For Immediate Release: 8/30/2019

Potential Cyanobacteria and Harmful Algal Blooms in Auburn and Folsom Lake State Recreation Areas


Jorge Moreno   I    Information Officer   I   (916) 653-1986

AUBURN, CALIF. –California State Parks has recently become aware of suspected incidents of harmful algal blooms (HABs) within both the Auburn and Folsom Lake State Recreation Areas. As California confronts the realities of climate change, HABs have become increasingly common in rivers, lakes and reservoirs, and they can be especially dangerous to children and pets. State Parks is encouraging recreational users of all bodies of fresh water in Auburn and Folsom Lake State Recreation Areas to be aware of the potential for cyanobacteria harmful algal blooms (HABs).

In recent weeks, two separate incidents of possible cyanobacteria poisoning in dogs have been reported at Moony Ridge (Folsom State Recreation Area) and Oregon Bar (Auburn State Recreation Area). The incident at Oregon Bar resulted in the death of the dog, although the actual cause of death has not been confirmed. Sampling by Water Resources Control Board staff on August 23, confirmed the presence of cyanobacterial mats growing on rocks in a side channel of the American River at Oregon Bar. Caution signs have been posted in these areas and additional signage has been posted throughout the parks to increase public awareness of the potential risks. Algal blooms can form and die off fairly rapidly and it is difficult to continuously test and monitor the many lakes and miles of our local rivers. 

Most aquatic ecosystems in California contain harmless green algae, and many cyanobacteria do not affect animals or people. Nevertheless, it is important to stay safe and avoid contact with cyanobacteria, because some cyanobacteria species are capable of producing toxins that can be harmful to animals and humans. Dogs and children are most likely to be affected because of their smaller body size and tendency to inadvertently ingest the water or algal material.

People exposed to toxins may experience irritation of the skin, eyes, nose, throat or respiratory system. Symptoms of animal illness include: vomiting and/or diarrhea, lethargy, abnormal liver function test results, difficulty breathing, foaming at the mouth, muscle twitching and sometimes death. More information about health impacts for domestic animals and livestock can be found on the HABs Portal Domestic Animals webpage. 

Cyanobacteria can be present in fresh, estuarine or marine waters. HABs can be a variety of colors such as green, white, red or brown and may look like thick paint floating on the water. Not all HABs will appear on the water’s surface. Some form mats at the bottom of a waterbody (such as in wadeable rivers, as seen at Oregon Bar), and others float at various depths. More information on how blooms look can be found in our visual guide.

To report a bloom, do one of the following:

The California Water Resources Control Board recommends that people practice healthy water habits while enjoying the outdoors this summer at your local lake, river or stream:

  • Heed instructions on posted advisories if present.
  • Avoid algae and scum in the water and on the shore.
  • Keep an eye on children and pets (dogs).
  • If you think a HAB is present, do not let pets and other animals go into or drink the water, or eat scum/algal accumulations on the shore.
  • Don’t drink the water or use it for cooking.
  • Wash yourself, your family and your pets with clean water after water play.
  • If you catch fish, throw away guts and clean fillets with tap water or bottled water before cooking.
  • Avoid eating shellfish if you think a HAB is present.
  • Get medical attention immediately if you think that you, your children, your pet or livestock might have been poisoned by cyanobacteria algae toxins. Be sure to tell the doctor or veterinarian about possible contact with cyanobacteria algae.

For more information about HABs, please visit:

California Harmful Algal Blooms Portal

California Cyanobacteria and Harmful Algal Bloom (CCHAB) Network:

California Department of Public Health Resource Page



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California State Parks provides for the health, inspiration and education of the people of California by helping to preserve the state’s extraordinary biological diversity, protecting its most valued natural and cultural resources, and creating opportunities for high quality outdoor recreation.