Health advisory issued for Spring Valley Reservoir

Oct. 8—Idaho Public Health on Wednesday issued a health advisory urging people to not drink or swim in Spring Valley Reservoir near Troy because of harmful algal bloom in the water.

This is one of several local bodies of water that have been affected by toxin-producing algae in recent months. Sujata Connell, water quality manager with the Idaho Department of Environmental Quality, said this trend is largely caused by the weather.

She said 2021 has been a difficult year because prolonged high-temperatures and low precipitation often leads to harmful algae growing in waters.

"All those kinds of perfect storms have come together to really kick it up a notch," she said.

Moscow's Hordemann Pond, Elk Creek Reservoir in Clearwater County and Dworshak Reservoir in Clearwater County have all been affected by harmful algal bloom this year.

According to an Idaho Public Health news release, recent samples at Spring Valley Reservoir show concentrations of toxin-producing blue-green algae present that may cause illness to humans and animals.

The blooms may form thick mats along shorelines and can have an unpleasant odor.

The health district says people, pets and livestock should not drink or swim in the water at Spring Valley Reservoir. People who come in contact with the water should wash themselves with clean potable water as soon as possible. Areas of visible algae accumulation should be avoided.

Fish should be rinsed and cleaned with clean water. Only the fillet portion should be consumed.

People who are exposed to water with high concentrations of the algae may experience nausea, vomiting, diarrhea, difficulty breathing, skin irritation, allergic responses, liver damage or neurotoxic reactions such as tingling fingers and toes. Anyone with symptoms should seek medical attention. Boiling or filtering the water will not remove cyanotoxins

Connell summed up what people should do if they are unsure whether the lake, pond or reservoir they are visiting is safe.

"When in doubt, stay out," she said.

Connell said not much can be done to remove the harmful algae. It is usually a matter of waiting until the algae goes away as weather conditions change. She said it is still unclear how it affects the fish in the water.

She said state officials will continue to test the water for toxicity as well as cell counts of toxin-causing species. If those levels are low enough, Idaho Public Health will remove the advisory.

Kuipers can be reached at akuipers@dnews.com.