algae.
  • Learn more — Find out about the health risks and how to identify toxic algae.


We provide small grants of up to $50,000 to state agencies, cities, counties, tribes, and special purpose districts to fund projects that prevent, remove, reduce, or manage excessive freshwater algae growth.

For more information about the requirements and eligibility, view our Freshwater Algae Program Grant guidelines and Freshwater Algae Program grants.

Stay informed

To receive toxicity reports about freshwater algae blooms, join our email list.

Find out more about lake water quality and look up a lake.

Best management practices for lakes

You can help keep your lake healthy by taking the following steps:

  • Maintain your septic system
  • Manage waterfowl
  • Use recommended landscape practices
  • Control runoff and soil erosion
  • Reduce or eliminate use of fertilizers
  • Properly dispose of pet wastes
  • Wash vehicles away from the lake
  • Reduce or eliminate the use of pesticides

For more information visit our clean water education website, Washington Waters - Ours to Protect.