Hydrogeology and hydrogeochemistry of the Spring Mountains, Clark County, Nevada

The Spring Mountains are the largest ground-water recharge area in southern Nevada and supply a significant amount of ground water to the Las Vegas\u27 Pahrump, and Indian Springs Valleys; The high quality of ground water in the study area is controlled by the predominance of carbonate rock in the central portion of the mountain block. Modeling of {dollar}\delta\sp{13}{dollar}C in ground water suggest low P{dollar}\sb{\rm CO\sb2}{dollar} and enriched {dollar}\delta\sp{13}{dollar}C in soil, and open system conditions at high elevations. Analysis of {dollar}\sp{14}{dollar}C in ground water and geochemical modeling of ground water using PHREEQE and BALANCE suggest ground water from the Spring Mountain bedrock aquifer and alluvial-fan aquifers are mixing with water from the regional aquifer in the Las Vegas shear zone. Modeling also suggests mixing of 90 percent Las Vegas shear zone water with 10 percent water from the western portion of the Las Vegas Valley in the Las Vegas well field. (Abstract shortened with permission of author.)