The concentrations of selenium and nitrate entering the Elk River and Northwest Montana’s Kootenai watershed as a result of coal-mining operations in British Columbia are likely without measured precedent, according to a new study authored by U.S. Geological Survey scientists.
The mining-related growth of selenium, nitrate and sulfate concentrations in the Elk River, “are among the largest documented increases in the primary literature,” the researchers write.
Lead study author and USGS researcher Meryl Storb said her team perused all of the studies they could find on mining and solutes published in the past 40 years but couldn’t find anything “even close” to matching the trendlines in British Columbia’s Elk River, where selenium concentrations have grown sixfold and nitrate concentrations have grown by nearly 800% since 1979, reports the Montana Free Press.
“The percent increase in the concentration of nitrate and selenium are some of the largest we know exist based off peer-reviewed scientific publications,” Storb said, adding that they reviewed studies conducted on mines in Appalachia, southern Idaho and China.
Selenium has been a source of particular concern in the Elk and Kootenai (Kootenay in Canada) watersheds because it can cause reproductive failure in fish and lead to spinal, gill and facial deformities. The element is an essential nutrient in small quantities but is toxic to egg-laying species including fish and waterfowl in excess.
The study, published in the scientific journal Environmental Science & Technology on Nov. 3, found that both Canada’s selenium water quality standard of 2.0 micrograms per liter and Montana’s more stringent site-specific standard of 0.8 micrograms per liter are “regularly exceeded on both sides of the border.” Selenium concentrations in the U.S. portion of Lake Koocanusa have not met the 0.8 micrograms standard for that waterbody since July 2020.
The study compared two tributaries of Lake Koocanusa, a 90-mile reservoir that spans the U.S.-Canada border, to help ecologists and water managers determine how much of the increase in selenium and nitrate can be attributed to coal mining as compared to the region’s natural geology.
One of Koocanusa’s tributaries, the Elk River, is profoundly impacted by mountaintop removal coal mining north of Fernie, British Columbia. The other, the Kootenay River, is not. Since Elk River Valley mining took off in the 1970s, selenium concentrations in the Elk River have grown dramatically and are continuing to rise despite the fact that the mines make up just 3% of the Elk River basin’s total drainage area.
In addition to releasing selenium in the Elk-Kootenai watershed, the ammonium nitrate used in mining explosives is responsible for adding hundreds of tons of nitrate to downstream waterways every year, Storb said. The overall concentration of nitrate in the Elk River has increased nearly ninefold over the past 43 years, the study found. Rising nitrate levels can throw aquatic food webs off-kilter, contributing to algal blooms, which can threaten some aquatic insects and fish that feed on them.
Teck Resources, which is headquartered in Vancouver, British Columbia, operates the four largest coal mines located in the Elk River Valley. The mines collectively produced nearly 25 million tons of steelmaking coal in 2021 and were responsible for nearly half of British Columbia’s 2020 mining revenues. The company has commissioned economic research showing it sustains some 30,000 jobs.
Teck is investing more than $1.4 billion in water treatment technology to remove selenium from surface waters before it flows downstream. Despite adding new treatment technology and substantially increasing the volume of water it treats, selenium concentrations in the Elk River and Lake Koocanusa continue to rise. Teck treats water using both active, tank-based treatment facilities and a saturated rock fill technology that’s designed to reduce the chemical weathering process that releases selenium into watersheds from waste rock after rain and snowfall.
Storb said the expansion of mining operations and treatment capacity limits are likely contributing to that dynamic. During periods of high runoff, Teck’s facilities are maxed out and unable to treat all of the surface waters picking up selenium and carrying it into Montana and Idaho.
Some of the selenium entering the watershed could also be percolating through groundwater, where it can later rejoin surface waters, Storb said, adding that she’d like to see further research into those interactions. Teck currently only treats surface water and has no plans to expand treatment to groundwater.
“With limited knowledge surrounding surface water-groundwater interaction and potential groundwater contamination, it is unclear if treatment of surface water alone will sufficiently reduce the mass of solutes moving downgradient in the watershed and into [Lake Koocanusa] to meet U.S. water-quality regulations,” the study reads.
Storb said she’s also interested in learning more about selenium and nitrate distribution dynamics in Lake Koocanusa, which “kind of behaves like a river but also kind of behaves like a lake.”
“A better understanding of when and where contaminants are distributed has very important connotations for how it could be regulated and managed,” she said.
The Ktunaxa Nation Council advocates for six bands of Indigenous people spread across present-day British Columbia, Montana and Idaho. The council has for more than a decade asked the federal governments of the United States and Canada to refer the pollution issue to the International Joint Commission, which was created by the Boundary Waters Treaty of 1909 to adjudicate issues that arise in their shared waterways.
If the IJC conducts an investigation into mining pollution, all parties will have a common set of information upon which they can base regulatory decisions. The IJC could also recommend, though not enforce the implementation of, solutions to mitigate pollution.
In March, President Joe Biden and Canada Prime Minister Justin Trudeau pledged to reach an agreement “in principle” by the end of the summer to address the pollution issue, but that agreement failed to materialize. U.S. Sen. Jon Tester, D-Montana, has urged U.S. Secretary of State Anthony Blinken to press forward with a unilateral IJC referral — something that’s happened just once in the commission’s 114-year history — if Canada refuses to come to the table.
“Our clean water is too important to sit idly by while Canada fails to uphold its end of the agreement,” Tester wrote, citing concerns related to aquatic ecosystems and Montana’s outdoor recreation economy. He added that he’s also concerned the U.S. could fail to meet its treaty and trust obligations to tribes dependent on the watershed, including the Confederated Salish and Kootenai Tribes of Montana.
Gianforte argued that a referral would be “premature due to the ongoing efforts of Montana to collaboratively develop and implement selenium standards for Lake Koocanusa and the Kootenai watershed.” Gianforte also wrote that British Columbia’s provincial government was opposed to a referral, a position that has since shifted.