Pollution from British Columbia coal mining operations is making its way into Montana and Idaho’s Kootenai River. A U.S. Environmental Protection Agency study found high levels of selenium in mountain whitefish eggs and that could be impacting the species’ reproduction.
The results of the study examining mining’s downstream impact on the Kootenai River were released Monday.
“The selenium was mostly rather low in a variety of fish, but in a few fish, mostly in Mountain Whitefish, there were high selenium levels found in the eggs we collected,” EPA Hydrologist Jason Gildea explained.
It’s been known for some time that coal operations along British Columbia’s Elk River are elevating selenium concentrations in the transboundary Lake Koocanusa, but little study has been done downstream in the Kootenai River.
EPA’s study collected over 140 fish samples and tested water samples for selenium and other contaminant levels four times starting in the fall of 2018 and ending this spring. Concentrations of selenium in river never exceeded EPA recommendations for fish health during that time, and the levels found in whitefish eggs don’t pose a risk to human health.
However, the concentrations could impact the species’ reproduction.
“It’s really impacting the fish at the egg and fry stage rather than fish and the adult stage,” Gildea said.
Contaminated fish eggs sometimes fail to hatch and selenium has been known to cause deformities in fry after they feed on their yolk sack.
Unrelated to mining activity, Mercury levels in a number of fish sampled in the study were found to exceed EPA’s recommendation for human consumption, and Montana Fish, Wildlife and Parks will issue a consumption advisory for the area. FWP said levels are relatively low and are common statewide.
The agency said it will continue to work with state, tribal and Canadian partners to address selenium levels in Lake Koocanusa. Both FWP and EPA hope to fund more selenium research on the Kootenai River.