Selected hydrogeologic data from the Judith Basin, central Montana

Selected hydrogeologic data from the Judith basin, central Montana, have been compiled for use as the physical basis of a ground-water model prepared as part of a 4-year study of Cenozoic and Mesozoic aquifers of the northern Great Plains area of Montana. Records of Cenozoic and Mesozoic aquifers of the northern Great Plains area of Montana. Records of 1,124 wells and 640 springs are tabulated in the report; most of these data have been collected since 1959. Lithologic logs of 68 wells are also included. Chemical data for wells and springs include 290 water samples analyzed for major cation and anion concentrations and 282 water samples analyzed for miscellaneous-constituent concentrations. The locations of wells and springs listed in the report are shown on a map at a scale of 1:250,000. (USGS)