Idaho Recreational Waters

The Idaho Division of Public Health and Idaho’s local public health districts work together to investigate outbreaks of illness associated with drinking or recreational water as well as provide information about well water safety and Harmful Algal Blooms in the area.  

Cyanobacterial Harmful Algal Blooms - cyanoHABs

CyanoHABs are made of cyanobacteria that can produce toxins which can harm humans and animals. CyanoHABs can occur in water bodies in Idaho when water temperatures and nutrients increase, and cyanobacteria rapidly increase in number producing a bloom. Blooms can be blue, bright green, brown, or red and may look like paint, foam, scum, or mats on the surface of freshwater lakes and ponds.

People and animals can be exposed to cyanoHAB toxins by swallowing or touching the water during recreational activities, such as fishing, swimming, water skiing, or when eating fish from a bloom. Exposure to cyanoHABs may cause skin and eye irritation, nausea, vomiting, and sometimes death. Keep your family and pets safe by avoiding water with a bloom.

Mucky, green water at Henrys Lake caused by cyanobacterial bloom
Idaho Recreational Water Health Advisories
Recreational water

The Idaho Division of Public Health works with Idaho’s local public health districts to investigate outbreaks of illness associated with drinking or recreational water. 

Recreational waterborne illnesses result from swallowing, breathing, or having contact with recreational water. Recreational water is any water which is used by a significant number of persons for recreation or play such as in natural or artificial bodies of water and man-made facilities.

Recreational water use is associated with significant benefits to health and well-being. Yet the Centers for Disease Control and Prevention has noted a steady increase in the number of reported outbreaks of diarrheal illness associated with recreational waters. These reports suggest that spread of illness through aquatic venues occurs routinely during the swimming season.


Animal Exposure


Is it safe for my dog to go in the water when there is a cyanobacterial harmful algal bloom?

No. Dogs are more likely to be exposed to cyanotoxins from drinking contaminated water, swallowing water while swimming and retrieving a ball or stick, and from licking cyanobacteria from their fur. Some animals will be exposed by eating mats of cyanobacteria or dead animals, such as fish, found near the bloom or by retrieving waterfowl that might have cyanobacteria on their feathers after swimming through a bloom. Carry clean, potable water for your dogs to drink when recreating around a body of water with a cyanobacterial bloom and keep them on-leash if they can’t resist eating tempting items.

What should I do if my dog goes into the water where there is a bloom?

Immediately wash the dog off with clean water. Call your veterinarian, or the ASPCA Animal Poison Control Center at 1-888-426-4435 or the Pet Poison Helpline at 1-855-764-7661 (note there is a fee for these calls). Dogs can become sick within minutes to hours after exposure. Signs of cyanotoxin poisoning depend on the types of toxin and how the dog was exposed. Do not call Idaho Department of Environmental Quality or Idaho public health officials for diagnosis of your dog’s illness or advice on caring for your dog – you will be referred to your veterinarian or the above call lines.

My dog got sick or died after swimming in a lake or river. Will Idaho public health agencies, Idaho Department of Environmental Quality, or the agency managing a lake pay for testing my dog?

No. Testing of pets is the responsibility of the owner. There are no commercially available tests for detection of cyanotoxin in dogs. Idaho public health agencies test water when there is a suspected harmful cyanobacterial bloom. Report suspected cyanotoxin poisoning to the Idaho Department of Environmental Quality through the DEQ Report a potential bloom link.


CDC Cyanobacterial Harmful Algal Bloom Associated Illness
Alerta para la seguridad de los animales
Animal Safety Alert Fact Sheet
Recreational water resources