This data release documents three Microsoft Excel tables that contain data for understanding environmental tracer concentrations in groundwater of the High Plains aquifer system. Results of dissolved-gas modeling using environmental tracer concentrations (tritium, tritiogenic helium-3, and radiogenic helium-4), for the sample network (VPFS, vertical flow path study) are described. Dissolved gas modeling results (ModOut) contains detailed information on the calibration of dissolved gas models to measured dissolved-gas concentrations (neon, argon, krypton, xenon, and nitrogen). Calibration was done using methods described by Aeschbach-Hertig and others (1999 & 2000) with modifications to include nitrogen gas (Weiss, 1970). In most cases, a single set of noble-gas concentrations (neon, argon, krypton, and xenon) was used to solve for recharge conditions (recharge temperature, excess or entrapped air, and fractionation) using the unfractionated excess air (UA) and closed equilibration (CE) models (Aeschbach-Hertig and others, 1999 & 2000). In cases where noble gas data were not available, multiple analyses of nitrogen and argon (collected sequentially on the same sample date) were used to solve for recharge conditions. Environmental tracer results (TrcOut) contains detailed information on calculations of environmental tracer data. Dissolved gas models were paired with measured helium isotope ratios (3He/4He) and helium concentrations to calculate concentrations of tritiogenic helium-3 (the component of 3He derived from tritium decay; Solomon and Cook, 2000) and radiogenic helium-4 (the component of 4He derived from the decay of uranium and thorium in aquifer materials; Solomon, 2000). Tracer concentrations were computed for each combination of measure dissolved gas concentrations when sites had multiple measured gas results and analyses for helium isotopes. Average environmental tracer results (AvgTrcOut) contains average tracer concentrations for a given site used for determination of groundwater ages. Aeschbach-Hertig, W., F. Peeters, U. Beyerle, and R. Kipfer (1999), Interpretation of dissolved atmospheric noble gases in natural waters, Water Resour. Res., 35(9), 2779–2792,https://dx.doi.org/10.1029/1999WR900130. Aeschbach-Hertig, W., F. Peeters, U. Beyerle, and R. Kipfer (2000), Paleotemperature reconstruction from noble gases in ground water taking into account equilibration with entrapped air, Nature, v. 405, Iss. 6790, pg. 1040-1044, http://dx.doi.org/10.1038/35016542 Solomon, D.K., and P.G. Cook. 2000. 3H and 3He. In Environmental Tracers in Subsurface Hydrology, ed. P.G. Cook and A.L. Herczeg, 197-424. Boston: Kluwer Academic Publishers. Solomon, D.K. 2000. 4He in groundwater. In Environmental Tracers in Subsurface Hydrology, ed. P.G. Cook and A.L. Herczeg, 425-439. Boston: Kluwer Academic Publishers. Weiss, R. F., 1970, The solubility of nitrogen, oxygen, and argon in water and seawater, Deep Sea Research, vol. 17, pp. 721-735, https://doi.org/10.1016/0011-7471(70)90037-9.

This data release documents three Microsoft Excel tables that contain data for understanding environmental tracer concentrations in groundwater of the Columbia Plateau aquifer system. Results of dissolved-gas modeling using environmental tracer concentrations (tritium, tritiogenic helium-3, and radiogenic helium-4), for the sample network (VPFS, vertical flow path study) are described. Dissolved gas modeling results (ModOut) contains detailed information on the calibration of dissolved gas models to measured dissolved-gas concentrations (neon, argon, krypton, xenon, and nitrogen). Calibration was done using methods described by Aeschbach-Hertig and others (1999 & 2000) with modifications to include nitrogen gas (Weiss, 1970). In most cases, a single set of noble-gas concentrations (neon, argon, krypton, and xenon) was used to solve for recharge conditions (recharge temperature, excess or entrapped air, and fractionation) using the unfractionated excess air (UA) and closed equilibration (CE) models (Aeschbach-Hertig and others, 1999 & 2000). In cases where noble gas data were not available, multiple analyses of nitrogen and argon (collected sequentially on the same sample date) were used to solve for recharge conditions. Environmental tracer results (TrcOut) contains detailed information on calculations of environmental tracer data. Dissolved gas models were paired with measured helium isotope ratios (3He/4He) and helium concentrations to calculate concentrations of tritiogenic helium-3 (the component of 3He derived from tritium decay; Solomon and Cook, 2000) and radiogenic helium-4 (the component of 4He derived from the decay of uranium and thorium in aquifer materials; Solomon, 2000). Tracer concentrations were computed for each combination of measure dissolved gas concentrations when sites had multiple measured gas results and analyses for helium isotopes. Average environmental tracer results (AvgTrcOut) contains average tracer concentrations for a given site used for determination of groundwater ages. Aeschbach-Hertig, W., F. Peeters, U. Beyerle, and R. Kipfer (1999), Interpretation of dissolved atmospheric noble gases in natural waters, Water Resour. Res., 35(9), 2779–2792,https://dx.doi.org/10.1029/1999WR900130. Aeschbach-Hertig, W., F. Peeters, U. Beyerle, and R. Kipfer (2000), Paleotemperature reconstruction from noble gases in ground water taking into account equilibration with entrapped air, Nature, v. 405, Iss. 6790, pg. 1040-1044, http://dx.doi.org/10.1038/35016542 Solomon, D.K., and P.G. Cook. 2000. 3H and 3He. In Environmental Tracers in Subsurface Hydrology, ed. P.G. Cook and A.L. Herczeg, 197-424. Boston: Kluwer Academic Publishers. Solomon, D.K. 2000. 4He in groundwater. In Environmental Tracers in Subsurface Hydrology, ed. P.G. Cook and A.L. Herczeg, 425-439. Boston: Kluwer Academic Publishers. Weiss, R. F., 1970, The solubility of nitrogen, oxygen, and argon in water and seawater, Deep Sea Research, vol. 17, pp. 721-735, https://doi.org/10.1016/0011-7471(70)90037-9.

This data release documents 155 sets of dissolved noble gas analyses (neon, argon, krypton, xenon) and 153 modeled recharge temperatures for groundwater sampled from domestic water supply wells and springs throughout the northern Sierra Nevada foothills as part of the California State Water Resources Control Board’s Groundwater Ambient Monitoring and Assessment (GAMA) Program in 2015-2017. Data from two of the U.S. Geological Survey’s Priority Basin Project Shallow Aquifer Assessment study units are presented here: The Yuba and Bear Watersheds (YB) Shallow Aquifer Study Unit (sampled in 2015-2016) and the Mokelumne, Cosumnes, and American River Watersheds (MCAW) Shallow Aquifer Study Unit (sampled in 2016-2017). The YB and MCAW study units include domestic well and spring sites within watersheds overlying fractured rock aquifer systems of the Sierra Nevada hydrogeologic province of California in Nevada, Yuba, Sierra, Placer, El Dorado, Amador, and Calaveras Counties. Study design and site attributes for the YB and MCAW study units are presented by Jasper and others (2017) and Shelton and others (2018), respectively. This data release contains one tab-delimited text file containing Table 1, which reports the results of dissolved noble gas analyses for environmental samples from 72 sites in the YB study unit in addition to eight field replicates (80 samples total) and environmental samples from 67 sites in the MCAW study unit in addition to eight field replicates (75 samples total). Table 1 also contains groundwater recharge temperatures for 153 samples that were modeled using measured dissolved noble gas concentrations, land surface elevation at the sample site, and sample salinity. Model inputs and outputs including Monte Carlo simulations to estimate model parameter errors are also included in Table 1. Detailed descriptions for Table 1 column fields are provided in an additional tab-delimited text file of Table 1 column definitions. Abbreviations used in this data release are explained in an additional tab-delimited text file of abbreviations. These data support the following publications: Jasper, M., Bennett, G.L., and Fram, M.S., 2017, Groundwater-Quality Data in the Yuba and Bear Watersheds Shallow Aquifer Study Unit, 2015-2016: Results from the California GAMA Priority Basin Project: U.S. Geological Survey data release, https://doi.org/10.5066/F73F4MS9. Levy, Z.F., Fram, M.S., Faulkner, K.E., Alpers, C.N., Soltero, E.M., and Taylor, K.A., 2020, Effects of montane watershed development on vulnerability of domestic groundwater supply during drought: Journal of Hydrology, v. 583, https://doi.org/10.1016/j.jhydrol.2020.124567. Shelton, J.L., Fram, M.S., Goldrath, D.A., Bennett, G.L., V, and Jasper, M., 2018, Groundwater-quality data in the Mokelumne, Cosumnes, and American River Watersheds Shallow Aquifer Study Unit, 2016-2017: Results from the California GAMA Priority Basin Project: U.S. Geological Survey data release, https://doi.org/10.5066/F78G8JXP.

This data release documents nine Microsoft Excel tables that contain data for understanding groundwater ages in the Glacial aquifer system. Results for the four sample networks (PAS, principal aquifer study; MSS, modeling support study; FPS, flow path study) are described by three tables each: dissolved gas modeling results, environmental tracer concentrations (tritium, tritiogenic helium-3, sulfur hexafluoride, carbon-14, and radiogenic helium-4), and results for the mean age and age distribution. Tables are labeled by network and data type (as described below) separated by an underscore (_). For example, dissolved gas modeling results from the PAS network is label ‘PAS_NGmodel’. Dissolved gas modeling results (NGmodel) contains detailed information on the calibration of dissolved gas models to dissolved gas concentrations (neon, argon, krypton, xenon, and nitrogen). Calibration was done using methods described by Aeschbach-Hertig and others (1999) with modifications to include nitrogen gas (Weiss 1970). In most cases, a single set of noble gas data (neon, argon, krypton, and xenon) were used to determine recharge conditions (recharge temperature, excess air or entrapped air, fractionation). In cases where noble gas data were not available, multiple analyses of nitrogen and argon (collected sequentially on the same sample date) were used to determine recharge conditions. Environmental tracer results (Tracers) contain detailed information on calculations of environmental tracer data. Dissolved gas models were paired with sulfur hexafluoride and helium isotopes (3He/4He) and helium to determine concentrations of tritiogenic helium-3 (from decay of tritium; Solomon and Cook, 2000) and radiogenic helium-4 (from decay of uranium and thorium in aquifer materials; Solomon, 2000). Multiple tracer concentrations were computed when sites had multiple dissolved gas model results and analyses for sulfur hexafluoride or helium isotopes. Mean age and age distribution results (LPMModOut) contain final models of groundwater age by calibration of lumped parameter models to tracer concentrations (Jurgens and others, 2012). One additional table describes LPM results from a previous sampling of the FPS network in 2004. Tracer concentrations from 2004 FPS sampling are described in previous publication (Tesoriero et al., 2007; Saad, 2008). Dissolved gas modeling and environmental tracer results were averaged when multiple dissolved gas models and tracer concentrations were computed. In cases where age was modeled with a binary lumped parameter model (BMM), the mean age was computed from the mean age and fraction of the two components in the mixture. Please see the processing steps below and the main manuscript for additional details on the results presented in this table.

This data release documents nine Microsoft Excel tables that contain data for understanding groundwater ages in the Glacial aquifer system. Results for the four sample networks (PAS, principal aquifer study; MSS, modeling support study; FPS, flow path study) are described by three tables each: dissolved gas modeling results, environmental tracer concentrations (tritium, tritiogenic helium-3, sulfur hexafluoride, carbon-14, and radiogenic helium-4), and results for the mean age and age distribution. Tables are labeled by network and data type (as described below) separated by an underscore (_). For example, dissolved gas modeling results from the PAS network is label ‘PAS_NGmodel’. Dissolved gas modeling results (NGmodel) contains detailed information on the calibration of dissolved gas models to dissolved gas concentrations (neon, argon, krypton, xenon, and nitrogen). Calibration was done using methods described by Aeschbach-Hertig and others (1999) with modifications to include nitrogen gas (Weiss 1970). In most cases, a single set of noble gas data (neon, argon, krypton, and xenon) were used to determine recharge conditions (recharge temperature, excess air or entrapped air, fractionation). In cases where noble gas data were not available, multiple analyses of nitrogen and argon (collected sequentially on the same sample date) were used to determine recharge conditions. Environmental tracer results (Tracers) contain detailed information on calculations of environmental tracer data. Dissolved gas models were paired with sulfur hexafluoride and helium isotopes (3He/4He) and helium to determine concentrations of tritiogenic helium-3 (from decay of tritium; Solomon and Cook, 2000) and radiogenic helium-4 (from decay of uranium and thorium in aquifer materials; Solomon, 2000). Multiple tracer concentrations were computed when sites had multiple dissolved gas model results and analyses for sulfur hexafluoride or helium isotopes. Mean age and age distribution results (LPMModOut) contain final models of groundwater age by calibration of lumped parameter models to tracer concentrations (Jurgens and others, 2012). One additional table describes LPM results from a previous sampling of the FPS network in 2004. Tracer concentrations from 2004 FPS sampling are described in previous publication (Tesoriero et al., 2007; Saad, 2008). Dissolved gas modeling and environmental tracer results were averaged when multiple dissolved gas models and tracer concentrations were computed. In cases where age was modeled with a binary lumped parameter model (BMM), the mean age was computed from the mean age and fraction of the two components in the mixture. Please see the processing steps below and the main manuscript for additional details on the results presented in this table.

This dataset contains measurements of dissolved hydrocarbons in from various water sources, as well as ancillary raw calibration data showing the stability of the gas chromatograph with an atomic emission detector and flame ionization detector (GC-AED-FID) analytical system over time. Across multiple studies, samples from tap water, groundwater, surface water, springs, mine outflows, and blank materials were analyzed using this system over a period from 2014 to 2017, comprising 172 samples analyzed. In addition to water samples, 183 calibrations conducted over the same period of time are included to document the stability of the GC-AED-FID system over time. The target analytes in this study were: methane (CH4), ethane (C2H6), ethene (C2H4), ethyne (C2H2), propane (C3H8), propene (C3H6), i-butane (C4H10), n-butane (C4H10), 1-butene (C4H8), propyne (C3H4), i-pentane (C5H12), n-pentane (C5H12), 2-methyl-pentane (C6H14), 3-methyl-pentane (C6H14), hexane (C6H14), and benzene (C6H6).

This dataset contains measurements of dissolved hydrocarbons in from various water sources, as well as ancillary raw calibration data showing the stability of the gas chromatograph with an atomic emission detector and flame ionization detector (GC-AED-FID) analytical system over time. Across multiple studies, samples from tap water, groundwater, surface water, springs, mine outflows, and blank materials were analyzed using this system over a period from 2014 to 2017, comprising 172 samples analyzed. In addition to water samples, 183 calibrations conducted over the same period of time are included to document the stability of the GC-AED-FID system over time. The target analytes in this study were: methane (CH4), ethane (C2H6), ethene (C2H4), ethyne (C2H2), propane (C3H8), propene (C3H6), i-butane (C4H10), n-butane (C4H10), 1-butene (C4H8), propyne (C3H4), i-pentane (C5H12), n-pentane (C5H12), 2-methyl-pentane (C6H14), 3-methyl-pentane (C6H14), hexane (C6H14), and benzene (C6H6).

Dissolved noble gas data were collected using a portable mass spectrometer mounted on inflatable rafts on the Colorado River near Glenwood Springs, Colorado and the Virgin River near La Verkin, Utah. Data were collected approximately every 3 to 10 minutes for a suite of noble gases including helium (He), neon (Ne), argon (Ar), krypton (Kr), and xenon (Xe). Patterns in observed dissolved He concentrations were used to locate diffuse discharge of saline geothermal water, which commonly have elevated He concentrations. Diffuse groundwater discharge can be difficult to locate and quantify, and the dissolved He signals are a novel approach to understanding diffuse geothermal discharge to rivers. Dissolved He data were also used in a mass balance model to estimate the quantity of discharging groundwater.

Dissolved noble gas data were collected using a portable mass spectrometer mounted on inflatable rafts on the Colorado River near Glenwood Springs, Colorado and the Virgin River near La Verkin, Utah. Data were collected approximately every 3 to 10 minutes for a suite of noble gases including helium (He), neon (Ne), argon (Ar), krypton (Kr), and xenon (Xe). Patterns in observed dissolved He concentrations were used to locate diffuse discharge of saline geothermal water, which commonly have elevated He concentrations. Diffuse groundwater discharge can be difficult to locate and quantify, and the dissolved He signals are a novel approach to understanding diffuse geothermal discharge to rivers. Dissolved He data were also used in a mass balance model to estimate the quantity of discharging groundwater.

This data release contains geochemical and mineralogical laboratory results from core samples collected from the USGS Cow Creek 1-21 well. The well was drilled and cored in 2022 and targeted the Lewis Shale on the eastern edge of the Washakie Basin in Carbon County, Wyoming. The core data include results from total organic carbon (TOC) and total carbon (TC) analysis, programmed pyrolysis, inductively coupled plasma-optical emission spectroscopy and mass spectrometry (ICP-OES/MS), X-ray diffraction (XRD), stable isotope (C-13) analysis, and vitrinite reflectance analysis. A separate data release contains 4 geophysical wire line logs and is available at .