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McNary Refuge Again Safe for Recreation by Sheila Hagar Walla Walla Union Bulletin, November 1, 2022

Walla Walla County health officials have continued to monitor the cyanobacteria, otherwise known as blue-green algae, situation at McNary National Wildlife Refuge and on Monday declared the water safe for recreational use.

Testing in August showed a high concentration of the bacteria and weekly testing ensued.

"Blue-green algae can appear throughout the year in many Washington lakes and rivers, but it most often develops in summer and early fall when there's a wealth of warm, calm water and sunlight. While many blue-green blooms are nontoxic, some produce nerve or liver toxins," according to Washington state's Department of Health.

"As cyanobacteria cells die, toxins are released into surrounding waters. Some toxins, called microcystins, are very stable and can remain in the water for several days after the bloom has disappeared. Microcystin is found most often in the scum floating on top of the water."

That scum can be harmful to people, pets and livestock.

October's sample test is the final one for the season, officials said.