Study Finds Dioxin Levels In Fish Down

A new study of Lake Roosevelt fish suggests that dioxin levels may be decreasing in the reservoir behind Grand Coulee Dam, a federal environmental official said Wednesday.

Janice Hastings, associate director of the Environmental Protection Agency’s water division in Seattle, wrote that the data is preliminary and formal conclusions should not be drawn until more comprehensive analysis is done.

The state Department of Health in 1991 advised fishermen to avoid eating too much whitefish caught in Lake Roosevelt because of dioxin concentrations. Scientists have not decided how much dioxin humans can consume without risking birth defects and other illnesses.

Hastings’ memorandum was sent to the Technical Advisory Committee of the Lake Roosevelt Water Quality Council meeting here Wednesday.

A final report is expected by late summer.

“Based simply on observation of the ranges of concentrations found, the major contributor to dioxin toxicity in previous samples … appears to have decreased in concentration in lake whitefish and in other species,” Hastings wrote. “This finding would be consistent with the trend of decreasing concentration reported by the Washington Department of Ecology from 1993 sampling.”

The EPA paid for a study of dioxins found in the flesh of Lake Roosevelt fish caught in July and August 1994, mainly by volunteers from the Spokane Walleye Club and other sports fishing clubs.

The study looked for the presence of chlorinated dioxin and furan compounds, or dioxins, which are suspected carcinogens.

Dioxins are byproducts of chlorine bleaching in pulp-paper production. Canadian pulp mills on the Columbia River are believed to be major contributors to Lake Roosevelt levels.

State environmental officials have said Canadian industries in recent years have significantly reduced the amount of effluents discharged into the Columbia.