An investigation was done by the U.S. Geological Survey, in cooperation with the California State Water Resources Control Board's Program of Regional Groundwater Monitoring of Water Quality in Areas of Oil and Gas Production, to assess the effects of oil and gas production activities on nearby groundwater resources. During November 2016–September 2017, 30 samples were collected at groundwater wells and 1 sample was collected at a surface-water site. This dataset contains site information and water chemistry results for samples collected near the Lost Hills and North and South Belridge oil fields, Kern County, California. Samples were analyzed for water-quality indicators, major and minor ions, nutrients, trace elements, volatile organic compounds, naturally occurring radioactive material, geochemical and age-dating tracers, dissolved organic carbon, low molecular weight organic acids, dissolved standard and hydrocarbon gases, and dissolved noble and atmospheric gases. Quality-control samples including replicates; source-solution, equipment, and field blanks; laboratory spikes; and split samples for interlab comparisons were collected and summarized in this data release.

An investigation was done by the U.S. Geological Survey, in cooperation with the California State Water Resources Control Board's Program of Regional Groundwater Monitoring of Water Quality in Areas of Oil and Gas Production, to assess the effects of oil and gas production activities on nearby groundwater resources. During November 2016–September 2017, 30 samples were collected at groundwater wells and 1 sample was collected at a surface-water site. This dataset contains site information and water chemistry results for samples collected near the Lost Hills and North and South Belridge oil fields, Kern County, California. Samples were analyzed for water-quality indicators, major and minor ions, nutrients, trace elements, volatile organic compounds, naturally occurring radioactive material, geochemical and age-dating tracers, dissolved organic carbon, low molecular weight organic acids, dissolved standard and hydrocarbon gases, and dissolved noble and atmospheric gases. Quality-control samples including replicates; source-solution, equipment, and field blanks; laboratory spikes; and split samples for interlab comparisons were collected and summarized in this data release.

An investigation was done by the U.S. Geological Survey, in cooperation with the California State Water Resources Control Board's Program of Regional Groundwater Monitoring of Water Quality in Areas of Oil and Gas Production, to assess the effects of oil and gas production activities on nearby groundwater resources. During November 2016–September 2017, 30 samples were collected at groundwater wells and 1 sample was collected at a surface-water site. This dataset contains site information and water chemistry results for samples collected near the Lost Hills and North and South Belridge oil fields, Kern County, California. Samples were analyzed for water-quality indicators, major and minor ions, nutrients, trace elements, volatile organic compounds, naturally occurring radioactive material, geochemical and age-dating tracers, dissolved organic carbon, low molecular weight organic acids, dissolved standard and hydrocarbon gases, and dissolved noble and atmospheric gases. Quality-control samples including replicates; source-solution, equipment, and field blanks; laboratory spikes; and split samples for interlab comparisons were collected and summarized in this data release.

An investigation was done by the U.S. Geological Survey, in cooperation with the California State Water Resources Control Board's Program of Regional Groundwater Monitoring of Water Quality in Areas of Oil and Gas Production, to assess the effects of oil and gas production activities on nearby groundwater resources. During November 2016–September 2017, 30 samples were collected at groundwater wells and 1 sample was collected at a surface-water site. This dataset contains site information and water chemistry results for samples collected near the Lost Hills and North and South Belridge oil fields, Kern County, California. Samples were analyzed for water-quality indicators, major and minor ions, nutrients, trace elements, volatile organic compounds, naturally occurring radioactive material, geochemical and age-dating tracers, dissolved organic carbon, low molecular weight organic acids, dissolved standard and hydrocarbon gases, and dissolved noble and atmospheric gases. Quality-control samples including replicates; source-solution, equipment, and field blanks; laboratory spikes; and split samples for interlab comparisons were collected and summarized in this data release.

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 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.

This dataset contains geochemical and other information for 268 samples of produced water from the Lost Hills and North and South Belridge Oil Fields. Produced water is water coexisting with oil and gas. The historical produced water chemistry data was compiled from preexisting datasets and scanned images into a numerical dataset to characterize produced water chemical characteristics. Each sample is identified by its API (American Petroleum Institute) number, excluding the state code, which is 04 in all California wells, latitude and longitude, well name, formation name, perforation interval, and date tested. The geochemical analyses include major ions, some minor ions, total dissolved solids (TDS), pH, specific gravity, resistivity, electrical conductivity, and charge balance.

This dataset contains geochemical and other information for 268 samples of produced water from the Lost Hills and North and South Belridge Oil Fields. Produced water is water coexisting with oil and gas. The historical produced water chemistry data was compiled from preexisting datasets and scanned images into a numerical dataset to characterize produced water chemical characteristics. Each sample is identified by its API (American Petroleum Institute) number, excluding the state code, which is 04 in all California wells, latitude and longitude, well name, formation name, perforation interval, and date tested. The geochemical analyses include major ions, some minor ions, total dissolved solids (TDS), pH, specific gravity, resistivity, electrical conductivity, and charge balance.