International Effects and Impacts of Selenium, Nitrogen, and Phosphorus on the Kootenai River System

Abstract

The Kootenai River watershed, a transboundary system shared between British Columbia (Canada) and Montana and Idaho (United States), has been increasingly affected by nutrient and selenium pollution associated with historic and ongoing coal mining in the Elk River Valley. Elevated concentrations of selenium, nitrogen, and phosphorus have raised both ecological and policy concerns within this transboundary system. Therefore, my study analyzed nutrient and pollutant data collected by the U.S. Geological Survey (USGS) from 2019 to 2023 at three sampling sites: the Kootenai River below Libby Dam, near Libby, Montana; the Fisher River, near Libby, Montana; and the Yaak River, near Troy, Montana. I evaluated pollution trends of spatial and temporal nutrient loading patterns with simple linear regressions and single-factor ANOVA. My results indicate that the Kootenai River below Libby Dam exhibited the highest frequency and concentration of selenium samples, indicating upstream and dam-related influences. The Yaak River sampling site showed limited nutrient activity reflecting low monitoring effort on some monitoring stations and reduced anthropogenic impacts. Across the sampling sites, selenium was recorded more than the nitrogen and phosphorus, highlighting policy significance and the ongoing impacts of coal mining discharges entering Lake Koocanusa. Overall, my analysis supports the conclusion that selenium remains the most persistent transboundary pollutant of concern. Nitrogen and phosphorus concentrations suggest potential for trophic shifts toward mesotrophic or eutrophic conditions. Effective long-term management of the Kootenai watershed will require coordination between the governments of the United States and Canada. This includes stable USGS funding for consistent monitoring and policies that address both mining and agricultural nutrient pollution within the transboundary Kootenai watershed