Leading researchers tracking the influx of mining contaminants in Lake Koocanusa have developed a modeling framework designed to guide water quality standards on the sprawling trans-boundary reservoir, which is increasingly threatened by Canadian coalmines.
Lake Koocanusa spans the U.S.-Canada border and hosts a unique suite of aquatic species, as well as a robust recreation economy. But the reservoir’s waters and its fish species are imperiled due to increased levels of the mining contaminant selenium, a naturally occurring element in sedimentary rocks that can be toxic to fish at elevated levels, which are exacerbated by upstream mining operations and the accumulation of waste rock.
Scientists with the U.S. Geological Survey (USGS) this week released a modeling framework for scientific collection and analysis of selenium data in Lake Koocanusa in Northwest Montana and British Columbia — essentially an ecologic flowchart showing how and at what levels the contaminant affects waters and fish species.
The modeling framework, funded by the state Department of Environmental Quality (DEQ), is designed to accommodate existing and future data to support a site-specific standard for selenium in the Lake Koocanusa reservoir, which extends 90 miles from Libby Dam, 40 miles of which are north of the border in British Columbia, where coal mines.
“As a lead agency for Montana, we are excited to have this scientific tool to collect pertinent data,” Tim Davis, DEQ’s water quality administrator, said. “This framework allows us to work on both sides of the border as we collect defensible and important information that will help lead to informed standards for selenium as a critical step in the protection of Montana’s water quality.”
Selenium levels in the lake have been rising over the past decade, largely due to metallurgical coal mining in southeastern British Columbia, along the Elk River Valley, which spills into the Kootenay River (spelled Kootenai in the U.S.) at Lake Koocanusa.
Montana DEQ and the B.C. Ministry of the Environment have collaborated in recent years to develop a common, trans-boundary water quality standard for selenium to protect aquatic life in the lake. The USGS modeling framework is designed to accommodate data collection from numerous state, federal, and provincial agencies on both sides of the border.
Sensitive fish species like cutthroat and bull trout, as well as burbot and mountain whitefish, are listed in the framework with seasonal recommendations for selenium sampling, as well as water column monitoring protocols depending on the season. The modeling framework for selenium has been tested elsewhere over the past 10 years by the USGS and is tailored for specific conditions in Lake Koocanusa.
The authors of the modeling framework, David Naftz, Theresa Presser and Karen Jenni, are ranked among the foremost experts on selenium in the country.
Selenium is a micronutrient that in small quantities is essential to biological functions in animals and certain plants, but at critical levels adversely affects a broad range of aquatic life.
Based on data compiled by the USGS and DEQ, annual selenium loads entering Lake Koocanusa have increased from 2,600 kilograms in 1992 to more than 13,000 kg in 2012, representing more than a fivefold increase over the course of 20 years.
According to Montana Fish, Wildlife and Parks, muscle-tissue samples from seven species of fish in Lake Koocanusa collected in 2008 and again in 2013 show increasing trends in elevated selenium levels; moreover, the inrush of selenium won’t abate even if the mining operations shut down production, such is the scope of the footprint and the size of waste-rock piles leaching into the waterways.
During the five-year period between 2008 and 2013, Trevor Selch, a water pollution biologist for FWP, tracked increases of selenium in muscle-tissue concentrations at rates of between 21 and 70 percent, a trend he described as “alarming.”
The Montana DEQ has identified Lake Koocanusa as impaired by selenium and has listed the water body under the Clean Water Act.
To address the problem, Montana DEQ and the B.C. Ministry of the Environment have formed the Lake Koocanusa Monitoring and Research Working Group, which includes selenium experts from around the world.
Southern British Columbia has large reserves of high-grade coal, which is mined and shipped globally for steel making by the global company Teck Resources.
According to DEQ, developing a bi-national selenium standard will provide British Columbia’s regulatory agencies with better information to establish protective strategies for the lake.
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