Surface water, springs and wells in Pinnacles National Park (San Benito and Monterey Counties, CA) were sampled in the Fall of 2016 and Spring of 2017. Field parameters such as in situ pH, TDS/conductivity, and temperature were assessed. GPS coordinates for all samples were taken. Comprehensive groundwater chemistry, including major and minor elements, alkalinity, nutrients (and other parameters), Sr isotopes and REE concentrations, was analyzed at the National Water Quality Lab, USGS, Denver CO; and in USGS labs in Menlo Park, CA. One field visit on 8/20/2017 was made to obtain rock samples from the volcanic and sedimentary rocks in and around the park, which were digested and analyzed for whole rock chemistry (XRF, OES, ICP MS) by the Analytical Chemistry Lab (Mineral Resources Program, USGS, Denver CO). Sr isotopes for these samples were analyzed in the Menlo Park Metal Isotope Lab at the USGS. Precipitation was collected in a bulk collector during the winter of 2016-2017 and the chemistry and Sr isotopes of bulk samples was analyzed by ICP-MS or TIMS at the USGS Metal Isotope Lab in Menlo Park, CA.

There are over 10,000 hydrothermal features in Yellowstone National Park (YNP), where waters have pH values ranging from about 1 to 10 and surface temperatures up to 95 °C. Active hydrothermal areas in YNP provide insight into a variety of processes occurring at depth, such as water-rock and oxidation-reduction (redox) reactions, the formation of alteration minerals, and microbial (thermophile) metabolism in extreme environments, and possible indications of volcanic unrest. Investigations into the water chemistry of hydrothermal features, streams, and rivers in YNP have been conducted by the U.S. Geological Survey (USGS) and other earth-science organizations and academic institutions since 1883 (Gooch and Whitfield, 1888; Price and others, 2024). More recently, USGS researchers have sampled hydrothermal features in YNP at least annually since 1994 (McCleskey and others, 2014, and references within). In this Data Release, the chemical and isotopic analyses of 845 water samples collected beginning in 2009 are reported for numerous thermal and non-thermal features in YNP. This report combines water chemistry data presented in McCleskey and others (2014) with data collected after 2014. These water samples were collected and analyzed as part of research investigations in YNP on and as part of the Yellowstone Volcano Observatory monitoring plans (Yellowstone Volcano Observatory, 2006); arsenic, iron, nitrogen, and sulfur redox species in hot springs and overflow drainages; the occurrence and distribution of dissolved mercury and arsenic; and general hydrogeochemistry of hot springs throughout YNP. For most samples, data includes water temperature, pH, specific conductance, dissolved oxygen, and concentrations of major cations, anions, trace metals, alkalinity, sulfur redox species (hydrogen sulfide and thiosulfate), nutrients, silica, boron, arsenic and iron redox species, acidity, dissolved organic carbon, and hydrogen and oxygen isotope ratios. For select samples, tritium (3H), stable carbon isotopes of the dissolved inorganic carbon, and sulfur isotopes of sulfate are presented. In addition, chemical data for river, stream, and lake waters were obtained to determine input of different solutes from thermal areas throughout YNP. References Cited Gooch, F.A., and Whitfield, J.E., 1888, Analyses of waters of the Yellowstone National Park with an account of the methods of analysis employed: Bulletin 47, p. 84. McCleskey, R.B., Chiu, R.B., Nordstrom, D.K., Campbell, K.M., Roth, D.A., Ball, J.W., and Plowman, T.I., 2014, Water-Chemistry Data for Selected Springs, Geysers, and Streams in Yellowstone National Park, Wyoming, Beginning 2009: doi:10.5066/F7M043FS. Price, M.B., McCleskey, R.B., Oaks, A., Hurwitz, S., and Nordstrom, D.K., 2024, Historic Water Chemistry Data for Thermal Features, Streams, and Rivers in the Yellowstone National Park Area, 1883-2021: U.S. Geological Survey data release, https://doi.org/10.5066/P9KSEVI1. Yellowstone Volcano Observatory, 2006, Volcano and earthquake monitoring plan for the Yellowstone Volcano Observatory, 2006-2015: U.S. Geological Survey Scientific Investigations Report 2006-5276, http://pubs.usgs.gov/sir/2006/5276/. First posted - September 19, 2022 (available from author) Revised - March 4, 2025 (version 2.0) NOTE: While previous versions are available from the author, all the records in previous versions can be found in version 2.0.

There are over 10,000 hydrothermal features in Yellowstone National Park (YNP), where waters have pH values ranging from about 1 to 10 and surface temperatures up to 95 °C. Active hydrothermal areas in YNP provide insight into a variety of processes occurring at depth, such as water-rock and oxidation-reduction (redox) reactions, the formation of alteration minerals, and microbial (thermophile) metabolism in extreme environments, and possible indications of volcanic unrest. Investigations into the water chemistry of hydrothermal features, streams, and rivers in YNP have been conducted by the U.S. Geological Survey (USGS) and other earth-science organizations and academic institutions since 1883 (Gooch and Whitfield, 1888; Price and others, 2024). More recently, USGS researchers have sampled hydrothermal features in YNP at least annually since 1994 (McCleskey and others, 2014, and references within). In this Data Release, the chemical and isotopic analyses of 845 water samples collected beginning in 2009 are reported for numerous thermal and non-thermal features in YNP. This report combines water chemistry data presented in McCleskey and others (2014) with data collected after 2014. These water samples were collected and analyzed as part of research investigations in YNP on and as part of the Yellowstone Volcano Observatory monitoring plans (Yellowstone Volcano Observatory, 2006); arsenic, iron, nitrogen, and sulfur redox species in hot springs and overflow drainages; the occurrence and distribution of dissolved mercury and arsenic; and general hydrogeochemistry of hot springs throughout YNP. For most samples, data includes water temperature, pH, specific conductance, dissolved oxygen, and concentrations of major cations, anions, trace metals, alkalinity, sulfur redox species (hydrogen sulfide and thiosulfate), nutrients, silica, boron, arsenic and iron redox species, acidity, dissolved organic carbon, and hydrogen and oxygen isotope ratios. For select samples, tritium (3H), stable carbon isotopes of the dissolved inorganic carbon, and sulfur isotopes of sulfate are presented. In addition, chemical data for river, stream, and lake waters were obtained to determine input of different solutes from thermal areas throughout YNP. References Cited Gooch, F.A., and Whitfield, J.E., 1888, Analyses of waters of the Yellowstone National Park with an account of the methods of analysis employed: Bulletin 47, p. 84. McCleskey, R.B., Chiu, R.B., Nordstrom, D.K., Campbell, K.M., Roth, D.A., Ball, J.W., and Plowman, T.I., 2014, Water-Chemistry Data for Selected Springs, Geysers, and Streams in Yellowstone National Park, Wyoming, Beginning 2009: doi:10.5066/F7M043FS. Price, M.B., McCleskey, R.B., Oaks, A., Hurwitz, S., and Nordstrom, D.K., 2024, Historic Water Chemistry Data for Thermal Features, Streams, and Rivers in the Yellowstone National Park Area, 1883-2021: U.S. Geological Survey data release, https://doi.org/10.5066/P9KSEVI1. Yellowstone Volcano Observatory, 2006, Volcano and earthquake monitoring plan for the Yellowstone Volcano Observatory, 2006-2015: U.S. Geological Survey Scientific Investigations Report 2006-5276, http://pubs.usgs.gov/sir/2006/5276/. First posted - September 19, 2022 (available from author) Revised - March 4, 2025 (version 2.0) NOTE: While previous versions are available from the author, all the records in previous versions can be found in version 2.0.

Water and gas chemistry data from: Mariner, R.H., Presser, T.S. and Evans, W.C., 1976. Chemical characteristics of the major thermal springs of Montana. U.S. Geological Survey Open-File Report 76-480, 38p., https://doi.org/10.3133/ofr76480. Water chemistry data was digitized for 33 samples. Reported attributes include: Sample name, Type, Collection date, Reported location, Location description, State, County, Latitude, Longitude, Location resolution, Location error, Temperature, pH (field), Aluminum (Al), Boron (B), Calcium (Ca), Chloride (Cl), Fluoride (F), Hydrogen sulfide (H2S), Alkalinity as bicarbonate (HCO3), Potassium (K), Lithium (Li), Magnesium (Mg), Manganese (Mn), Sodium (Na), Ammonium (NH4), Rubidium (Rb), Silica (SiO2), Sulfate (SO4), Zinc (Zn), Cations, Anions, Reported total dissolved solids, Salinity, Charge balance, Specific conductance, Isotopic composition of hydrogen (Delta 2H), Isotopic composition of oxygen (Delta 18O H2O), Oxygen shift, Author comment, Digitizer comment. Gas chemistry data was digitized for 8 samples. Reported attributes include: Sample name, Type, Collection date, State, County, Latitude, Longitude, Location resolution, Location error, Temperature, Total gas, Oxygen and argon (O2 + Ar), Methane (CH4), Carbon dioxide (CO2), Nitrogen (N2), Author comment, Digitizer comment. Data was digitized from Tables 1, 2, 3, 4, 6, 9, and 10. The following tables were not digitized: Table 5: molal ratios of chemical compositions of thermal samples. Table 7: free energy for reaction states of 5 minerals for thermal samples. Table 8: estimated aquifer temperatures.

Water and gas chemistry data from: Mariner, R.H., Presser, T.S. and Evans, W.C., 1976. Chemical characteristics of the major thermal springs of Montana. U.S. Geological Survey Open-File Report 76-480, 38p., https://doi.org/10.3133/ofr76480. Water chemistry data was digitized for 33 samples. Reported attributes include: Sample name, Type, Collection date, Reported location, Location description, State, County, Latitude, Longitude, Location resolution, Location error, Temperature, pH (field), Aluminum (Al), Boron (B), Calcium (Ca), Chloride (Cl), Fluoride (F), Hydrogen sulfide (H2S), Alkalinity as bicarbonate (HCO3), Potassium (K), Lithium (Li), Magnesium (Mg), Manganese (Mn), Sodium (Na), Ammonium (NH4), Rubidium (Rb), Silica (SiO2), Sulfate (SO4), Zinc (Zn), Cations, Anions, Reported total dissolved solids, Salinity, Charge balance, Specific conductance, Isotopic composition of hydrogen (Delta 2H), Isotopic composition of oxygen (Delta 18O H2O), Oxygen shift, Author comment, Digitizer comment. Gas chemistry data was digitized for 8 samples. Reported attributes include: Sample name, Type, Collection date, State, County, Latitude, Longitude, Location resolution, Location error, Temperature, Total gas, Oxygen and argon (O2 + Ar), Methane (CH4), Carbon dioxide (CO2), Nitrogen (N2), Author comment, Digitizer comment. Data was digitized from Tables 1, 2, 3, 4, 6, 9, and 10. The following tables were not digitized: Table 5: molal ratios of chemical compositions of thermal samples. Table 7: free energy for reaction states of 5 minerals for thermal samples. Table 8: estimated aquifer temperatures.

This data release contains whole-rock major, minor, and trace element geochemical data for carbonatite samples from the Mountain Pass rare earth element (REE) deposit located in southeastern California. The Mountain Pass deposit is the largest REE deposit in the United States and in 2021, produced 43,000 metric tons (expressed as rare-earth-oxide equivalent; U.S. Geological Survey, 2022). Samples include a suite of outcrop samples (2018) and a suite of composite samples (2019). Data are reported in comma-separated values (CSV) files. All column headings and abbreviations are explained in the metadata. Reference U.S. Geological Survey, 2022, Mineral commodity summaries 2022: U.S. Geological Survey, 202 p., https://doi.org/10.3133/mcs2022.

This data release contains whole-rock major, minor, and trace element geochemical data for carbonatite samples from the Mountain Pass rare earth element (REE) deposit located in southeastern California. The Mountain Pass deposit is the largest REE deposit in the United States and in 2021, produced 43,000 metric tons (expressed as rare-earth-oxide equivalent; U.S. Geological Survey, 2022). Samples include a suite of outcrop samples (2018) and a suite of composite samples (2019). Data are reported in comma-separated values (CSV) files. All column headings and abbreviations are explained in the metadata. Reference U.S. Geological Survey, 2022, Mineral commodity summaries 2022: U.S. Geological Survey, 202 p., https://doi.org/10.3133/mcs2022.

Water and gas chemistry data from: Mariner, R.H., Presser, T.S. and Evans, W.C., 1977. Hot springs of the central Sierra Nevada, California: U.S. Geological Survey Open-File Report 77-559, 37 p., https://doi.org/10.3133/ofr77559. Water chemistry data was digitized for 21 samples. Reported attributes include: Sample name, Type, Reported location, Location description, State, County, Latitude, Longitude, Location resolution, Location error, Temperature, pH (field), Aluminum (Al), Boron (B), Calcium (Ca), Chloride (Cl), Cesium (Cs), Copper (Cu), Fluoride (F), Iron (Fe), Hydrogen sulfide (H2S), Bicarbonate (HCO3), Alkalinity as bicarbonate (HCO3), Mercury (Hg), Potassium (K), Lithium (Li), Magnesium (Mg), Manganese (Mn), Sodium (Na), Ammonium (NH4), Nickel (Ni), Rubidium (Rb), Silica (SiO2), Sulfate (SO4), Zinc (Zn), Cations, Anions, Reported total dissolved solids, Salinity, Charge balance, Isotopic composition of hydrogen (Delta 2H), Isotopic composition of oxygen in water (Delta 18O H2O), Oxygen shift, Digitizer comment. Gas chemistry data was digitized for 12 samples. Reported attributes include: Sample name, Type, State, County, Latitude, Longitude, Location resolution, Location error, Total gas, Oxygen and argon (O2 + Ar), Ethane (C2H6), Methane (CH4), Carbon dioxide (CO2), Nitrogen (N2), Author comment, Digitizer comment. Data was digitized from Tables 1, 3, 4, 5, 7, 9, and 10. The following tables were not digitized: Table 2: age and lithology of the bedrock at each thermal spring. Table 6: the mole ratios of major to minor constituents of thermal springs. Table 8: the equilibrium states of reactions in the thermal springs. Table 11: measured temperatures and estimated reservoir temperatures for the thermal springs.

Water and gas chemistry data from: Mariner, R.H., Presser, T.S. and Evans, W.C., 1977. Hot springs of the central Sierra Nevada, California: U.S. Geological Survey Open-File Report 77-559, 37 p., https://doi.org/10.3133/ofr77559. Water chemistry data was digitized for 21 samples. Reported attributes include: Sample name, Type, Reported location, Location description, State, County, Latitude, Longitude, Location resolution, Location error, Temperature, pH (field), Aluminum (Al), Boron (B), Calcium (Ca), Chloride (Cl), Cesium (Cs), Copper (Cu), Fluoride (F), Iron (Fe), Hydrogen sulfide (H2S), Bicarbonate (HCO3), Alkalinity as bicarbonate (HCO3), Mercury (Hg), Potassium (K), Lithium (Li), Magnesium (Mg), Manganese (Mn), Sodium (Na), Ammonium (NH4), Nickel (Ni), Rubidium (Rb), Silica (SiO2), Sulfate (SO4), Zinc (Zn), Cations, Anions, Reported total dissolved solids, Salinity, Charge balance, Isotopic composition of hydrogen (Delta 2H), Isotopic composition of oxygen in water (Delta 18O H2O), Oxygen shift, Digitizer comment. Gas chemistry data was digitized for 12 samples. Reported attributes include: Sample name, Type, State, County, Latitude, Longitude, Location resolution, Location error, Total gas, Oxygen and argon (O2 + Ar), Ethane (C2H6), Methane (CH4), Carbon dioxide (CO2), Nitrogen (N2), Author comment, Digitizer comment. Data was digitized from Tables 1, 3, 4, 5, 7, 9, and 10. The following tables were not digitized: Table 2: age and lithology of the bedrock at each thermal spring. Table 6: the mole ratios of major to minor constituents of thermal springs. Table 8: the equilibrium states of reactions in the thermal springs. Table 11: measured temperatures and estimated reservoir temperatures for the thermal springs.

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.