View of Lake Koocanosa from Moriah's Ledge in the summer. (JP Edge/Hungry Horse News)

If recent data from peamouth chub and other fish hold valid insight — and at least, biologists in Montana believe they do — selenium levels at Lake Koocanusa reach as high as 250% of what’s allowed in Montana waters.

Moreover, nearly half of the lake chub sampled for the data in 2020 from Montana Fish, Wildlife and Parks tested too hot for the trace mineral, often far exceeding the new statewide threshold for selenium in dried fish egg and ovary tissue.

Such tissue sampling serves as a key federal criterion in assessing selenium toxicity.

FWP now awaits additional results from comparatively limited specimens collected in 2021 but plans to join the U.S. Geological Survey this year for another round of robust sampling to further gauge selenium contamination in the popular Northwest Montana reservoir and water supply.

Excess selenium, described as an unseen killer of aquatic life, remains rooted in Canadian coal.

And “we had exceedances in some of the highest concentrations that we’ve seen, in several species,” Trevor Selch, a Helena-based FWP fisheries pollution control biologist, said while discussing the 2020 fish data.

The most recent egg-ovary data yet available, Selch said, Lake Koocanusa sampling in 2020 occurred as state officials worked to approve a suite of new selenium limits in Montana.

Ultimately passed December 2020, the new limits included the oft-challenged site-specific threshold of 0.8 microgram per liter of Lake Koocanusa.

The limit is more stringent than the U.S. Environmental Protection Agency’s recommendation of 1.5 micrograms of selenium per liter for lakes and reservoirs, drawing international and local ire.

British Columbia-based Teck Resources Ltd. has challenged the legality of the stricter 0.8 microgram limit for the reservoir — noting among other complaints that the site-specific standard remains “the most stringent in America.”

“We believe that review of the lake’s water quality and fish tissue data will reveal no escalating issues with selenium,” Teck officials wrote in a February briefing to a committee of legislators.

The briefing also noted “that careful expert review of the modeling done … will reveal that the model was used inaccurately and in a manner that overpredicts selenium concentrations in fish.”

Charging the measure is politically motivated, the Lincoln County Commission also levied several complaints in a recent editorial against the state maintaining a lower threshold than prescribed by the EPA, which approved the stricter standard in early 2021.

Overall, a special legislative committee is expected before April 1 to conclude all aspects of a “cooperative” review of how Montana established its Lake Koocanusa selenium limit.

Committee findings and any resulting recommendations are expected for review during the state’s 68th regular legislative session next year.

Findings will also be sent to the British Columbia Ministry of the Environment.

Fish egg and ovary tissue from the reservoir, meanwhile, is being tested against a separate statewide selenium threshold.

When measured, according to the EPA, egg-ovary selenium concentrations supersede the four other chronic selenium criteria, including that of lakes and reservoirs.

Protecting aquatic life remains the genesis of Montana’s new selenium thresholds.

Egg-ovary tissue sampling at Lake Koocanusa has included peamouth chub, redside shiner, longnose sucker, Northern pikeminnow and westslope cutthroat trout.

A common trace mineral, selenium bioaccumulates in fish in a way similar to that of mercury levels in tuna. And some fish species are more sensitive to selenium than others, said University of Montana researcher Erin Sexton.

Sexton, a senior research scientist at the university’s Flathead Lake Biological Station, said the mineral proves toxic in low concentrations to waterfowl, fish and invertebrates such as flies — known as an “invisible contaminant” causing unseen deformities and reproductive failures.

“The end point for selenium toxicity is an egg that fails to thrive,” Sexton said during a recent weekend presentation in Libby. “So you’re not going to see the thing that is impacted by selenium because it didn’t make it to life.

“You’re not going to see widespread deformities because most of those species did not make it into a viable fish or bird,” she said.

2020 egg-ovary sampling at Lake Koocanusa showed three fish species exceeding the new statewide threshold of 15.1 milligrams per kilogram of dried tissue.

Those were the peamouth chub, westslope cutthroat trout and the Northern pikeminnow.

Of 24 total samples, 11 peamouth chub specimen exceeded the current threshold — including one that contained 38.8 mg of selenium, a threshold overage of more than 250%, according to the FWP-provided data.

Similar results were found among westslope cutthroat trout, albeit with fewer total specimen. Six fish were sampled; half of them exceeded the egg-ovary threshold.

Lastly, one Northern pikeminnow specimen in 30 total samples exceeded the threshold with 21.4 mg of selenium detected, according to the data.

With some year-to-year data gaps and limited initial sampling, collaborative egg-ovary data since 2008 show lake fish consistently fell below the current tissue threshold until 2020, one of the most robust years of testing at the reservoir.

“2018, 2019 and 2020 are the years that we did pretty intensive sampling of all the species in the reservoir,” FWP fisheries biologist Selch said of the effort occuring in the spring and fall to capture a complex mix of varied fish spawns.

As FWP readies for additional testing, he said, the department awaits a final decision by Montana’s Department of Environmental Quality on what formally constitutes a breached selenium limit in the state.

The high levels shown in Koocanusa fish are born overwhelmingly of Canadian coal mining that leach into the reservoir via the Elk River.

Citing a lack of local selenium-bearing geology and otherwise low natural outflows of selenium regionally, Montana officials point to a growing several billion cubic-meters of Teck waste rock from surface coal mining in the Elk Valley.

Canada’s largest coal producer, Teck currently operates four surface coal mines in the Elk Valley stretching north of the Montana-Canada border in British Columbia.

FLBS research scientist Sexton said a fifth mine has been decommissioned but still actively leaches contaminants.

The main concern, selenium in the valley ultimately discharges into the transboundary Lake Koocanusa and underlying Kootenai River, into northern Idaho — also threatening decades-long efforts by the Kootenai Tribe of Idaho to restore healthy fish populations.

The Kootenai River then flows into Canada’s own Kootenay Lake.

Data over the past nearly four decades show a steady uptick of selenium concentrations, initially breaching Canada’s current 2 micrograms per liter guideline during the early 1990s, in the Elk River near its confluence with Koocanusa waters, according to the DEQ.

All data points from about 2010 to 2020 near the confluence exceeded Canada’s guideline, approaching or exceeding 8 micrograms per liter for the first time since about 2014, according to the department.

The Elk River overall delivers some 95% of the selenium entering Lake Koocanusa, according to the DEQ.

USGS data indicate that total reservoir selenium levels at the international border consistently, if not entirely, exceeded the state’s new site-specific 0.8 microgram per liter limit for Lake Koocanusa since at least 2019.

Total selenium levels in the reservoir during 2021 at the border ranged from about 1 to 1.5 micrograms with a record maximum of 1.95 micrograms set last year, according to the agency.

Fined $60 million last year by Canada for selenium and calcite discharges, the company recently announced making a third wastewater treatment facility operational in the Elk Valley, with a fourth expected.

Teck’s first treatment plant in the valley became operational in 2013, a venture fraught with issues, Sexton said.

“Unfortunately, the wastewater treatment plants have not been a success story,” she said.

Sexton noted issues like the first plant initially converting selenium into a more toxic form — actually furthering fish kills — and years-long delays in getting additional treatment plants fully operational in treating ever-present contaminants otherwise leaching from the mines.

“It’s very concerning that these mitigations are coming on-line in the pace that they are, with basically no regulatory response,” Sexton said.

Reporter John McLaughlin can be reached at 758-4439 or jmclaughlin@dailyinterlake.com

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Recent data spell trouble for Koocanusa fish