Harmful algal bloom at Ice Harbor Dam
By Terry Murry on Sunday, October 5th, 2025 in Columbia Basin News More Top Stories
WALLA WALLA – (News release from WWCDCH) The Walla Walla County Department of Community Health has issued a warning for Ice Harbor Dam due to elevated levels of cyanobacteria (microcystin), also known as toxic/blue-green algae. Results from water samples taken on Monday, September 29, 2025, measured 80.9 ug/L microcystin, exceeding state recreation guidelines.
Microcystin is a liver toxin that can pose a significant health risk if toxins are ingested, inhaled, or upon skin contact. Exposure to these toxins can cause serious illness in humans, particularly children, and death for pets that are exposed. While the warning advisory is in place, officials recommend taking the following precautions:
• Do not swim or water ski.
• Do not drink the water.
• Keep pets and livestock away from the water.
• Clean fish well and discard guts.
• Avoid areas of scum when boating.
• When in doubt, stay out.
Avoid water that is discolored, smells bad, or has foam, scum, or mats. Dead animals on or near the shoreline can also indicate the presence of toxic algae. Whenever you are at a lake or river, and see a yellow “WARNING” sign, this means there is toxic algae in the lake, and the water is unsafe for people and pets.
If you see a red “DANGER” sign, there are very high concentrations in the water and that the body of water is closed. You should not swim, wade, fish, or boat in areas where red “DANGER” signs are posted.
If you believe you or your pet may have been exposed to water containing an algal bloom, rinse off with fresh water immediately. If you, a person, or pet, experience weakness/incoordination, vomiting, diarrhea, rash, or headache after contact with potentially affected water, seek medical or veterinary attention immediately.
Officials will continue to monitor the area and will take routine water samples to test toxin levels. Information and signs will be updated as conditions change.
