BLUE-GREEN ALGAE health concerns

Picture1Stockton, CA – Warm temperatures are here and when conditions are right, blue-green algae can rapidly build-up or bloom on the surface of reservoirs, rivers, creeks, lagoons, lakes and ponds. Environmental Health and Public Health officials are urging swimmers, boaters, and recreational users to avoid contact with blue-green algae (BGA), also known as cyanobacteria. The algae blooms may produce toxins that can present a health hazard to humans and animals. The algae blooms can look like green, blue-green, white, or brown foam and scum floating on the water. Children are especially vulnerable because they play on the shoreline, drink more water than adults when swimming, and are of a smaller body size. Dogs are especially vulnerable to BGA poisoning and many dogs are lost each year because they tend to drink more water and lick algae off their fur.

Human Exposure General Health Effects:

  • Rashes or other skin irritations.
  • Allergy-like reactions, runny nose or sore throat.
  • Toxins ingested in large amounts can cause sharp, severe stomach problems like diarrhea and vomiting, liver damage, numb limbs, tingling fingers and toes or dizziness.

Animal Exposure Health Effects:

  • Weakness, staggering
  • Difficulty breathing
  • Convulsions
  • Vomiting and diarrhea
  • Death if not treated

Statewide Guidance on Harmful Algae Blooms recommends the following:

  • Avoid wading and swimming in water containing visible blooms or water containing algae scum or mats, which are most often present at the shoreline.
  • Take care that pets and livestock do not drink the water or swim through scums, mats, nor lick their fur after going in the water. Wash exposed pets in clean drinking water.
  • If no algae scums or mats are visible, you should carefully watch young children and warn them not to swallow the water.
  • Do not drink, cook, or wash dishes with untreated water.
  • Consume fish only after removing guts and liver, and rinsing fillets in clean drinking water. Mussels should not be consumed.
  • Get medical treatment right away if you think you, your pet, or your livestock might have been poisoned by blue-green algae toxins.

Environmental Health Department staff will be posting Health Advisory signs at local marinas cautioning swimmers, boaters and recreational users to avoid contact with BGA.

For more information, visit:

San Joaquin County Environmental Health Department: or call (209) 468-3420

San Joaquin County Public Health Service: or call (209) 468-3411

California Cyanobacteria Harmful Algal Bloom (CCHAB) Network: council/cyanohab network/index.html

California Department of Public Health:

State Water Resources Control Board:

Office of Environmental Health Hazard Assessment:

U.S. Centers for Disease Control & Prevention:

U.S. Environmental Protection Agency:

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