WINCHESTER, ID – The health advisory for Winchester Lake remains in effect as harmful algal blooms (HABs) continue to pose a risk to public health.
The Idaho Department of Health and Welfare (DHW), in partnership with the Nez Perce Tribe Water Resources Division, urge the public to avoid contact with the water. The harmful blooms contain toxins that can be harmful to people, pets, and livestock.
The advisory initially issued on July 10, 2025, remains active due to ongoing detection of toxin-producing cyanobacteria in the water. The toxins they produce, known as cyanotoxins, can cause a range of symptoms in those who come into contact with or ingest contaminated water. Health risks may include skin rashes, stomach pain, diarrhea, and more serious effects like liver damage.
DHW advises the public to:
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Stay out of the water, including swimming, wading, or any other activities that involve contact with the lake.
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Keep pets and livestock away from the water, and wash any exposed skin or fur with clean water immediately.
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Do not drink or cook with water from the lake. Boiling or filtering the water does not remove the toxins.
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Wash hands thoroughly after handling fish or any objects from the water, and take care when consuming fish caught from the lake.
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Watch for any signs of illness and seek medical attention if necessary.
For further information on the lake’s condition or updates on the advisory, individuals can contact Winchester Lake State Park at 208-924-7563.