Officials with the Humboldt County Department of Health and Human Services (DHHS) are warning recreational users of all fresh water bodies to avoid contact with algae this summer and early fall.


Blue-green algae, also known as cyanobacteria, are found naturally in water and wet environments, but prefer warm, stagnant, nutrient-rich water and are found most often in ponds, lakes, and slow moving rivers.

Photo: Algae in the South Fork Eel River, 7/17/14


A bloom is a build-up of algae that creates a green, blue-green, white, or brown coloring on the surface of the water, sometimes occurring as mats or scum.


Although blooms can occur at any time of year, they occur most often in the warmer months between June and September.


Some species of blue-green algae produce toxins, so skin contact and ingestion can be dangerous. Children and pets are at the greatest risk of serious toxic effects from blue-green algae.

How to Avoid Toxic Exposure:

  • Do not swim in water with scum layers or blooms.
  • Do not allow children or pets to swim in water with scum layers or blooms.
  • If you come into contact with a bloom, wash your skin and hair thoroughly. If wearing a swimsuit, pay careful attention to skin under the swimsuit.
  • If your pet comes into contact with a bloom, wash it thoroughly with clean water to prevent blue-green algae ingestion while your pet cleans itself.
  • Do not eat fish or shellfish caught or harvested in a bloom area.
  • Respect any water body closures by public health authorities.

If you think you or someone else is displaying symptoms of blue-green algae poisoning, call your physician or the California Poison Center Help Hotline at 1-800-222-1222.

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