Toxic algae blooms detected in Rufus Woods

Elevated levels of neurotoxin were detected in the middle section of Rufus Woods, according to a monitoring website that tracks toxic algae blooms.

A sample pulled June 25 from the "Mid Lake" region of the reservoir showed 13.760 micrograms of anatoxin-a per liter of water–well over the state Department of Health's guidelines for anatoxin-a in "recreational water bodies," which is 1 microgram per liter of water.

Anatoxin-a is a naturally-occurring substance produced by cyanobacteria, sometimes called blue-green algae - although it can appear brown, pea soup green, or blue green. In high levels, the toxin can cause real problems for humans and animals, including vomiting and diarrhea, numbness, muscle twitching and loss of coordination, and respiratory paralysis (loss of the ability to breathe.)

The "Mid Lake" sample site is about 24 miles downstream of the Grand Coulee Dam, approximately halfway between Grand Coulee and Chief Joseph dams, according to a public affairs specialist with the U.S. Army Corps of Engineers, the agency which collects samples on Rufus Woods.

The state Department of Ecology urges caution if you see an algal bloom, and to "give it room" and not drink, swim, play, or boat in areas with visible blooms. Pets should also be kept out of the water, which can have the appearance of slimy scum, clumpy clouds, or spilled paint on the water surface.

It is not the first time toxic algal blooms have resulted in elevated neurotoxins in the reservoir between Grand Coulee Dam and Chief Joseph Dam.

The website Washington State Toxic Algae shows elevated anatoxin-a has occurred every summer at various monitoring sites at Rufus Woods Lake, going back to 2011, which is the oldest data on the website for the lake.

Anatoxin-a can accumulate in the internal organs and tissues of fish that come in contact with cyanobacteria. "Human exposure to cyanotoxins may occur if fish are consumed from reservoirs with existing blooms of toxin-producing cyanobacteria," according to a study cited by the U.S. Environmental Protection Agency. However, the EPA notes, "No cases of toxicity in humans following ingestion of fish or shellfish exposed to cyanotoxins have been documented."

Pacific Aquaculture, which owns and operates triploid trout net pens in a stretch of the reservoir west of Nespelem, had not received notification of the elevated toxins.

"We haven't seen any adverse effects on the fish, but we just notify our team members to avoid any algae that breaks loose," said General Manager Bill Clark. He said water flow is usually fast enough to keep algae blooms to a minimum in Rufus Woods, though he noted this year's lighter snowpack in the mountains upstream means reduced flow volume this summer. 

The Army Corps of Engineers will continue to analyze samples until anatoxin-a levels are determined to be below state recreational guidance values.