Unsafe toxin detected in algae blooms on Rufus Woods Lake

Published June 21, 2019

SEATTLE – An unsafe level of a naturally occurring toxin was detected in algae blooms at Rufus Woods Lake, prompting U.S. Army Corps of Engineers’ officials to post Washington State Department of Health warnings against swimming, water skiing and other in-water activities at the lake near Bridgeport, Washington.

The toxin of concern is anatoxin-a, a nerve toxin produced by some blue-green algae blooms found in water bodies throughout the state.  Blue-green algae blooms often rise to the water’s surface forming a thin oily-looking surface scum.  The toxin can be lethal to animals if ingested at high enough concentrations.

While it’s safe to eat properly cleaned and gutted fish, water should not be consumed and steps should be taken to keep livestock and pets away from the water.  Boaters are advised to avoid areas where floating algae blooms are present.

Samples of floating algae blooms were taken and forwarded to King County Environmental Laboratories for testing and analysis.  Test results indicate that concentrations of anatoxin-a in the floating algae were as high as 311 micrograms per liter.

The Washington Department of Health recommended guideline for anatoxin-a concentrations are one microgram per liter for recreational uses of the water.  Samples will continue to be taken and analyzed until anatoxin-a levels are determined to be below state recreational guidance values.

Access to Rufus Woods Lake remains open to the public.

For more information about toxic blooms, visit the Washington State Toxic Algae website at https://www.nwtoxicalgae.org/Default.aspx.

Release no. 19-025