Concentrations of inorganic constituents, dissolved organic carbon (DOC), tritium, per- and polyfluoroalkyl substances (PFAS), volatile organic compounds (VOCs), and pharmaceuticals were measured in groundwater samples collected from 254 wells in 2019 and 2020. Concentrations of inorganic constituents, DOC, VOCs, and pharmaceuticals were measured at the U.S. Geological Survey (USGS) National Water Quality Laboratory in Lakewood, Colorado. Concentrations of tritium were measured at the USGS Tritium Laboratory in Menlo Park, California. Concentrations of PFAS were measured at SGS Laboratory in Orlando, Florida. In addition, several geospatial parameters were determined, including: percentages of selected land uses within 500-meter buffers around sampled wells, nitrogen loading from septic systems within 500-meter buffers around sampled wells, distance to nearest wastewater treatment plant, and distance to selected industry and other potential point sources that could be sources of PFAS to the environment. The data were collected as part of the USGS National Water-Quality (NAWQA) project. This data release contains 12 tables of well information, laboratory results, geospatial output, and a data dictionary, including: 1) PFAS_Data_Dictionary.csv – Parameters in each table are defined in this table. 2) PFAS_BLANK.csv – Concentrations of PFAS in equipment, field, and source-solution blank samples. 3) PFAS_ENV.csv – Concentrations of PFAS in environmental samples. 4) PFAS_GEOSPATIAL.csv – Percentages of selected land uses within 500-meter buffers around sampled wells; nitrogen loading from septic systems within 500-meter buffers around sampled wells; distance to nearest wastewater treatment plant; distance to selected industry and other potential point sources that could be sources of PFAS to the environment. 5) PFAS_INORGANICS_AND_OTHER.csv – Concentration of inorganic constituents, DOC, and tritium. 6) PFAS_LAB_BLANK.csv – Concentrations of PFAS in laboratory blank samples. 7) PFAS_PHARMA.csv – Concentrations of pharmaceutical compounds in environmental samples. 8) PFAS_REP.csv – Concentrations of PFAS in replicate samples. 9) PFAS_SPIKE_FIELD.csv – Percent recovery for PFAS in field matrix-spike samples. 10) PFAS_SPIKE_LAB.csv – Percent recovery for PFAS in laboratory reagent-spike and matrix-spike samples. 11) PFAS_VOCs.csv – Concentrations of VOCs in environmental samples. 12) PFAS_WELLS.csv – Site characteristics of the sampled wells.