This data release codifies and attributes explanatory factors that could potentially impact groundwater quality at 49 groundwater sites used for domestic water supply in the Sacramento Metropolitan Domestic-Supply Aquifer Study Unit (SacMetro-DSA). Water quality from domestic groundwater sites in the SacMetro-DSA was assessed as part of the California State Water Resources Control Board’s Groundwater Ambient Monitoring and Assessment (GAMA) program in 2017. The SacMetro-DSA study unit includes domestic wells within three Department of Water Resources defined groundwater subbasins; the North American, the South American, and the Cosumnes. Study design and site selection for the SacMetro-DSA study unit are detailed by Bennett and others (2019). Potential explanatory factors are attributed to domestic groundwater sites relating to: land use (percent agricultural, urban, and natural land use), underground storage and septic tank densities, hydrologic conditions (aridity index, elevation of the groundwater site), well construction (well depth, depth to the top of the open or perforated interval, well depth classification), groundwater age classification, and geochemical condition (groundwater redox classification, pH, dissolved oxygen). This data release contains a tab-delimited text file containing locations and potential explanatory factors for domestic groundwater sites in the SacMetro-DSA (Table 1). Additionally, an extensible markup language (XML) metadata file is included detailing process steps and references for attribution of potential explanatory factors to the groundwater sites. Bennett, G.L., V., Shelton, J.L., Watson, E., Johnson, T.D., and Jasper, M., 2019, Groundwater-quality data in the Sacramento Metro shallow aquifer study unit, 2017: Results from the California GAMA Priority Basin Project: U.S. Geological Survey data release Available at https://doi.org/10.5066/P9BPGEGH. These data support the following publications: Bennett, G.L. V, 2022, Status and Understanding of Groundwater Quality in the Sacramento Metropolitan Domestic-Supply Aquifer Study Unit, 2017: California GAMA Priority Basin Project: Geological Survey Scientific Investigations Report 2022–5021, 52 p., https://doi.org/10.3133/sir20225021.

This data release codifies and attributes explanatory factors that could potentially impact groundwater quality at 49 groundwater sites used for domestic water supply in the Sacramento Metropolitan Domestic-Supply Aquifer Study Unit (SacMetro-DSA). Water quality from domestic groundwater sites in the SacMetro-DSA was assessed as part of the California State Water Resources Control Board’s Groundwater Ambient Monitoring and Assessment (GAMA) program in 2017. The SacMetro-DSA study unit includes domestic wells within three Department of Water Resources defined groundwater subbasins; the North American, the South American, and the Cosumnes. Study design and site selection for the SacMetro-DSA study unit are detailed by Bennett and others (2019). Potential explanatory factors are attributed to domestic groundwater sites relating to: land use (percent agricultural, urban, and natural land use), underground storage and septic tank densities, hydrologic conditions (aridity index, elevation of the groundwater site), well construction (well depth, depth to the top of the open or perforated interval, well depth classification), groundwater age classification, and geochemical condition (groundwater redox classification, pH, dissolved oxygen). This data release contains a tab-delimited text file containing locations and potential explanatory factors for domestic groundwater sites in the SacMetro-DSA (Table 1). Additionally, an extensible markup language (XML) metadata file is included detailing process steps and references for attribution of potential explanatory factors to the groundwater sites. Bennett, G.L., V., Shelton, J.L., Watson, E., Johnson, T.D., and Jasper, M., 2019, Groundwater-quality data in the Sacramento Metro shallow aquifer study unit, 2017: Results from the California GAMA Priority Basin Project: U.S. Geological Survey data release Available at https://doi.org/10.5066/P9BPGEGH. These data support the following publications: Bennett, G.L. V, 2022, Status and Understanding of Groundwater Quality in the Sacramento Metropolitan Domestic-Supply Aquifer Study Unit, 2017: California GAMA Priority Basin Project: Geological Survey Scientific Investigations Report 2022–5021, 52 p., https://doi.org/10.3133/sir20225021.

The U.S. Geological Survey collected groundwater samples from 49 wells used for domestic and small system drinking water supplies in Amador, Placer, Sutter, and Sacramento Counties, California in 2017. The wells were sampled for the Sacramento Metropolitan (SacMetro) Shallow Aquifer Study Unit of the California State Water Resources Control Board Groundwater Ambient Monitoring and Assessment (GAMA) Program Priority Basin Project’s assessment of the quality of groundwater resources used for domestic and small system drinking water supplies. Domestic and small-system wells are commonly screened at shallower depths than public-supply wells. The SacMetro study unit consisted of three “study areas” corresponding to three California Department of Water Resources groundwater subbasins: the North American and South American subbasins of the Sacramento Valley groundwater basin, and the Cosumnes subbasin of the San Joaquin Valley groundwater basin. Wells in the SacMetro study unit were in alluvial aquifers composed of sediments derived from the Sierra Nevada Mountains east of the study unit. The study unit was divided into 56 approximately 58 square kilometer grid cells, and a domestic or small-system well was sampled in 49 of those cells. Groundwater samples from all 49 wells were analyzed for field water-quality parameters, volatile organic compounds, pesticides and pesticide degradates, nutrients, major ions and trace elements, arsenic speciation, chromium (VI), perchlorate, gross alpha and gross beta particle activities, sulfur hexafluoride, tritium, carbon-14 in dissolved inorganic carbon, noble gases, stable isotopic ratios of water and dissolved nitrate, and microbial indicators. Groundwater levels were measured in 44 of the 49 wells. All results are presented in this data release, except results for pesticide and pesticide degradates. In 2017, the U.S. Geological Survey National Water-Quality Assessment (NAWQA) Program sampled 22 monitoring wells located in the SacMetro study unit as part of ongoing NAWQA studies of groundwater quality in different land-use settings. Of the 22 wells, 21 were part of an urban land-use network and 1 was part of a rice land use network. Results for analyses of perchlorate, chromium (VI), and stable isotopic ratios are presented in this data release, and results for analyses of field water-quality parameters, volatile organic compounds, pesticide and pesticide degradates, nutrients, major ions and trace elements, dissolved organic carbon, and tritium will be presented in a data release to be published separately by NAWQA. This data release supports the following publication: Groundwater Quality in the Sacramento Metropolitan shallow aquifer, California: U.S. Geological Survey Open-File Report 2019-1047, 4p., https://doi.org/10.3133/ofr20191047.

The U.S. Geological Survey collected groundwater samples from 49 wells used for domestic and small system drinking water supplies in Amador, Placer, Sutter, and Sacramento Counties, California in 2017. The wells were sampled for the Sacramento Metropolitan (SacMetro) Shallow Aquifer Study Unit of the California State Water Resources Control Board Groundwater Ambient Monitoring and Assessment (GAMA) Program Priority Basin Project’s assessment of the quality of groundwater resources used for domestic and small system drinking water supplies. Domestic and small-system wells are commonly screened at shallower depths than public-supply wells. The SacMetro study unit consisted of three “study areas” corresponding to three California Department of Water Resources groundwater subbasins: the North American and South American subbasins of the Sacramento Valley groundwater basin, and the Cosumnes subbasin of the San Joaquin Valley groundwater basin. Wells in the SacMetro study unit were in alluvial aquifers composed of sediments derived from the Sierra Nevada Mountains east of the study unit. The study unit was divided into 56 approximately 58 square kilometer grid cells, and a domestic or small-system well was sampled in 49 of those cells. Groundwater samples from all 49 wells were analyzed for field water-quality parameters, volatile organic compounds, pesticides and pesticide degradates, nutrients, major ions and trace elements, arsenic speciation, chromium (VI), perchlorate, gross alpha and gross beta particle activities, sulfur hexafluoride, tritium, carbon-14 in dissolved inorganic carbon, noble gases, stable isotopic ratios of water and dissolved nitrate, and microbial indicators. Groundwater levels were measured in 44 of the 49 wells. All results are presented in this data release, except results for pesticide and pesticide degradates. In 2017, the U.S. Geological Survey National Water-Quality Assessment (NAWQA) Program sampled 22 monitoring wells located in the SacMetro study unit as part of ongoing NAWQA studies of groundwater quality in different land-use settings. Of the 22 wells, 21 were part of an urban land-use network and 1 was part of a rice land use network. Results for analyses of perchlorate, chromium (VI), and stable isotopic ratios are presented in this data release, and results for analyses of field water-quality parameters, volatile organic compounds, pesticide and pesticide degradates, nutrients, major ions and trace elements, dissolved organic carbon, and tritium will be presented in a data release to be published separately by NAWQA. This data release supports the following publication: Groundwater Quality in the Sacramento Metropolitan shallow aquifer, California: U.S. Geological Survey Open-File Report 2019-1047, 4p., https://doi.org/10.3133/ofr20191047.

This data release contains site information and potential explanatory factor data for 1,899 groundwater sites. These sites were used to assess groundwater quality in aquifers used for domestic and public drinking water supply in the southeastern San Joaquin Valley. The southeastern San Joaquin Valley (SESJV) study unit consists of five study areas whose boundaries are defined by the eponymous California Department of Water Resources groundwater subbasins of the San Joaquin Valley groundwater basin: Madera-Chowchilla, Kings, Kaweah, Tule, and Tulare Lake. The sites consist of 198 wells representing the domestic-supply aquifer and 1,701 wells representing the public-supply aquifer. The domestic-supply aquifer wells were sampled in 2013-2015 by the USGS for either the California Groundwater Ambient Monitoring and Assessment Program Priority Basin Project (GAMA-PBP) or the USGS National Water Quality Assessment project (NAWQA). The public-supply aquifer wells were either sampled by the USGS for the GAMA-PBP in 2005-2018 or have water-quality data in the California State Water Resources Control Board Division of Drinking Water (SWRCB-DDW) public database. The data types in this data release include site identification and location, well construction and lithology data, land use characteristics, groundwater age and oxidation-reduction classifications and aridity indices. Not all sites have data for all fields. Water-quality data for the sites are available from U.S. Geological Survey (2023), and California State Water Resources Control Board Division of Drinking Water (2023). The study design and the assessment results are presented in Burow and others (2024).

The U.S. Geological Survey collected groundwater samples from 38 wells used for domestic and small system drinking water supply in the Coachella Valley of California in 2020. The wells were sampled for the Coachella Valley Basin (CODA) Domestic Aquifer Study Unit of the California State Water Resources Control Board Groundwater Ambient Monitoring and Assessment (GAMA) Program Priority Basin Project’s assessment of the quality of groundwater resources used for domestic and small system drinking water supplies. Coachella Valley is located in the Desert hydrogeologic province (Johnson and Belitz, 2003) and is structurally divided into four subbasins by the San Andreas fault: the Indio subbasin, the Mission Creek subbasin, the Desert Hot Springs subbasin, and the San Gorgonio Pass subbasin (California Department of Water Resources, 2016). These basins have CA basin designations 7-21.01, 7-21.02, 7-21.03, and 7-21.04 respectively. The study area was divided into 30 equal-area grid cells with at least one well sampled in 26 of the 30 cells. The 10 understanding wells were selected to provide more data in areas where wells were more abundant and to provide more water quality data for wells in the State Small Water System program. In three cases, Sampled wells within 1 mile of an unsampled cell were used to represent unsampled grid cells. Groundwater samples from all 38 wells were analyzed for field water-quality parameters and microbial indicators, volatile organic compounds, pesticides and pesticide degradates, major ions and trace elements, chromium (VI), perchlorate, nutrients, carbon-14 in dissolved inorganic carbon, stable isotopic ratios of water, tritium, per- and polyfluoroalkyl substances (PFAS), sulfur hexafluoride, and noble gases. Groundwater levels were measured in 31 of the 38 wells. All results are presented in this data release, except results sulfur hexafluoride and noble gases. NOTE: The only difference between the original version of this data release and this version is that this data release includes results for tritium. Tritium results were not included in the original version because they were not available at the time of publication.

The U.S. Geological Survey collected groundwater samples from 38 wells used for domestic and small system drinking water supply in the Coachella Valley of California in 2020. The wells were sampled for the Coachella Valley Basin (CODA) Domestic Aquifer Study Unit of the California State Water Resources Control Board Groundwater Ambient Monitoring and Assessment (GAMA) Program Priority Basin Project’s assessment of the quality of groundwater resources used for domestic and small system drinking water supplies. Coachella Valley is located in the Desert hydrogeologic province (Johnson and Belitz, 2003) and is structurally divided into four subbasins by the San Andreas fault: the Indio subbasin, the Mission Creek subbasin, the Desert Hot Springs subbasin, and the San Gorgonio Pass subbasin (California Department of Water Resources, 2016). These basins have CA basin designations 7-21.01, 7-21.02, 7-21.03, and 7-21.04 respectively. The study area was divided into 30 equal-area grid cells with at least one well sampled in 26 of the 30 cells. This dataset identifies the well locations, study unit boundary, and grid cells for the Coachella Valley Domestic-Supply Aquifer study unit. Note: The only difference between the original version of this data release and this version is that this data release includes results for tritium. Tritium results were not included in the original version because they were not available at the time of publication.

The U.S. Geological Survey collected groundwater samples from 38 wells used for domestic and small system drinking water supply in the Coachella Valley of California in 2020. The wells were sampled for the Coachella Valley Basin (CODA) Domestic Aquifer Study Unit of the California State Water Resources Control Board Groundwater Ambient Monitoring and Assessment (GAMA) Program Priority Basin Project’s assessment of the quality of groundwater resources used for domestic and small system drinking water supplies. Coachella Valley is located in the Desert hydrogeologic province (Johnson and Belitz, 2003) and is structurally divided into four subbasins by the San Andreas fault: the Indio subbasin, the Mission Creek subbasin, the Desert Hot Springs subbasin, and the San Gorgonio Pass subbasin (California Department of Water Resources, 2016). These basins have CA basin designations 7-21.01, 7-21.02, 7-21.03, and 7-21.04 respectively. The study area was divided into 30 equal-area grid cells with at least one well sampled in 26 of the 30 cells. The 10 understanding wells were selected to provide more data in areas where wells were more abundant and to provide more water quality data for wells in the State Small Water System program. In three cases, Sampled wells within 1 mile of an unsampled cell were used to represent unsampled grid cells. Groundwater samples from all 38 wells were analyzed for field water-quality parameters and microbial indicators, volatile organic compounds, pesticides and pesticide degradates, major ions and trace elements, chromium (VI), perchlorate, nutrients, carbon-14 in dissolved inorganic carbon, stable isotopic ratios of water, tritium, per- and polyfluoroalkyl substances (PFAS), sulfur hexafluoride, and noble gases. Groundwater levels were measured in 31 of the 38 wells. All results are presented in this data release, except results sulfur hexafluoride and noble gases. NOTE: The only difference between the original version of this data release and this version is that this data release includes results for tritium. Tritium results were not included in the original version because they were not available at the time of publication.

The U.S. Geological Survey collected groundwater samples from 38 wells used for domestic and small system drinking water supply in the Coachella Valley of California in 2020. The wells were sampled for the Coachella Valley Basin (CODA) Domestic Aquifer Study Unit of the California State Water Resources Control Board Groundwater Ambient Monitoring and Assessment (GAMA) Program Priority Basin Project’s assessment of the quality of groundwater resources used for domestic and small system drinking water supplies. Coachella Valley is located in the Desert hydrogeologic province (Johnson and Belitz, 2003) and is structurally divided into four subbasins by the San Andreas fault: the Indio subbasin, the Mission Creek subbasin, the Desert Hot Springs subbasin, and the San Gorgonio Pass subbasin (California Department of Water Resources, 2016). These basins have CA basin designations 7-21.01, 7-21.02, 7-21.03, and 7-21.04 respectively. The study area was divided into 30 equal-area grid cells with at least one well sampled in 26 of the 30 cells. This dataset identifies the well locations, study unit boundary, and grid cells for the Coachella Valley Domestic-Supply Aquifer study unit. Note: The only difference between the original version of this data release and this version is that this data release includes results for tritium. Tritium results were not included in the original version because they were not available at the time of publication.

The U.S. Geological Survey collected groundwater samples from 38 wells used for domestic and small system drinking water supply in the Coachella Valley of California in 2020. The wells were sampled for the Coachella Valley Basin (CODA) Domestic Aquifer Study Unit of the California State Water Resources Control Board Groundwater Ambient Monitoring and Assessment (GAMA) Program Priority Basin Project’s assessment of the quality of groundwater resources used for domestic and small system drinking water supplies. Coachella Valley is located in the Desert hydrogeologic province (Johnson and Belitz, 2003) and is structurally divided into four subbasins by the San Andreas fault: the Indio subbasin, the Mission Creek subbasin, the Desert Hot Springs subbasin, and the San Gorgonio Pass subbasin (California Department of Water Resources, 2016). These basins have CA basin designations 7-21.01, 7-21.02, 7-21.03, and 7-21.04 respectively. The study area was divided into 30 equal-area grid cells with at least one well sampled in 26 of the 30 cells. This dataset identifies the well locations, study unit boundary, and grid cells for the Coachella Valley Domestic-Supply Aquifer study unit. Note: The only difference between the original version of this data release and this version is that this data release includes results for tritium. Tritium results were not included in the original version because they were not available at the time of publication.