Studies of published and unpublished geologic and ground-water data, for an inventory of 6,032 wells and 754 springs in parts of Inyo and Mono Counties, California, and Clark, Esmeralda, Lincoln, and Nye Counties, Nevada, reveal the following information:
A complex sequence of granitic, metamorphic, volcanic, and sedimentary rocks of Precambrian to Holocene age are present in the study area. Rocks of lower Precambrian age are metamorphic. These rocks can be divided into five principal types: (a) valley fill, (b) volcanic, (c) carbonate, (d) clastic, and (e) metamorphic and granitic. The valley fill which produces large amounts of water is the best aquifer and it contains the largest number of wells. The carbonate and the volcanic rocks produce small to large amounts of water from fractures or solution cavities. The clastic rocks and the metamorphic and granitic racks produce very little ground water.
The greatest concentration of wells in the study area is in the Las Vegas area, which has 79 percent of the total wells inventoried. The Las Vegas area has less than 1 percent of the springs inventoried.
The major uses of ground water listed in order of abundance, for the area exclusive of Las Vegas, are irrigation, domestic, public supply, and industrial. The major uses of ground water listed in order of abundance in the Las Vegas area are domestic, irrigation, public supply, and commercial.
