These data are chemical analyses of discrete samples of groundwater, stream base flow, and springs collected to support a U.S. Geological Survey study to estimate the timing and source of recharge to the basalt groundwater system in the Umatilla River basin, Oregon. Categories of data include: (1) site information (2) field measurements, (3) tracers of groundwater age and source, and (4) dissolved noble gases. These data were collected during August 26, 2014 – September 13, 2022. Data are in .csv file format.

This U.S. Geological Survey (USGS) data release contains data from stream water, groundwater, and soil samples collected in 2019 and 2020 in the North Quartz Creek watershed in central Colorado. Fourteen streambank wells were installed in pairs at seven locations in August 2020 to capture the emerging groundwater from the left bank and right banks (relative to downstream-facing direction) and a synoptic sampling campaign was conducted to quantify metal contributions to the stream. A continuous, instream injection of sodium bromide (NaBr) was initiated at the head of the 5 km study reach several days prior to the synoptic sampling campaign and maintained throughout the duration of the study. Bromide concentrations were subsequently used to determine streamflow in the primary study reach (upper 1.3 km) using the tracer-dilution method, and as an indicator of hydrologic connections between North Quartz Creek and subsurface water. Streamflow was quantified in a secondary study reach (lower 3.7 km) using data from a series of sodium chloride slug additions wherein specific conductivity readings were used as a surrogate for the tracer concentration. Surface water samples were collected along North Quartz Creek including inflows from the left (LBI) and right (RBI) banks. Soil and sediment samples were collected along the transport path from source material (natural weathering and mine tailings/mine drainage) to the stream.

This U.S. Geological Survey (USGS) data release contains data from stream water, groundwater, and soil samples collected in 2019 and 2020 in the North Quartz Creek watershed in central Colorado. Fourteen streambank wells were installed in pairs at seven locations in August 2020 to capture the emerging groundwater from the left bank and right banks (relative to downstream-facing direction) and a synoptic sampling campaign was conducted to quantify metal contributions to the stream. A continuous, instream injection of sodium bromide (NaBr) was initiated at the head of the 5 km study reach several days prior to the synoptic sampling campaign and maintained throughout the duration of the study. Bromide concentrations were subsequently used to determine streamflow in the primary study reach (upper 1.3 km) using the tracer-dilution method, and as an indicator of hydrologic connections between North Quartz Creek and subsurface water. Streamflow was quantified in a secondary study reach (lower 3.7 km) using data from a series of sodium chloride slug additions wherein specific conductivity readings were used as a surrogate for the tracer concentration. Surface water samples were collected along North Quartz Creek including inflows from the left (LBI) and right (RBI) banks. Soil and sediment samples were collected along the transport path from source material (natural weathering and mine tailings/mine drainage) to the stream.

This point dataset contains geologic information concerning regolith thickness and top-of-bedrock altitude at selected well and test-hole locations in the Lower Gunnison River Basin in Delta, Montrose, Ouray, and Gunnison Counties, Colorado. Regolith-thickness data were compiled from lithologic logs of wells and boreholes reported by the Colorado Division of Water Resources, U.S. Geological Survey, and Bureau of Reclamation. Bedrock-altitude values were computed from the bedrock altitude raster dataset (bralt). The U.S. Geological Survey prepared this dataset in cooperation with the Colorado Water Conservation Board.

This point dataset contains geologic information concerning regolith thickness and top-of-bedrock altitude at selected well and test-hole locations in the Lower Gunnison River Basin in Delta, Montrose, Ouray, and Gunnison Counties, Colorado. Regolith-thickness data were compiled from lithologic logs of wells and boreholes reported by the Colorado Division of Water Resources, U.S. Geological Survey, and Bureau of Reclamation. Bedrock-altitude values were computed from the bedrock altitude raster dataset (bralt). The U.S. Geological Survey prepared this dataset in cooperation with the Colorado Water Conservation Board.

This U.S. Geological Survey (USGS) data release contains stream water chemistry and streamflow data collected in late August and early September, 2021 from 28 sites located throughout Colorado, USA. The sampled streams all drain high-elevation mountain watersheds in areas where the bedrock is hydrothermally altered and contains abundant sulfide minerals. Most sampled streams are therefore affected by natural acid-rock drainage. All sites had been sampled in prior years so that the 2021 data could be used to evaluate potential changes in stream water chemistry in recent decades. Streamflow was also quantified at most sites using data from a sodium chloride slug addition wherein specific conductivity readings were used as a surrogate for the tracer concentration.

This U.S. Geological Survey (USGS) data release contains stream water chemistry and streamflow data collected in late August and early September, 2021 from 28 sites located throughout Colorado, USA. The sampled streams all drain high-elevation mountain watersheds in areas where the bedrock is hydrothermally altered and contains abundant sulfide minerals. Most sampled streams are therefore affected by natural acid-rock drainage. All sites had been sampled in prior years so that the 2021 data could be used to evaluate potential changes in stream water chemistry in recent decades. Streamflow was also quantified at most sites using data from a sodium chloride slug addition wherein specific conductivity readings were used as a surrogate for the tracer concentration.

These data were released prior to the October 1, 2016 effective date for the USGS’s policy dictating the review, approval, and release of scientific data as referenced in USGS Survey Manual Chapter 502.8 Fundamental Science Practices: Review and Approval of Scientific Data for Release. Note that this data release has been modified from its original version. This data release was originally published on the U.S. Geological Survey (USGS) Water Mission Area NSDI Node (Node) in 2008. The Node has since been deprecated, and the data release was revised and, in 2023, the files were moved over to Sciencebase, which is a USGS trusted digital repository. When this migration of files initially took place, each unit extent and surface file for the Mississippi embayment aquifer system was given its own landing page. The 2025 version of this data release revised the 2023 revision. This 2025 version regrouped the extents, surfaces, and metadata files, presenting them on one Sciencebase landing page. A new master metadata file was compiled to document all the datasets and each surface altitude raster is presented in three formats: ASCII, GRID, and TIFF (a new format). The 2025 version of the data release was created to make the spatial data more accessible to the user and to simplify the ScienceBase catalog. The following list of Digital Object Identifiers (DOI) are from the 2023 revision pages and have been deprecated and superseded by this data release's DOI (doi:10.5066/P1VRSZLE). Deprecated DOIs: doi:10.5066/P913ILLC, doi:10.5066/P9PV92DD, doi:10.5066/P99DN2Q7, doi:10.5066/P90OQTTN, doi:10.5066/P97M18BU, doi:10.5066/P9TKXK1S, doi:10.5066/P9PEIHPU, doi:10.5066/P97WO9AD, doi:10.5066/P95QSYP9, doi:10.5066/P9OX7ATU, doi:10.5066/P9MMLD4I, doi:10.5066/P9QIJ2UX, doi:10.5066/P96ERE0X, doi:10.5066/P9OMYUX4, doi:10.5066/P9C2AXIZ, doi:10.5066/P913AT6B, doi:10.5066/P9VJ7FHM, doi:10.5066/P95UZ2X7, doi:10.5066/P9JHYMO3 This data release provides outcrop and subcrop extents and digital surfaces containing the top altitude of the following hydrogeologic units in Arkansas, Alabama, Louisiana, Missouri, Mississippi, and Tennessee. The abbreviations used for each hydrogeologic unit is listed below. These abbreviations are used in names of the data release files. Extent file names end in "_extent" and the raster file names end in "_surf". 1. alvm - Mississippi River Valley Alluvial Aquifer (extent only) 2. vkbg - Vicksburg-Jackson Group 3. ucaq - Upper Claiborne aquifer 4. mccu - Middle Claiborne confining unit 5. mcaq - Middle Claiborne aquifer 6. lccu - Lower Claiborne confining unit 7. lcaq - Lower Claiborne aquifer 8. mwaq - Middle Wilcox aquifer 9. lwaq - Lower Wilcox aquifer 10. mdwy - Midway confining unit The hydrogeologic unit surface datasets contain 414 rows and 394 columns representing 1-mile grid spacing. In general, limitations of data interpolation included areas of sparse geophysical log control points, log datums not clearly defined for some logs, unknown exact extent of each hydrogeologic unit in subcrop, interpolation limitations, and values averaged over 1-mile grid spacing. This data release contains data sets that characterize the Mississippi embayment aquifer system. These data sets were assembled as part of the Mississippi Embayment Regional Aquifer Study (MERAS) as described in the associated report (Hart, R.M., Clark, B.R., and Bolyard, S.E., 2008, Digital surfaces and thicknesses of selected hydrogeologic units within the Mississippi Embayment Regional Aquifer Study (MERAS): U.S. Geological Survey Scientific Investigations Report 2008-5098, 33 p.) and utilized in the MERAS groundwater-flow model (Clark, B.R., and Hart, R.M., 2009, The Mississippi Embayment Regional Aquifer Study (MERAS): Documentation of a groundwater-flow model constructed to assess water availability in the Mississippi Embayment: U.S. Geological Survey Scientific Investigations Report 2009-5172, 61 p.) A supplementary shapefile containing the extent of the MERAS

Historical water and gas chemistry data from geothermal areas are important for detecting long-term patterns, informing geothermal energy exploration, development, and use, and for contextualizing more recent data. The U.S. Geological Survey has published water and gas chemistry data from geothermal areas in the western United States, which is primarily available as scanned PDF files. This makes the data difficult to access or include in large-scale data analysis. This data release provides digitized and reformatted data from 20 previously published U.S. Geological Survey Open-File reports and journal articles, representing 1867 water chemistry samples and 313 gas chemistry samples. All data have been standardized to the same units, geographic coordinates, and file format. Description of sample site location was improved. Many reports do not report geographic location coordinates; those that do are frequently inaccurate, as latitude and longitude were interpolated from a map, or in some cases, estimated in the field before the common use of global positioning systems (GPS). Collection dates for individual samples range from 1930 to 2005, although most samples were collected between the years 1970 and 2000. Samples are primarily from California, Oregon, and Washington, although some reports include data from sites in Montana, Idaho, Nevada, Utah, Arizona, and New Mexico. Attributes for both water and gas chemistry are: Sample name, Sample ID, Type, Collection date, Collection time, Reported location, Reported latitude, Reported longitude, Reported Easting, Reported Northing, Location description, Region, State, County, Latitude, Longitude, Location resolution, Location error, Elevation, Source, Author comment, and Digitizer comment. Attributes for water chemistry are: Well depth, Collection depth, Discharge, Temperature, pH (field), pH (lab), pH, Aluminum (Al), Arsenic (As), Boron (B), Barium (Ba), Bromide (Br), Calcium (Ca), Chloride (Cl), Carbonate (CO3), Alkalinity as carbonate (CO3), Cesium (Cs), Copper (Cu), Dissolved Organic Carbon as Carbon (DIC as C), Fluoride (F), Iron (Fe), Hydrogen sulfide (H2S), Bicarbonate (HCO3), Alkalinity as bicarbonate (HCO3), Carbonic acid (H2CO3), Mercury (Hg), Iodide (I), Potassium (K), Lithium (Li), Magnesium (Mg), Manganese (Mn), Molybdenum (Mo), total Nitrogen (N), Sodium (Na), Ammonium (NH4), Nickel (Ni), Nitrate (NO3), total Phosphorus (P), Lead (Pb), Phosphate (PO4), Rubidium (Rb), Silica (SiO2), Sulfate (SO4), Strontium (Sr), Uranium (U), Vanadium (V), Zinc (Zn), Reported cations, Reported anions, Cations, Anions, Reported total dissolved solids, Salinity, Charge balance, Specific conductance, isotopic composition of hydrogen (Delta 2H), isotopic composition of oxygen in water (Delta 18O (H2O)), Oxygen shift, isotopic composition of oxygen in sulfate (Delta 18O (SO4)), isotopic composition of carbon (Delta 13C), isotopic composition of carbon in dissolved inorganic carbon (Delta 13C (DIC)), Tritium (3H), and 14C. Attributes for gas chemistry are: Temperature, Total gas, argon (Ar), oxygen and argon (O2 + Ar), ethane (C2H6), methane (CH4), carbon dioxide (CO2), hydrogen (H2), hydrogen sulfide (H2S), helium (He), nitrogen (N2), ammonia (NH3), oxygen (O2), dissolved argon (Ar dissolved), dissolved methane (CH4 dissolved), dissolved carbon dioxide (CO2 dissolved), dissolved hydrogen (H2 dissolved), dissolved helium (He dissolved), dissolved nitrogen (N2 dissolved), dissolved ammonia (NH3 dissolved), dissolved oxygen (O2 dissolved), isotopic ratio of helium (3He/4He), isotopic ratio of helium corrected for the atmospheric isotopic composition of helium (3He/4He corrected), isotopic composition of nitrogen (Delta 15N), and isotopic composition of carbon in carbon dioxide (Delta 13C (CO2)).

Historical water and gas chemistry data from geothermal areas are important for detecting long-term patterns, informing geothermal energy exploration, development, and use, and for contextualizing more recent data. The U.S. Geological Survey has published water and gas chemistry data from geothermal areas in the western United States, which is primarily available as scanned PDF files. This makes the data difficult to access or include in large-scale data analysis. This data release provides digitized and reformatted data from 20 previously published U.S. Geological Survey Open-File reports and journal articles, representing 1867 water chemistry samples and 313 gas chemistry samples. All data have been standardized to the same units, geographic coordinates, and file format. Description of sample site location was improved. Many reports do not report geographic location coordinates; those that do are frequently inaccurate, as latitude and longitude were interpolated from a map, or in some cases, estimated in the field before the common use of global positioning systems (GPS). Collection dates for individual samples range from 1930 to 2005, although most samples were collected between the years 1970 and 2000. Samples are primarily from California, Oregon, and Washington, although some reports include data from sites in Montana, Idaho, Nevada, Utah, Arizona, and New Mexico. Attributes for both water and gas chemistry are: Sample name, Sample ID, Type, Collection date, Collection time, Reported location, Reported latitude, Reported longitude, Reported Easting, Reported Northing, Location description, Region, State, County, Latitude, Longitude, Location resolution, Location error, Elevation, Source, Author comment, and Digitizer comment. Attributes for water chemistry are: Well depth, Collection depth, Discharge, Temperature, pH (field), pH (lab), pH, Aluminum (Al), Arsenic (As), Boron (B), Barium (Ba), Bromide (Br), Calcium (Ca), Chloride (Cl), Carbonate (CO3), Alkalinity as carbonate (CO3), Cesium (Cs), Copper (Cu), Dissolved Organic Carbon as Carbon (DIC as C), Fluoride (F), Iron (Fe), Hydrogen sulfide (H2S), Bicarbonate (HCO3), Alkalinity as bicarbonate (HCO3), Carbonic acid (H2CO3), Mercury (Hg), Iodide (I), Potassium (K), Lithium (Li), Magnesium (Mg), Manganese (Mn), Molybdenum (Mo), total Nitrogen (N), Sodium (Na), Ammonium (NH4), Nickel (Ni), Nitrate (NO3), total Phosphorus (P), Lead (Pb), Phosphate (PO4), Rubidium (Rb), Silica (SiO2), Sulfate (SO4), Strontium (Sr), Uranium (U), Vanadium (V), Zinc (Zn), Reported cations, Reported anions, Cations, Anions, Reported total dissolved solids, Salinity, Charge balance, Specific conductance, isotopic composition of hydrogen (Delta 2H), isotopic composition of oxygen in water (Delta 18O (H2O)), Oxygen shift, isotopic composition of oxygen in sulfate (Delta 18O (SO4)), isotopic composition of carbon (Delta 13C), isotopic composition of carbon in dissolved inorganic carbon (Delta 13C (DIC)), Tritium (3H), and 14C. Attributes for gas chemistry are: Temperature, Total gas, argon (Ar), oxygen and argon (O2 + Ar), ethane (C2H6), methane (CH4), carbon dioxide (CO2), hydrogen (H2), hydrogen sulfide (H2S), helium (He), nitrogen (N2), ammonia (NH3), oxygen (O2), dissolved argon (Ar dissolved), dissolved methane (CH4 dissolved), dissolved carbon dioxide (CO2 dissolved), dissolved hydrogen (H2 dissolved), dissolved helium (He dissolved), dissolved nitrogen (N2 dissolved), dissolved ammonia (NH3 dissolved), dissolved oxygen (O2 dissolved), isotopic ratio of helium (3He/4He), isotopic ratio of helium corrected for the atmospheric isotopic composition of helium (3He/4He corrected), isotopic composition of nitrogen (Delta 15N), and isotopic composition of carbon in carbon dioxide (Delta 13C (CO2)).