This data release contains five datasets that were used in a Scientific Investigations Report to be published in 2018. These datasets are continuous temperature data, temperature profiles data, SPMD environmental concentration data in picograms per liter of water, SPMD environmental concentration data in nanograms per SPMD, and SPMD quality-control concentration data. SPMD Environmental Concentration, Continuous Temperature and Temperature Profile: Semipermeable membrane devices (SPMDs) and Onset Computer Corporation® TidbiT v2 temperature loggers were deployed together at 8 locations within southern Lake Powell to collect water concentrations of polycyclic aromatic hydrocarbons (PAHs) and to collect continuous water temperature data. At these locations, the instruments were either deployed on a fixed dock, a buoy, or a floating dock. Listed below are the 8 locations that the SPMDs and the continuous temperature sensors were deployed. The PAH environmental concentration data are reported in both the original units, as nanograms per SPMD (ng/SPMD) and converted to a concentration in picograms per liter of water (pg/L). Temperature profile data were collected at all 8 locations. This data was collected during deployment and retrieval of the SPMDs by using a Sea-Bird Electronics, Inc., model SBE25 CTD profiler™. • Antelope Marina (USGS 365759111254700); Fixed Dock • Dangling Rope Marina (USGS 370708111045100); Fixed Dock • Lone Rock Beach (USGS 370107111320500); Buoy • Padre Bay near Dominquez Butte (USGS 370321111171700); Buoy • Rainbow Bridge National Monument (USGS 370506110581600); Fixed Dock • Stateline Marina (USGS 370031111300100); Fixed Dock • Wahweap Marina (USGS 365933111285200); Fixed Dock • Warm Creek Bay (USGS 370333111262700); Floating Dock SPMD environmental concentration data, and continuous temperature data were collected during the time periods listed below. Temperature profile data were collected at the time of deployment and the time of retrieval of the SPMDs. • June 21, 2016 (deployment date) to July 20, 2016 (retrieval date) • April 18, 2017 (deployment date) to May 16, 2017 (retrieval date) • June 29, 2017 (deployment date) to July 26, 2017 (retrieval date) SPMD Quality-control Concentrations: The following are the different types of quality-control data that were collected during the duration of this study: • Field Replicates • Field Blanks • Laboratory Blanks • Laboratory Fabrication Blanks • Laboratory Matrix Spikes • Performance Reference Compounds • Photolysis Marker

The data set contains temporal chloride concentrations (mg/L) and specific conductance (uS/cm) values for 32 wetlands and groundwater monitoring wells as well as the date(s) sampled and the laboratory where the water quality analyses were conducted. The ratio of chloride concentration to specific conductance is referred to as the Contamination Index. In this region, values greater than 0.035 are used to identify water quality samples that are contaminated with co-produced water from energy development.

The data set contains temporal chloride concentrations (mg/L) and specific conductance (uS/cm) values for 32 wetlands and groundwater monitoring wells as well as the date(s) sampled and the laboratory where the water quality analyses were conducted. The ratio of chloride concentration to specific conductance is referred to as the Contamination Index. In this region, values greater than 0.035 are used to identify water quality samples that are contaminated with co-produced water from energy development.

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.

This dataset is the basis for the U.S. Geological Survey Scientific Investigations Report "An evaluation of methods for computing annual water quality loads", which utilized available data from Heidelberg University and the U.S. Geological Survey to evaluate the accuracy of various methods for computing annual water-quality loads. This dataset contains two files used in the report: "QW_FLOW.csv", which contains the water-quality sample and streamflow data used to develop water-quality load estimates, and "QW_LOAD.csv", which contains observed and estimated annual loads.

This dataset is the basis for the U.S. Geological Survey Scientific Investigations Report "An evaluation of methods for computing annual water quality loads", which utilized available data from Heidelberg University and the U.S. Geological Survey to evaluate the accuracy of various methods for computing annual water-quality loads. This dataset contains two files used in the report: "QW_FLOW.csv", which contains the water-quality sample and streamflow data used to develop water-quality load estimates, and "QW_LOAD.csv", which contains observed and estimated annual loads.

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.

This data release is a compilation of information for hydrologic characteristics of groundwater and surface water within Clark County, South Dakota and around selected lakes (Dry Lake #1 and #2, and Antelope Lake). Information is organized into two broad categories (besides the folder for the Clark County ScienceBase landing page shapefile); reports and maps, and geographic information systems (GIS) data sources.