Geothermal investigations in Idaho, Part IV, Isotopic and geochemical analyses of water from the Bruneau-Grand View and Weiser areas, Southwest Idaho

Variations of deuterium and oxygen-18 concentrations in thermal ground waters and local nonthermal springs have been used to aid in describing the source of recharge in the Bruneau-Grand View and Weiser areas, southwest Idaho. Isotope and geochemical data for the Bruneau-Grand View area suggest that recharge to the area may not be entirely from sources within the local surface-drainage area, but possibly from the areas of higher altitude of the Bruneau River drainage to the southeast; or that the hot water that wells and springs are discharging is water that was recharged at a time when the regional climate was much colder than the present climate. Recharge to the Weiser area is probably from areas of higher altitude to the north and northeast of the local drainage area However, local precipitation does influence both the chemical and isotopic compositions of the waters in each area.