The hydrogeochemistry of the principal aquifers in Las Vegas Valley, Nevada and the chemical effects of artificial recharge of Colorado River water

Abstract

Chemical analyses of samples collected from 32 wells in the principal aquifers in Las Vegas Valley indicate that water chemistry varies throughout the aquifer, reflecting lithologic variations in aquifer material and specific sources of recharge. Chemical species and mineral saturation indices plotted on maps and diagrams, and Q-mode factor analyses delineate three groups located in west central, northern, and southern Las Vegas Valley. In west central Las Vegas Valley, decreasing sulfate, calcium, and magnesium and increasing bicarbonate along the flow path suggests that a higher sulfate water from the southwest is mixing with a higher bicarbonate water from the northwest. However, the data suggest recharge from a deep carbonate rock aquifer may also be causing this trend. Calcite saturation indices calculated from chemical analyses of treated Colorado River water suggest that calcite may precipitate near the well during artificial recharge of this water into the principal aquifers.