By: J. C. Stephens and J. W. Hood
Pilot Valley is an area of about 470 square miles in southwestern Box Elder and northwestern Tooele Counties, Utah, and eastern Elko County, Nevada. The valley is bounded on the east and south by the Silver Island Range, and on the west by the Pilot Range. The bottom of the valley, about two-thirds of which is a barren alkali flat, is part of the Great Salt Lake Desert. The climate of Pilot Valley is arid to semiarid. The principal source of runoff and ground-water recharge is the snow pack that accumulates on the mountains in winter. Total precipitation on the area averages about 184,000 acre-feet annually, and nearly the entire amount ultimately is consumed by evapotranspiration within the valley. The only perennial streamflow in the area occurs in short spring-fed reaches above altitudes of about 5,600 feet. Below that altitude the flow is lost to infiltration and evaporation. The ground-water reservoir in Pilot Valley consists of unconsolidated materials of Quaternary and Tertiary age and consolidated sedimentary, metamorphic, and igneous rocks ranging in age from Precambrian to Tertiary. Annual ground-water recharge is estimated to be 7,500 acre-feet. About 3,400 acre-feet of recharge is derived from precipitation on the area above an altitude of 5,600 feet. The remaining 4,100 acre-feet of recharge is ground-water inflow from adjacent areas.
Its purpose is to present available hydrologic data on the Pilot Valley area, to provide an evaluation of the potential for water-resource development in the area, and to identify studies that would improve understanding of the area's water supply.
Plate: 1 pl.
Location: Box Elder County and Tooele County
Media Type: Paper Publication