Results from a water-quality sampling project on the Kootenai River indicate there are elevated levels of selenium in water and fish tissue and elevated nitrates in water — two findings the United States Environmental Protection Agency says are associated with upstream mining sources in Canada’s Elk Valley and at Lake Koocanusa.

The study, initiated by the EPA in 2018, was part of a collaborative effort among federal, state and tribal agencies to assess the Kootenai River watershed. The data, released by the EPA and U.S. Geological Survey on Monday, is based on water chemistry and fish tissue samples taken on the river in Montana and Idaho from immediately below Libby Dam to the Canadian border.

According to the results, samplings show “the Kootenai River is being impacted by upstream mining in British Columbia and points to the need for continued monitoring to assess Kootenai River health and to track future needs.”

Aside from looking at chemical levels in the water, the study evaluated 142 fish for selenium and mercury as well. A portion of those fish tested positive for selenium levels exceeding EPA criteria.

Selenium concentrations in water were found to be elevated, but did not exceed EPA-recommended criteria for selenium in flowing waters. The element was not detected in water samples from Kootenai River tributaries unaffected by discharge from Lake Koocanusa, which indicates “the source is the discharge from mine-related constituents at the lake.” The results also show nitrate was detected in water immediately below Libby Dam at nearly three times the concentrations observed in previous samples collected from 2000 to 2004 and significantly higher than those found in the tributaries.

“The results [of the recent sampling], particularly selenium impacts to fish, underscore the need for a more detailed understanding of water quality and continued collaboration to protect Lake Koocanusa and the Kootenai River,” said EPA Regional Administrator Gregory Sopkin.

EPA has engaged in efforts to address water-quality impacts to the lake. Data collection on selenium and nitrate concentrations began several decades ago.

Previous studies show most of the selenium and nitrate in the lake originates from four open-pit coal mines in British Columbia that are owned by Teck Resources. Montana DEQ has reported the coal that is mined by the company “resides deep within mountainous terrain along the Elk River Valley. From the coal comes selenium, which seeps into the Elk River, a tributary of the Kootenai River which forms Lake Koocanusa behind Libby Dam.

Researchers and members from surrounding communities, including Troy, Libby and Eureka, expressed concerns about the selenium levels long before the release of the Monday’s results.

In July, a scientist with the University of Montana’s Flathead Lake Biological Station who has studied the Elk River and selenium run-off for years, Erin Sexton, told the Daily Inter Lake “I have yet to see anywhere else the levels of selenium that we have in this system.”

Selenium is a naturally occurring element present in sedimentary rocks, shales, coal and phosphate deposits and soils. According to the EPA, “selenium bioaccumulates in the aquatic food chain and chronic exposure in fish and aquatic invertebrates can cause reproductive impairments.”

Moving forward, Montana DEQ, the British Columbia Ministry of Environment and Climate Change Strategies, the EPA and other parties are working together to develop site-specific water-quality criteria for selenium in Lake Koocanusa. The agencies hope to submit the criteria to EPA officials for review next year. The criteria will be in line with guidelines for selenium in water sources set by the EPA in 2016.

Reporter Kianna Gardner can be reached at 758-4407 or kgardner@dailyinterlake.com.