The U.S. Geological Survey (USGS) in cooperation with the California State Water Resources Control Board collected produced water and gas samples in the Poso Creek, Midway-Sunset, and Buena Vista Oil Fields in Kern County in 2020 and 2021. Sampled sites included oil wells; injectate from tanks, pipelines, and injection wells where produced water from many wells, after removal of oil, is stored or transported before underground injection; and integrated produced water from multiple oil wells collected from pipelines before oil removal. This digital dataset contains the site information, analyzing laboratories and methods, and water and gas chemistry and quality-control results for these samples. Chemistry results include concentrations of dissolved noble and hydrocarbon gases and their isotopic composition; concentrations of inorganic constituents including salinity, major and minor ions, trace elements, and nutrients; dissolved organic carbon and optical properties of dissolved organic carbon; stable isotopes of water, strontium dissolved in water, and carbon in dissolved inorganic carbon; and radium isotopes. Samples were analyzed in the field and by eight laboratories operated or contracted by the USGS.

The California State Water Resources Control Board (State Water Board) initiated the Oil and Gas Regional Monitoring Program (RMP) to assess effects of oil and gas development on groundwater designated for any beneficial use. The U.S. Geological Survey (USGS) is the technical lead in conducting the RMP through the California Oil, Gas, and Groundwater (COGG) Program, working in cooperation with the State Water Board, and in partnership with other State and local agencies. The USGS collected and analyzed groundwater, surface water, and associated quality control (QC) samples in the Poso Creek Oil Field study area during February 2020-December 2021. Groundwater samples were collected from eleven irrigation, two domestic, two public supply, four monitoring wells, two institutional wells, and two surface water sites located within a five km buffer zone surrounding the Poso Creek Oil Field in Kern County, California. Samples were collected using established groundwater data-collection protocols and procedures. Samples were analyzed for water-quality indicators, major and minor ions, nutrients, trace elements, volatile organic compounds (VOCs), naturally occurring radioactive material, geochemical and age-dating tracers, dissolved organic carbon (DOC), dissolved standard and hydrocarbon gases (methane through hexane), and dissolved noble gasses, atmospheric gases, and surrogates. Approximately two hundred and eight constituents and water-quality indicators were measured. QC samples analyzed as part of the Poso Creek Oil Field study included replicates, source-solution blanks, field and equipment blanks, and laboratory spikes and surrogates.

The California State Water Resources Control Board (State Water Board) initiated the Oil and Gas Regional Monitoring Program (RMP) to assess effects of oil and gas development on groundwater designated for any beneficial use. The U.S. Geological Survey (USGS) is the technical lead in conducting the RMP through the California Oil, Gas, and Groundwater (COGG) Program, working in cooperation with the State Water Board, and in partnership with other State and local agencies. The USGS collected and analyzed groundwater, surface water, and associated quality control (QC) samples in the Poso Creek Oil Field study area during February 2020-December 2021. Groundwater samples were collected from eleven irrigation, two domestic, two public supply, four monitoring wells, two institutional wells, and two surface water sites located within a five km buffer zone surrounding the Poso Creek Oil Field in Kern County, California. Samples were collected using established groundwater data-collection protocols and procedures. Samples were analyzed for water-quality indicators, major and minor ions, nutrients, trace elements, volatile organic compounds (VOCs), naturally occurring radioactive material, geochemical and age-dating tracers, dissolved organic carbon (DOC), dissolved standard and hydrocarbon gases (methane through hexane), and dissolved noble gasses, atmospheric gases, and surrogates. Approximately two hundred and eight constituents and water-quality indicators were measured. QC samples analyzed as part of the Poso Creek Oil Field study included replicates, source-solution blanks, field and equipment blanks, and laboratory spikes and surrogates.

The California State Water Resources Control Board (State Water Board) initiated the Oil and Gas Regional Monitoring Program (RMP) to assess effects of oil and gas development on groundwater (GW) designated for any beneficial use. The U.S. Geological Survey (USGS) is the technical lead in conducting the RMP through the California Oil, Gas, and Groundwater (COGG) Program, working in cooperation with the State Water Board, and in partnership with other State and local agencies. The USGS collected and analyzed groundwater and associated quality control (QC) samples in the Midway-Sunset and Buena Vista Oil Fields (MSBV) study area during March 2018 - April 2019. Groundwater samples were collected from seven irrigation, one domestic, and ten monitoring wells located within and near the administrative boundaries of the Midway-Sunset and Buena Vista Oil Fields in Kern County, California. Samples were collected using established groundwater data-collection protocols and procedures. Samples were analyzed for water-quality indicators, major and minor ions, nutrients, trace elements, volatile organic compounds (VOCs), naturally occurring radioactive material, geochemical and age-dating tracers, dissolved organic carbon (DOC), dissolved standard and hydrocarbon gases (methane through hexane), and dissolved noble and atmospheric gases. Two hundred and twenty constituents and water-quality indicators were measured; one hundred and twenty are reported here. QC samples collected as part of the Midway-Sunset and Buena Vista Oil Fields study included replicates, source-solution blanks, field blanks, and laboratory spikes.

The California State Water Resources Control Board (State Water Board) initiated the Oil and Gas Regional Monitoring Program (RMP) to assess effects of oil and gas development on groundwater (GW) designated for any beneficial use. The U.S. Geological Survey (USGS) is the technical lead in conducting the RMP through the California Oil, Gas, and Groundwater (COGG) Program, working in cooperation with the State Water Board, and in partnership with other State and local agencies. The USGS collected and analyzed groundwater and associated quality control (QC) samples in the Midway-Sunset and Buena Vista Oil Fields (MSBV) study area during March 2018 - April 2019. Groundwater samples were collected from seven irrigation, one domestic, and ten monitoring wells located within and near the administrative boundaries of the Midway-Sunset and Buena Vista Oil Fields in Kern County, California. Samples were collected using established groundwater data-collection protocols and procedures. Samples were analyzed for water-quality indicators, major and minor ions, nutrients, trace elements, volatile organic compounds (VOCs), naturally occurring radioactive material, geochemical and age-dating tracers, dissolved organic carbon (DOC), dissolved standard and hydrocarbon gases (methane through hexane), and dissolved noble and atmospheric gases. Two hundred and twenty constituents and water-quality indicators were measured; one hundred and twenty are reported here. QC samples collected as part of the Midway-Sunset and Buena Vista Oil Fields study included replicates, source-solution blanks, field blanks, and laboratory spikes.

The California State Water Resources Control Board (State Water Board) initiated the Oil and Gas Regional Monitoring Program (RMP) to assess effects of oil and gas development on groundwater designated for any beneficial use. The U.S. Geological Survey (USGS) is the technical lead in conducting the RMP through the California Oil, Gas, and Groundwater (COGG) Program, working in cooperation with the State Water Board, and in partnership with other State and local agencies. The USGS collected and analyzed groundwater (GW) and surface water (SW) for the San Ardo Oil Field study area, the area within the San Ardo Oil Field administrative boundary and the surrounding five-kilometer buffer zone, in Monterey County, California. Eighteen groundwater, two stream, and two spring samples were collected from March 2019 through May 2021. Groundwater samples were collected from one public-supply well, five monitoring wells, two irrigation wells, one livestock well, five oil-field water supply wells, and four domestic wells. Samples were collected using established water data-collection protocols and procedures and analyzed for (1) water-quality indicators, (2) major and minor ions, (3) nutrients, (4) trace elements, (5) volatile organic compounds (VOCs), (6) naturally-occurring radioactive material (radium isotopes), (7) geochemical and age-dating tracers, (8) dissolved organic carbon (DOC), (9) dissolved standard and hydrocarbon gases (methane through hexane), and (10) dissolved noble gases and atmospheric gases. In total, 185 constituents, water-quality indicators, or properties are included in this data release. Quality-control (QC) samples were used to assess the quality of laboratory results.

The California State Water Resources Control Board (State Water Board) initiated the Oil and Gas Regional Monitoring Program (RMP) to assess effects of oil and gas development on groundwater designated for any beneficial use. The U.S. Geological Survey (USGS) is the technical lead in conducting the RMP through the California Oil, Gas, and Groundwater (COGG) Program, working in cooperation with the State Water Board, and in partnership with other State and local agencies. The USGS collected and analyzed groundwater (GW) and surface water (SW) for the San Ardo Oil Field study area, the area within the San Ardo Oil Field administrative boundary and the surrounding five-kilometer buffer zone, in Monterey County, California. Eighteen groundwater, two stream, and two spring samples were collected from March 2019 through May 2021. Groundwater samples were collected from one public-supply well, five monitoring wells, two irrigation wells, one livestock well, five oil-field water supply wells, and four domestic wells. Samples were collected using established water data-collection protocols and procedures and analyzed for (1) water-quality indicators, (2) major and minor ions, (3) nutrients, (4) trace elements, (5) volatile organic compounds (VOCs), (6) naturally-occurring radioactive material (radium isotopes), (7) geochemical and age-dating tracers, (8) dissolved organic carbon (DOC), (9) dissolved standard and hydrocarbon gases (methane through hexane), and (10) dissolved noble gases and atmospheric gases. In total, 185 constituents, water-quality indicators, or properties are included in this data release. Quality-control (QC) samples were used to assess the quality of laboratory results.

The California State Water Resources Control Board (State Water Board) initiated the Regional Groundwater Monitoring Program (RMP) to assess effects of oil and gas development on groundwater designated for any beneficial use. The U.S. Geological Survey (USGS) is the technical lead in conducting the RMP through the California Oil, Gas, and Groundwater (COGG) Program, working in cooperation with the State Water Board, and in partnership with other State and local agencies. The USGS collected and analyzed groundwater and associated quality control (QC) samples during September 2014 through October 2018. Groundwater samples collected in 2017-18 were from eight public supply wells, eight monitoring wells and one irrigation well located within the Montebello Oil Field study area, a three-mile buffer zone overlying and surrounding the Montebello Oil Field administrative boundary in Los Angeles County, California. Groundwater from four additional monitoring wells was collected in the Montebello Oil Field study area as part of the exploratory phase of the RMP; those sites were sampled in 2014. Samples were collected using established groundwater data-collection protocols and procedures. Samples were analyzed for water-quality indicators, major and minor ions; nutrients; trace elements, volatile organic compounds (VOCs) and semi-volatile organic compounds (SVOCs); naturally-occurring radioactive material; geochemical and age-dating tracers; dissolved organic carbon (DOC) characteristics; dissolved standard and hydrocarbon gases (methane through hexane); and dissolved noble gases and atmospheric gases. In total, 286 constituents, water-quality indicators, or properties were measured. QC samples collected as part of the Montebello Oil Field study area include one replicate, two equipment blanks and two source-solution blanks. Additional QC samples collected from study areas for which sampling was done during December 2017 through October 2018 include three replicates, three spikes, two field blanks, and two source-solution blanks.

The California State Water Resources Control Board (State Water Board) initiated the Regional Groundwater Monitoring Program (RMP) to assess effects of oil and gas development on groundwater designated for any beneficial use. The U.S. Geological Survey (USGS) is the technical lead in conducting the RMP through the California Oil, Gas, and Groundwater (COGG) Program, working in cooperation with the State Water Board, and in partnership with other State and local agencies. The USGS collected and analyzed groundwater and associated quality control (QC) samples during September 2014 through October 2018. Groundwater samples collected in 2017-18 were from eight public supply wells, eight monitoring wells and one irrigation well located within the Montebello Oil Field study area, a three-mile buffer zone overlying and surrounding the Montebello Oil Field administrative boundary in Los Angeles County, California. Groundwater from four additional monitoring wells was collected in the Montebello Oil Field study area as part of the exploratory phase of the RMP; those sites were sampled in 2014. Samples were collected using established groundwater data-collection protocols and procedures. Samples were analyzed for water-quality indicators, major and minor ions; nutrients; trace elements, volatile organic compounds (VOCs) and semi-volatile organic compounds (SVOCs); naturally-occurring radioactive material; geochemical and age-dating tracers; dissolved organic carbon (DOC) characteristics; dissolved standard and hydrocarbon gases (methane through hexane); and dissolved noble gases and atmospheric gases. In total, 286 constituents, water-quality indicators, or properties were measured. QC samples collected as part of the Montebello Oil Field study area include one replicate, two equipment blanks and two source-solution blanks. Additional QC samples collected from study areas for which sampling was done during December 2017 through October 2018 include three replicates, three spikes, two field blanks, and two source-solution blanks.

The California State Water Resources Control Board (State Water Board) initiated the Oil and Gas Regional Monitoring Program (RMP) to assess effects of oil and gas development on groundwater designated for any beneficial use. The U.S. Geological Survey (USGS) is the technical lead in conducting the RMP through the California Oil, Gas, and Groundwater (COGG) Program, working in cooperation with the State Water Board, and in partnership with other State and local agencies. The USGS collected and analyzed groundwater and associated quality control (QC) samples for an RMP study of the Santa Fe Springs (SFSP) Oil Field during April 2021 through April 2024. Groundwater samples collected in 2021-2024 were from twenty-seven monitoring wells, two irrigation wells, three public supply wells and a fire hydrant located within the Santa Fe Springs Oil Field study area. Samples were collected using established groundwater data-collection protocols and procedures. Samples were analyzed for water-quality indicators, major and minor ions, nutrients, trace elements, volatile organic compounds (VOCs), naturally-occurring radioactive material, geochemical and age-dating tracers, dissolved organic carbon (DOC) characteristics, dissolved standard and hydrocarbon gases, and dissolved noble gases and atmospheric gases. In total, 261 constituents, water-quality indicators, or properties were measured. QC samples analyzed for the Santa Fe Springs Oil Field study area include five field blanks, one equipment blank, six VOC source solution blanks, four replicates, and four VOC spikes.