Residents, boaters warned of toxic algae in Russian River

Toxic algal mats. (Photo:

The State Water Resources Control Board is cautioning boaters and other recreational water users after detecting toxic algal mats growing at the bottom of the Russian River.

Toxic algal mats are dangerous algae growths that detach from the riverbed and float at the water's surface or get stuck on the banks. The State Water Board and Sonoma County Department of Health Services previously announced in late July that they had detected blue-green algae toxins in the Russian River. The algae can be fatal to dogs and harmful to humans, especially children.

Residents are cautioned to avoid drinking or cooking with the water and to avoid touching any algal mats. Also, dogs and other animals should stay out of the water. 

Photos of toxic algal mats are available at: and the State Water Board has posted warning signs at recreational areas along the river.  

Underwater photograph of algal mats growing on a submerged log in the Eel River, CA. (photo:

Toxic algal mats may also infect wildlife living in the water, so the State Water Board has advised residents to throw away all fish guts, clean fillets with tap or bottled water and to avoid shellfish altogether.  

The Centers for Disease Control and Prevention warn that blue-green algae can cause a variety of symptoms, depending on the type of exposure. Individuals who ingest the algae or contaminated water may experience sore throat, headache, muscle weakness or even pneumonia, while coming into skin contact with the dangerous bacteria can cause swelling or blisters. 

According to the American Kennel Club, dogs exposed to blue-green algae may suffer from seizures, difficulty breathing, diarrhea and vomiting. 

Residents who think they or an animal may have been exposed should seek immediate medical treatment and contact the Public Health Division of the Sonoma County Department of Health Services. 

Algal blooms can be reported by emailing, calling the Harmful Algal Blooms hotline at 1-844-729-6466, calling Sonoma County Environmental Health at (707) 565-6565 or filling out a Bloom Report at