Health advisory issued for HELLS CANYON RESERVOIR


Health advisory issued for HELLS CANYON RESERVOIR

Based on Idaho’s Department of Environmental Quality’s (DEQ) testing and Idaho’s public health advisory guidelines, Southwest District Health (SWDH) is issuing a health advisory for Hells Canyon Reservoir. SWDH urges residents to use caution when recreating in or near the water. Recent samples taken from “Big Bar” at the Hells Canyon water body indicate high concentrations of toxin-producing cyanobacteria, which can be harmful to people, pets, and livestock. Those with liver or kidney damage are at an increased risk of illness.

When recreating near or in Hells Canyon Reservoir, take the following precautions while the advisory is in effect:

  • Avoid swimming, wading, or other activities in the water. Take extra precautions to ensure children, pets, and livestock are not exposed to the water. Do not drink or cook with water containing a bloom. Boiling and filtering the water does not remove the toxins and can increase the risk of adverse health effects.
  • Wash hands thoroughly in clean water after handling fish caught in water experiencing a bloom. Cyanotoxins can accumulate in fish and the risk to people is being researched. Clean and wash fish thoroughly in uncontaminated water and dispose of internal organs before consumption. If you choose to eat fish from this area, filet the fish and remove all fat, skin, and organs before cooking.
  • Clean skin or pet fur with clean water as soon as possible after any water contact.

No updates will be provided until DEQ testing reveals toxins are below the health standard. The public will be advised when it is likely the concern no longer exists.

Symptoms of cyanotoxin exposure include rashes, hives, diarrhea, vomiting, coughing, and/or wheezing. More severe symptoms affecting the liver and nervous system may result from ingesting water. If symptoms persist, consult your healthcare provider.

Pets, livestock, and wildlife can get sick, or even die, within minutes to days after cyanotoxin exposure. Dogs are often the first affected because they are more likely to swim in or drink contaminated water or lick contaminated water or bloom material off their fur. If your pets or livestock have been in the water, immediately wash them with clean water to keep them from licking cyanobacteria off their bodies. Seek veterinary care immediately if your pets or livestock seem sick after going in or drinking the water.

Cyanobacteria are a natural part of Idaho’s water bodies. When temperatures rise, their populations can bloom and toxic chemical compounds, or cyanotoxins, can be released into the water. Blooms can vary in appearance, and may look like mats, foam, spilled paint, or surface scum, and have a foul odor. SWDH works closely with the Idaho Department of Health and Welfare (DHW) and the DEQ in identifying, responding to, and monitoring cyanobacteria harmful algal blooms (HABS).

For more information about harmful algal blooms, visit DEQ’s website at or DHW’s website at

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Media Contacts:

DEQ media contact:
Anna Marron

DHW media contact:
Greg Stahl

SWDH media contacts:
Ashley Anderson

Katrina Williams