Selenium in the Kootenai River Basin, Montana and Idaho, United States, and British Columbia, Canada

Fact Sheet 2022-3033



Selenium entering the 90-mile long transboundary Koocanusa Reservoir (also called Lake Koocanusa) in southeastern British Columbia, Canada, and northwestern Montana, United States, has been measured at concentrations above State and Federal water-quality and aquatic life standards. The reservoir is within the international Kootenai (or “Kootenay” in Canada) drainage basin, which contains critical habitat for native fish species and is impounded by Libby Dam 16 miles upstream from Libby, Montana. Since 1984, selenium concentrations have ranged from below detection to greater than 8 micrograms per liter in the Elk River, measured 2.2 miles above its discharge into Koocanusa Reservoir at a British Columbia environmental monitoring station (site 0200016). Selenium is a required micro-nutrient, but elevated concentrations in water bioaccumulate in egg-laying fish and birds, causing various sublethal effects and death. One possible source of selenium in the Kootenai River Basin is the excavation of bedrock in the Elk River Valley to access coal seams for metallurgical steelmaking and coal production. Five open-pit coal mines are operating in this region of southeastern British Columbia that produce about 21 million tons of metallurgical coal annually.

Site-specific selenium standards were established for the reservoir in 2020 following collaborative work by the U.S. Geological Survey, Montana Department of Environmental Quality, the British Columbia Ministry of Environment and Climate Change Strategy, the Lake Koocanusa Monitoring and Research Working Group, and the Selenium Technical Subcommittee. The standards of 0.8 microgram per liter for dissolved selenium in the water column and 15.1 milligrams per kilogram dry weight for fish egg (ovary) tissue (in addition to the muscle and wholebody standards) were adopted into Montana State law in 2020 and approved by the U.S. Environmental Protection Agency in 2021.

Suggested Citation

U.S. Geological Survey, 2022, Selenium in the Kootenai River Basin, Montana and Idaho, United States, and British Columbia, Canada: U.S. Geological Survey Fact Sheet 2022–3033, 4 p.,

ISSN: 2327-6932 (online)

ISSN: 2327-6916 (print)

Study Area

Table of Contents

  • Introduction
  • Previous Work in the Kootenai River Basin
  • Ongoing and Future Work
  • References Cited
Publication type Report
Publication Subtype USGS Numbered Series
Title Selenium in the Kootenai River Basin, Montana and Idaho, United States, and British Columbia, Canada
Series title Fact Sheet
Series number 2022-3033
DOI 10.3133/fs20223033
Year Published 2022
Language English
Publisher U.S. Geological Survey
Publisher location Reston, VA
Contributing office(s) Wyoming-Montana Water Science Center
Description Report: 4 p.; Data Release; 3 Datasets
Country Canada, United States
State British Columbia, Idaho, Montana
Online Only (Y/N) N
Google Analytic Metrics Metrics page
Additional publication details