A health advisory was issued for the popular fishing destinations of Henrys Lake and Island Park Reservoir on Thursday after potentially harmful levels of algae were found.

The Eastern Idaho Public Health posted signs at entry points on both water bodies after Idaho Department of Environmental Quality took samples and found the presence of blue-green algae, a species that produces dangerous toxins.

“Based on some analytical results of algae samples there, we found it contains small levels of toxin that can be problematic for certain animals, certain people,” said Troy Saffle, regional administrator with DEQ. “We want to make sure the public is aware before they use either water body for recreation.”

Saffle said the health advisory was not uncommon for this time of year after the water warms up and the lake and reservoir levels drop.

“The old-timers tell us it’s happened always and forever,” Saffle said, of the late summer algae blooms.

Signs have been posted at popular put-in points warning visitors not to swallow or inhale water and to avoid direct contact with water containing visible algae.

“Drinking water from the lake is especially dangerous,” the health department notice said. “The toxins cannot be removed by boiling or filtering the water.”

James Brower, of Idaho Fish and Game, said it’s advisable to practice catch-and-release while fishing during the advisory.

“If they do choose to eat them, they should remove all fat, skin and organs before cooking since toxins are more likely to collect in those tissues,” Brower said.

“Ideally you would fillet the fish and eat only the fillets and not the skin,” Saffle said.

The health department cautioned that children and pets are particularly susceptible to the effect of blue-green algae.

“People exposed to blue-green algae might experience skin and eye irritation, nausea, diarrhea, numbness of hands and feet, and/or difficulty breathing,” the health department said. “If symptoms occur, call your doctor. For animals, symptoms might include muscle spasms, decreased movement, labored breathing, convulsion, and death. If pets are experiencing these symptoms, call your veterinarian immediately.”

Saffle said his department has been testing the two water bodies and arms of Palisades Reservoir regularly since 2016 and has not heard any definitive reports of sickness in people or pets. Other water bodies, get tested occasionally when someone reports a concern.

“Your (Labrador retrievers) that want to jump out of the car and jump into the water within 10 steps, those are the ones we worry about quite frankly,” Saffle said. “The algae tends to stack up in the margins. It’s often windblown, near a dock or a shallow part where you are typically going to put in a kick boat or play fetch with your animal.”

For questions about testing for blue-green algae, call the DEQ at 208-528-2650.

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