Blue-Green Algae (Cyanobacteria)

Algae, including blue-green algae (aka cyanobacteria), can be normally found in many water environments, such as the Russian River. When high temperatures and increased nutrient levels in the water occur, algae can grow more rapidly than normal. This creates blooms of algae that may cluster together to look like a mat floating on the surface of the water. Most algae is harmless; however, some species of BGA, classified as harmful algal blooms (HABs), produce toxins that can harm the health of humans and animals.

Throughout the summer of 2020, the Environmental Health & Safety Section (EHS) of the Sonoma County Department of Health Services (DHS) and the North Coast Regional Water Quality Control Board (NCRWQCB) will continue the Pilot Program of monitoring conditions along the Russian River.

Currently, there are no health advisories in place and the Russian River is open to visitors. Should conditions change to support the growth of blue-green algae (cyanobacteria) and HABs, information will be posted on the County webpage along with any health precautions recommended by DHS. Information will be updated regularly.

Healthy Water Habits

At all times, DHS encourages individuals to follow healthy water habits for recreational river use:

  • Do not drink river water. Do not cook or wash dishes with river water
  • Wash yourself and your family with clean water after river play
  • Consume fish only after removing guts and liver, and rinsing fillets in clean water. Mercury has been detected in fish from the Russian River. Check here for additional guidance regarding mercury in fish: https://oehha.ca.gov/advisories/russian-river
  • Bring your life jacket, but leave the alcohol at home. The side effects of alcohol – impaired judgment, reduced balance, poor coordination – can be magnified by the boating environment. For additional safety tips please visit the State Parks Division of Boating and Waterways: http://dbw.parks.ca.gov/?page_id=28711.

Test Results from Previous Years

State Trigger Levels

Caution Any detected1 μg/L0.8 μg/L
Warning 20 μg/L4 μg/L6 μg/L
Danger 90 μg/L17 μg/L20 μg/L

Source: State Water Resources Control Board

All levels are in micrograms per liter (μg/L).

Related Links

Resources for Mitigating Harmful Algal Blooms (HABs)
Source:California Water Quality Monitoring Council

Are Harmful Algal Blooms Affecting Our Waters?
Source: State Water Resources Control Board

Algal Blooms
Source: California Department of Public Health.

California Cyanobacteria and Harmful Algal Bloom (CCHAB) Network
Source: California Water Quality Monitoring Council

Harmful Algal Bloom (HAB)-Associated Illness
Source: Centers for Disease Control and Prevention

Contact Information

Public Health Division
County of Sonoma
Business Hours
Monday – Friday
8:00 AM – 4:00 PM
Office Location
625 5th Street
Santa Rosa, CA 95404
38.441823, -122.7137698

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