Long-term freshwater quality monitoring data for sites in Newfoundland and Labrador (NL) 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 Parks Canada. Environment and Climate Change Canada (ECCC) and with NL Environment and Conservation through the Canada-NL Water Quality Monitoring Agreement 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. Data for additional sites are available from NL Environment and Conservation.