The datasets contained herein were collected as part of a cooperative U.S. Geological Survey (USGS) and U.S. Environmental Protection Agency (EPA) project entitled "Field Investigations to Help Support the Assessment of Background Concentrations for Uranium at the Homestake Mining Company, Superfund Site near Milan, New Mexico, July 2016." Groundwater samples were collected from pre-selected wells and analyzed for metals (including uranium), alkalinity, ammonia, common ions, nitrogen, gross alpha/beta, radium isotopes, Radon-22, uranium isotopes, stable isotopes, sulfur isotopes, nitrogen isotopes, helium-4, dissolved gases, tritium/helium-3, carbon-14 and chlorofluorocarbons. Groundwater samples were collected using micropurge, volumetric, and passive samplers. Seven different laboratories analyzed the samples; separate datasets containing the results from each laboratory are provided in this data release. Microsoft excel .xlsx, xml, and tab-delimited text files are included for most dataset. A subset of the files are in .csv format.

The datasets contained herein were collected as part of a cooperative U.S. Geological Survey (USGS) and U.S. Environmental Protection Agency (EPA) project entitled "Field Investigations to Help Support the Assessment of Background Concentrations for Uranium at the Homestake Mining Company, Superfund Site near Milan, New Mexico, July 2016." Groundwater samples were collected from pre-selected wells and analyzed for metals (including uranium), alkalinity, ammonia, common ions, nitrogen, gross alpha/beta, radium isotopes, Radon-22, uranium isotopes, stable isotopes, sulfur isotopes, nitrogen isotopes, helium-4, dissolved gases, tritium/helium-3, carbon-14 and chlorofluorocarbons. Groundwater samples were collected using micropurge, volumetric, and passive samplers. Seven different laboratories analyzed the samples; separate datasets containing the results from each laboratory are provided in this data release. Microsoft excel .xlsx, xml, and tab-delimited text files are included for most dataset. A subset of the files are in .csv format.

The datasets contained herein were collected as part of a cooperative U.S. Geological Survey (USGS) and U.S. Environmental Protection Agency (EPA) project entitled "Field Investigations to Help Support the Assessment of Background Concentrations for Uranium at the Homestake Mining Company, Superfund Site near Milan, New Mexico, July 2016." Groundwater samples were collected from pre-selected wells and analyzed for metals (including uranium), alkalinity, ammonia, common ions, nitrogen, gross alpha/beta, radium isotopes, Radon-22, uranium isotopes, stable isotopes, sulfur isotopes, nitrogen isotopes, helium-4, dissolved gases, tritium/helium-3, carbon-14 and chlorofluorocarbons. Groundwater samples were collected using micropurge, volumetric, and passive samplers. Seven different laboratories analyzed the samples; separate datasets containing the results from each laboratory are provided in this data release. Microsoft excel .xlsx, xml, and tab-delimited text files are included for most dataset. A subset of the files are in .csv format.

The data set contained herein were collected as part of a cooperative U.S. Geological Survey and U.S. Environmental Protection Agency (EPA) project entitled "Field Investigations to Help Support the Assessment of Background Concentrations for Uranium (U) at the Homestake Mining Company, Superfund Site near Milan, New Mexico, July 2016.” The site is underlain by alluvial and several consolidated rock units (Chinle and San Andreas aquifers) that contain in some cases elevated concentrations of U above the EPA MCL (maximum contaminant level). Borehole geophysical data were collected from six alluvial wells at the site. Borehole geophysical logs included: induction, fluid resistivity, natural gamma, spectral gamma, fluid temperature, caliper, casing collar locator, optical televiewer, and electromagnetic flow meter logging (ambient and stressed). Geophysical data collected from these wells were used to evaluate well construction, stratigraphy, distribution of potassium, uranium, and thorium, locations of passive sampler deployment and placement, and inflow and outflow intervals of a well under ambient and pumped conditions.

The data set contained herein were collected as part of a cooperative U.S. Geological Survey and U.S. Environmental Protection Agency (EPA) project entitled "Field Investigations to Help Support the Assessment of Background Concentrations for Uranium (U) at the Homestake Mining Company, Superfund Site near Milan, New Mexico, July 2016.” The site is underlain by alluvial and several consolidated rock units (Chinle and San Andreas aquifers) that contain in some cases elevated concentrations of U above the EPA MCL (maximum contaminant level). Borehole geophysical data were collected from six alluvial wells at the site. Borehole geophysical logs included: induction, fluid resistivity, natural gamma, spectral gamma, fluid temperature, caliper, casing collar locator, optical televiewer, and electromagnetic flow meter logging (ambient and stressed). Geophysical data collected from these wells were used to evaluate well construction, stratigraphy, distribution of potassium, uranium, and thorium, locations of passive sampler deployment and placement, and inflow and outflow intervals of a well under ambient and pumped conditions.

High concentrations of uranium were detected in samples from wells used for domestic drinking water supplies in the San Joaquin Valley. Of 163 domestic wells sampled by the California Groundwater Ambient Monitoring and Assessment Program Priority Basin Project (GAMA-PBP) and the National Water Quality Program (NWQP) in 2008-2015, 26 percent had uranium concentrations greater than the U.S. Environmental Protection Agency maximum contaminant level (EPA MCL) of 30 µg/L, with 13 percent of the wells having uranium concentration between 100 µg/L and 450 µg/L. To evaluate the potential anthropogenic and geologic causes of these anomalously high uranium concentrations, Rosen and others (2019) compiled water quality and ancillary data for 450 samples collected between 1993 and 2018 from 257 primarily domestic or public drinking water supply wells sampled by the USGS for GAMA-PBP or NWQP studies. Water-quality data compiled from the USGS NWIS database includes: field water-quality parameters (dissolved oxygen and pH), concentrations of major ions, trace elements, and nutrients, and tritium activities. Groundwater age and oxidation-reduction status classifications were derived from the water-quality data, and equilibrium saturation indices for minerals of interest were calculated from the water-quality data using PHREEQC. Ancillary data compiled for each well site include: well construction information, land use characteristics in 2001 and geologic characteristics. Rosen and others (2019) used graphical and spatial relations, statistical correlations, and principle component analysis to evaluate changes in uranium concentrations over time and infer processes responsible for occurrence of elevated uranium concentrations. They conclude that the process previously identified by Jurgens and others (2010) is responsible for a large part of the observed patterns of increasing uranium concentrations and occurrence of uranium concentrations greater than the EPA MCL - increased bicarbonate concentrations in recharge used for agricultural irrigation causes uranium sorbed on San Joaquin Valley sediments derived from Sierra Nevada granitic rocks to be become soluble. Rosen and others (2019) infer that in addition to solubility enhanced by bicarbonate, the highest uranium concentrations - which were found in the historic discharge zone at the distal end of regional groundwater flow system in the San Joaquin Valley - likely also reflect dissolution of reduced uranium minerals by the more oxic modern recharge water. All of the water-quality and ancillary data used by Rosen and others (2019) are presented in this Data Release. Rosen, M.R., Burow, K.R., and Fram, M.S., 2019 , Anthropogenic and geologic causes of anomalously high uranium concentrations in groundwater used for drinking water supply in the southeastern San Joaquin Valley, California: Journal of Hydrology, v. 577, ppg. 12409, https://doi.org/10.1016/j.jhydrol.2019.124009. Jurgens, B.C., Fram, M.S., Belitz, K., Burow, K.R., and Landon, M.K., 2010, Effects of groundwater development on uranium: Central Valley, California, USA: Ground Water, v. 48, p. 913-928, https://doi.org/10.111/j.1745-6584.2009.00635.x.

High concentrations of uranium were detected in samples from wells used for domestic drinking water supplies in the San Joaquin Valley. Of 163 domestic wells sampled by the California Groundwater Ambient Monitoring and Assessment Program Priority Basin Project (GAMA-PBP) and the National Water Quality Program (NWQP) in 2008-2015, 26 percent had uranium concentrations greater than the U.S. Environmental Protection Agency maximum contaminant level (EPA MCL) of 30 µg/L, with 13 percent of the wells having uranium concentration between 100 µg/L and 450 µg/L. To evaluate the potential anthropogenic and geologic causes of these anomalously high uranium concentrations, Rosen and others (2019) compiled water quality and ancillary data for 450 samples collected between 1993 and 2018 from 257 primarily domestic or public drinking water supply wells sampled by the USGS for GAMA-PBP or NWQP studies. Water-quality data compiled from the USGS NWIS database includes: field water-quality parameters (dissolved oxygen and pH), concentrations of major ions, trace elements, and nutrients, and tritium activities. Groundwater age and oxidation-reduction status classifications were derived from the water-quality data, and equilibrium saturation indices for minerals of interest were calculated from the water-quality data using PHREEQC. Ancillary data compiled for each well site include: well construction information, land use characteristics in 2001 and geologic characteristics. Rosen and others (2019) used graphical and spatial relations, statistical correlations, and principle component analysis to evaluate changes in uranium concentrations over time and infer processes responsible for occurrence of elevated uranium concentrations. They conclude that the process previously identified by Jurgens and others (2010) is responsible for a large part of the observed patterns of increasing uranium concentrations and occurrence of uranium concentrations greater than the EPA MCL - increased bicarbonate concentrations in recharge used for agricultural irrigation causes uranium sorbed on San Joaquin Valley sediments derived from Sierra Nevada granitic rocks to be become soluble. Rosen and others (2019) infer that in addition to solubility enhanced by bicarbonate, the highest uranium concentrations - which were found in the historic discharge zone at the distal end of regional groundwater flow system in the San Joaquin Valley - likely also reflect dissolution of reduced uranium minerals by the more oxic modern recharge water. All of the water-quality and ancillary data used by Rosen and others (2019) are presented in this Data Release. Rosen, M.R., Burow, K.R., and Fram, M.S., 2019 , Anthropogenic and geologic causes of anomalously high uranium concentrations in groundwater used for drinking water supply in the southeastern San Joaquin Valley, California: Journal of Hydrology, v. 577, ppg. 12409, https://doi.org/10.1016/j.jhydrol.2019.124009. Jurgens, B.C., Fram, M.S., Belitz, K., Burow, K.R., and Landon, M.K., 2010, Effects of groundwater development on uranium: Central Valley, California, USA: Ground Water, v. 48, p. 913-928, https://doi.org/10.111/j.1745-6584.2009.00635.x.

This data release contains data on historical water use, spatial land disturbance, and spatial aquifer disturbances related to in situ recovery (ISR) uranium extraction per unit of uranium produced. These data were compiled from published and publicly available references including journal articles, government reports, industry reports and company reporting documents for regulatory compliance and financial reporting requirements. Six uranium ISR mines are represented: Alta Mesa, Kingsville Dome, Mt. Lucas, Palangana, Palangana Dome, and Rosita.

Surface water and groundwater radium activities, concentrations of various dissolved materials, and environmental parameters (water temperature, salinity, and pH). Activities of 228Ra, 226Ra, 224Ra, and 223Ra, as well as 228Th are included in this dataset. Concentrations of dissolved organic carbon (DOC), total dissolved nitrogen (TDN), ammonium (NH4), nitrate + nitrite, nitrite, nitrate, dissolved inorganic nitrogen (DIN), dissolved organic nitrogen (DON), phosphate, chloride, sulfate, total dissolved iron, hydrogen sulfide, dissolved inorganic carbon, methane, and nitrous oxide are included. The radium data are stored in 4 .csv files, one for each study site. The other geochemical data are stored in 4 separate .csv files, again one for each study site.

The risks to wildlife and humans from uranium (U) mining to the Grand Canyon watershed are largely unknown. In addition to U, other co-occurring ore constituents contribute to risks to biological receptors depending on their toxicological profiles. This data was collected to characterize the pre-mining concentrations of total arsenic (As), cadmium (Cd), copper (Cu), lead (Pb), mercury (Hg), nickel (Ni), selenium (Se), thallium (Tl), U, and zinc (Zn); radiation levels; and histopathologies in biota (vegetation, invertebrates, amphibians, birds, and mammals) at the Canyon Mine.