Ground-water resources of Kyle and Lee Canyons, Spring Mountains, Clark County, Nevada

Abstract

Kyle and Lee Canyons are in the Spring Mountains of southern Nevada about 25 miles northwest of Las Vegas. There is concern that septic-tank effluent may be affecting ground-water quality in both canyons. This study evaluates the ground-water system and the quality of ground water in each canyon. The bedrock of the study area consists of Paleozoic limestone, dolomite, and minor clastic rocks that have been offset by thrust and high-angle faults. The bedrock is overlain by Pliocene and Pleistocene alluvial and colluvial fill that is at least 150 feet thick in Lee Canyon and 400 feet thick in Kyle Canyon. The estimated hydraulic conductivity of Paleozoic carbonate rocks ranges from 0.04 to 5 feet per day. However, these estimates may be low by as much as several orders of magnitude. The estimated hydraulic conductivity of alluvium in Kyle Canyon is 50 feet per day on the basis of drillers' well tests. The estimated specific yield of the alluvium is 12 percent. Ground water occurs in the carbonate rocks and alluvium of Kyle Canyon and the carbonate rocks of Lee Canyon (the alluvium of Lee Canyon is rarely, if ever, saturated). Most ground water moves generally eastward toward Las Vegas Valley, although flow to other adjacent basins is also possible. Estimated average velocities of ground-water movement are about 30 feet per day in the alluvium of Kyle Canyon and range from 0.2 to 3,000 feet per day in the carbonate rocks of both canyons. Each year, ground-water levels in both canyons rise during the spring and early summer in response to the snowmelt, then decline to a base level by late fall or early winter. During 1980, measured water levels fluctuated 41 to 134 feet in Kyle Canyon and 8 to 27 feet in Lee Canyon. Water-level changes appear to be due to changes in pressure head in the carbonate rocks, rather than to a slug of snowmelt moving downgradient through the system. Snowmelt is the primary source of recharge to the ground-water reservoir of each canyon. Discharge occurs as underflow to Las Vegas Valley and possibly to other adjacent basins. Kyle and Lee Canyons receive about 5,000 and 3,000 acre-feet per year of recharge, respectively. Discharge from the two systems by way of carbonate rocks cannot be estimated because the saturated thicknesses are not known.