Long-term freshwater quality monitoring data for Rainy River / Lake of the Woods Watershed for the past 15 years or longer for nutrients, metals, major ions, and other physical-chemical variables are included in this dataset. Monitoring is conducted by Environment and Climate Change Canada (ECCC) to assess water quality status and long-term trends, detect emerging issues, establish water quality guidelines and track the effectiveness of remedial measures and regulatory decisions. The information informs and supports the Fresh Water Action Plan.