Montana alters selenium limits to protect lake from B.C. mining pollution

The U.S. state of Montana has passed stricter requirements on selenium levels in Lake Koocanusa and the Kootenai River in an attempt to guard against Canadian mining pollution and protect aquatic life and water quality.

Montana’s Department of Environmental Quality’s (DEQ) Water Quality Planning Bureau has been working with the British Columbia Ministry of the Environment for six years to address rising selenium levels in Lake Koocanusa, which extends north from the Libby Dam over the Canadian border into British Columbia.

Montana’s DEQ singled out the operation of B.C.’s Teck Resources, which mines and ships large reserves of high-grade coal globally for steel production, and is currently attempting to develop even more mines in the area. The company suggests it has made “significant progress” on the Elk Valley Water Quality Plan, building two water treatment facilities that are treating 17.5 million litres of water a day, with a goal of ramping up capacity to 47.5 million litres a day by 2021.

U.S. officials first noticed Lake Koocanusa’s rising selenium levels in 2005, 100 kilometres south of B.C.’s Elk Valley mines. The downstream pollution within Lake Koocanusa has already reached levels of 1.1 micrograms per litre, state officials said, but the contamination did not exceed the national standard of five micrograms per litre set in 1987.

Now, the new water column limit for the lake will be 0.8 micrograms per litre, and the Kootenai River will have a new threshold of 3.3 micrograms per litre.

High selenium levels adversely affect a broad range of aquatic life and become concentrated in the food chain, particularly in lakes, potentially compromising reproduction in certain fish. In 2018 and 2019, whitefish from the river contained selenium that exceeded national standards.

“While of metallurgical quality, the coal resides deep within mountainous terrain along the Elk River Valley, which means large quantities of overburden remain as part of the mining,” officials from Montatna’s DEQ said in a statement. “The selenium leaches out of this waste rock and into the Elk River, a tributary of the Kootenai River which forms Lake Koocanusa behind Libby Dam.”

In B.C., meanwhile, provincial officials released a fall statement indicating that they had not yet selected a proposed water-quality objective for selenium, but remain “committed to a science-based process informed by the best data available.” Officials said that they still need to consult with Ktunaxa Nation Council.

The new U.S. limits are based on research by selenium scientific experts and the Lake Koocanusa Monitoring and Research Working Group that included public meetings, data collection and a peer-reviewed modeling report.

The researchers also created new selenium standards for fish tissue. They are broken down into egg-ovary (15.1 mg/kg), muscle (11.3 mg/kg) and whole-body (8.5 mg/kg) selenium values for both water bodies.

Montana’s Board of Environmental Review adopted the new limits on December 11, following a request by the DEQ.

“The department is extremely pleased that after an extensive multi-year process that included public engagement and collaboration, the proposed selenium standards have been passed. The new standards will protect Montana and downstream waters,” said DEQ Director Shaun McGrath in a statement to media.