Health - Wiser Lake Updates

Posted on: August 11, 2023

People, Pets Should Avoid Contact with Wiser Lake Water; Microcystin Biotoxin Found at High Levels

Recent sampling at Wiser Lake detected microcystin, a toxin produced by algae, at levels that may be harmful to people and pets if it is ingested. People and their pets should avoid water contact at Wiser Lake. 

WCHCS first posted caution signage at Wiser Lake in 2019 due to consistently elevated toxin levels. Recent test results continue to show an ongoing health risk. By US Environmental Protection Agency standards, current toxin levels are higher than the maximum safe level. 

How is Biotoxin Harmful? 

Microcystin can cause liver damage in people and pets. Ingesting lake water is the primary human and animal health concern. Boating or fishing at the lake has limited contact with the water and is considered low risk. However, activities in the water such as waterskiing, jet-skiing, and swimming pose a greater risk since someone is more likely to swallow water. Any activity that involves contact with the water should be avoided. Do not let pets swim in or drink from the lake near a visible bloom Pets often lick their fur after swimming and may ingest toxins while grooming. 

Research Study Continues

Microcystin and other algal toxins naturally occur in lakes. Nutrients in fertilizer, pet and wildlife waste, and agricultural runoff provide food for algal growth and can fuel freshwater algal blooms. Through a grant from the Washington State Department of Ecology, WCHCS is conducting a study of Wiser Lake to find the source of nutrient inputs that could be causing these harmful algae blooms. Monitoring will last through April 2024. The next phase of the project will be a data analysis, followed by development of recommendations to reduce harmful algae blooms in the lake.

You can learn more about the study at, and more about harmful algal blooms in general at or at

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