Hydrologic implications of greater ground-water recharge to Las Vegas Valley, Nevada

Published estimates of natural recharge in Las Vegas Valley range between 2 1,000 and 35,000 acre-feet per year. This study examined the underlying ass umptions of previous investigations and evaluated the altitude-precipitatio n relationships. Period-of-record averages from high altitude precipitation gages established in the 1940s through the 1990s, were used to determine s trong local altitude-precipitation relationships that indicate new total pr ecipitation and natural recharge amounts and a new spatial distribution of that recharge. This investigation calculated about 51,000 acre-feet per yea r of natural recharge in the Las Vegas Hydrographic Basin, with an addition al 6,000 acre-feet per year from areas tributary to Las Vegas Valley, for a total of 57,000 acre-feet per year. The total amount of natural recharge i s greater than estimates from earlier investigations and is consistent with a companion study of natural discharge, which estimated 53,000 acre-feet p er year of outflow. The hydrologic implications of greater recharge in Las Vegas Valley infer a more accurate ground-water budget and a better underst anding of ground-water recharge that will be represented in a ground-water model. Thus model based ground-water management scenarios will more realist ically access impacts to the ground-water system.