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 Municipal Affairs and Environment 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. This dataset also includes data from provincial sites covered under the Canada-NL Water Quality Monitoring Agreement. Data for additional sites are available from NL Municipal Affairs and Environment. Most recent data can be downloaded from the following link: http://data.ec.gc.ca/data/substances/monitor/national-long-term-water-quality-monitoring-data/newfoundland-and-labrador-long-term-water-quality-monitoring-data/$3lang=en