This report is the eleventh in a series by the U.S. Geological Survey in cooperation with the Utah Department of Natural Resources, Division of Water Rights, which describes the water resources of the western basins of Utah (fig. 1). Its purpose is to present hydrologic data for the Promontory Mountains area, to provide an evaluation of the potential water-resource development of the area, and to identify needed studies that would improve understanding of the area's water supply.