Friday September 2, 2022
Alaska Native News —
A major concern about mine development in Alaska’s Bristol Bay region and in many watersheds throughout Alaska is the potential for toxic waste to contaminate water and threaten world class salmon runs. Copper is a particular concern because it is acutely toxic to fish at relatively low concentrations.
The U.S. Environmental Protection Agency (EPA) uses a model to predict copper toxicity to aquatic organisms. The model results are used to establish water quality guidelines. How well this model works under water chemistry conditions in Alaskan watersheds is poorly understood, however, and risk assessments using this model could be underestimating toxic levels of copper.
Seeking to resolve this uncertainty, researchers at the University of Alaska Fairbanks completed a study to determine the acute lethality of copper to sockeye, coho and Chinook salmon. They conducted these studies with salmon at the swim-up fry life stage, a time when salmon can be the most vulnerable to toxins in the water. In comparing their findings to those predicted by the U.S. EPA model, the research team confirmed that under the water conditions found in the Bristol Bay region, the toxicity predictions of the EPA model are underestimated.