The Koocanusa Reservoir (also called Lake Koocanusa) is a transboundary reservoir that's located in northwestern Montana and southwestern British Columbia, Canada (BC) and encompasses the headwaters of the Kootenai watershed, eventually flowing into the Columbia River. Coal mining has occurred in the Elk River watershed in British Columbia, Canada for more than 100 years. Concentrations of different constituents have been increasing in the Elk River below the mining operations since they were first measured in the 1970’s and 1980’s.
Evaluating Water Quality of Streamflow into Koocanusa Reservoir
The three largest tributaries to Koocanusa Reservoir are located in British Columbia, with Elk River being the second largest. Several, large scale, open pit coal mines are located in Elk River Valley. The U.S. Geological Survey began a study in 2020 to describe changes in concentrations of selenium, nitrate, and sulfate into the Koocanusa Reservoir. The study evaluated trends in concentrations of these three compounds and compared the results in the Elk River to trends in the Kootenay River. The Kootenay River is a similar watershed but does not have coal mining within the watershed. By comparing the water quality of these two rivers that primarily differ by the coal mining activity in the watershed, we can learn about how the mining is affecting the water.
Concentrations of Compounds Increasing in Elk River
Concentrations of selenium, nitrate, and sulfate in Elk River were evaluated using a variety of statistical methods and results show that concentrations of these constituents have increased over the last 40 years since data have been collected. By comparing trends to the Kootenay River, it can be determined that the increases in the Elk River are largely driven by mining.
Comparing Concentrations to Water Quality Regulations
Concentrations of selenium, nitrate, and sulfate in Lake Koocanusa now commonly exceed water-quality regulations in both the United States and Canada, which are different. The links to specific regulations for each country can be found on this page.
Below are related details on regulations.
Selected Water-Quality Regulation Resources for the Koocanusa Watershed in the United States and Canada
- Overview
The Koocanusa Reservoir (also called Lake Koocanusa) is a transboundary reservoir that's located in northwestern Montana and southwestern British Columbia, Canada (BC) and encompasses the headwaters of the Kootenai watershed, eventually flowing into the Columbia River. Coal mining has occurred in the Elk River watershed in British Columbia, Canada for more than 100 years. Concentrations of different constituents have been increasing in the Elk River below the mining operations since they were first measured in the 1970’s and 1980’s.
Sources/Usage: Public Domain.Open-pit mining has created tailings piles over 100 meters tall in the Elk River Valley.
Sources/Usage: Public Domain.Study area map showing Kootenai Basin including the Elk River and Kootenay River Watersheds. River segments that drain to the sampling locations are shown with thicker lines. Mine areas in the Elk River Watershed are shown in yellow. Evaluating Water Quality of Streamflow into Koocanusa Reservoir
The three largest tributaries to Koocanusa Reservoir are located in British Columbia, with Elk River being the second largest. Several, large scale, open pit coal mines are located in Elk River Valley. The U.S. Geological Survey began a study in 2020 to describe changes in concentrations of selenium, nitrate, and sulfate into the Koocanusa Reservoir. The study evaluated trends in concentrations of these three compounds and compared the results in the Elk River to trends in the Kootenay River. The Kootenay River is a similar watershed but does not have coal mining within the watershed. By comparing the water quality of these two rivers that primarily differ by the coal mining activity in the watershed, we can learn about how the mining is affecting the water.
Concentrations of Compounds Increasing in Elk River
Concentrations of selenium, nitrate, and sulfate in Elk River were evaluated using a variety of statistical methods and results show that concentrations of these constituents have increased over the last 40 years since data have been collected. By comparing trends to the Kootenay River, it can be determined that the increases in the Elk River are largely driven by mining.
Comparing Concentrations to Water Quality Regulations
Concentrations of selenium, nitrate, and sulfate in Lake Koocanusa now commonly exceed water-quality regulations in both the United States and Canada, which are different. The links to specific regulations for each country can be found on this page.
- Science
Below are related details on regulations.
Selected Water-Quality Regulation Resources for the Koocanusa Watershed in the United States and Canada
The United States, Canada, the States of Montana and Idaho, and Province of British Columbia all have different regulatory levels for the selenium, nitrate, and sulfate that affect the rivers and lakes in the Kootenei Basin. Links to those entities’ web pages describing the different regulations are provided to help provide perspective to the results of this study. - Data
- Publications