07/10/2025 | Press release | Distributed by Public on 07/10/2025 09:47
The Department of Health and Welfare (DHW), in coordination with the Nez Perce Tribe Water Resources Division, is issuing a health advisory for Winchester Lake, urging caution when recreating in or near the water. Winchester Lake is near U.S. Highway 95, located at Winchester Lake State Park and approximately a half mile south of the city of Winchester.
DHW works closely with Idaho North Central Public Health, the Idaho Department of Environmental Quality (DEQ), and the Nez Perce Tribe to identify, respond to, and monitor cyanobacteria harmful algal blooms (cyanoHABs).
Recent samples taken by Nez Perce Tribe Water Resources Division from Winchester Lake showed high amounts of toxin-producing cyanobacteria. The toxins they produce (cyanotoxins) can be harmful to people, pets, and livestock.
When recreating near Winchester Lake, take the following precautions while the advisory is in effect:
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 don't all look the same. They may look like mats, foam, spilled paint, or surface scum, and have a foul odor.
Mats can be out of sight on the bottom of the water body. Pets, livestock, and wildlife can get sick or die, within minutes to days after cyanotoxin exposure.
Dogs may become sick first 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.
For more information about cyanoHABs:
The Idaho Department of Health and Welfare is dedicated to strengthening the health, safety, and independence of Idahoans. Learn more at healthandwelfare.idaho.gov.