
WINCHESTER, ID — The Nez Perce Tribe’s Water Resources Division has issued a public health advisory for Winchester Lake following the detection of high levels of cyanobacteria, commonly referred to as blue-green algae. The harmful algal bloom presents risks to people, pets, and livestock.
Recent testing revealed the presence of cyanotoxins, toxic compounds released by cyanobacteria that can cause a range of health issues. While these bacteria occur naturally in Idaho’s lakes and reservoirs, warm temperatures can trigger blooms that result in dangerous concentrations of toxins.
Officials urge the public to take the following precautions:
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Avoid contact with the water, including swimming, wading, or playing near the shoreline.
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Prevent children and animals from drinking or entering the water.
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Do not drink or cook with lake water, even if boiled. Boiling does not remove the toxins and can intensify them.
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Wash hands thoroughly with clean water after handling fish or lake-related objects.
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If consuming fish from the lake, clean them with uncontaminated water and remove all skin, fat, and internal organs before cooking, as cyanotoxins can accumulate in fish tissue.

Symptoms of cyanotoxin exposure can vary depending on the type and level of contact. Individuals may experience skin rashes, eye irritation, respiratory issues, stomach pain, vomiting, or dizziness. Those with liver conditions may also notice jaundice or darkened urine. Anyone experiencing symptoms after contact with the water is advised to seek medical attention or call the Poison Control Center at 1-800-222-1222.
To report symptoms linked to algae exposure, residents can also email: algae@deq.idaho.gov.
Officials advise continued caution for anyone considering visiting Winchester Lake until further notice.