Data Associated with Uranium Background Concentrations at Homestake Mining Company Superfund Site near Milan, New Mexico, July 2016 through October 2016

To help characterize the groundwater system at Homestake Mining Company Superfund Site near Milan, New Mexico, the U.S. Geological Survey collected borehole geophysical and groundwater-quality data in cooperation with the U.S. Environmental Protection Agency during JulyOctober 2016. The following borehole geophysical data were collected from wells at or near the Homestake Mining Company Superfund Site: induction, fluid resistivity, natural gamma, spectral gamma, fluid temperature, caliper, casing collar locator, optical televiewer, and electromagnetic flow meter logging (ambient and stressed). The geophysical data were used to evaluate well construction, stratigraphy, distribution of potassium, uranium, and thorium, locations of passive sampler placement, and inflow and outflow intervals of a well under ambient and pumped conditions; information obtained from the geophysical data aided in the collection of groundwater samples. Groundwater samples were collected by using micro-purge, volumetric, and passive samplers. As of June 2017, the following constituents have been analyzed and are documented in this data release: major ions, alkalinity, ammonia, nitrogen, trace metals, gross alpha/beta, radium isotopes, radon-22, stable isotopes, sulfur isotopes, nitrogen isotopes, helium 4, dissolved gases, tritium/helium 3, and chlorofluorocarbons. The uranium results are still pending and will be added to the data release when they become available. Five different laboratories analyzed the samples; separate datasets containing the results from each laboratory are provided in this data release.