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valley, and shows Ideal conditions under which artesian flow may be encountered. nThe periphery of the valley was studied for the purpose of subsequently being able to deal with demonstrable data, and at this date one can state with certainty that any possibility of water f lotting into the valley through under­ground channels from lakes to the north, or from the Sierra Nevada, is without foundation of fact. The watershed of Las Vegas Valley is the primary source, and although a major part of the precipitation is irretrievably lost by run-off and evaporation, a small part finds its way into porous strata which constitute zones in the old lake deposits, and this water alone creates the inventory which may be tapped and put to beneficial use. Statistics are available for average rainfall at Las Vegas, and although the records are not continuous it appears that a figure of 4-. 88 inches annually would be fairly accurate (Nevada Agricultural Experimental Station). No rainfall stations are maintained at elevations other than at Las Vegas, consequently this figure is not usable for the watershed as a whole. Some research has been conducted in the eastern part of Nevada, and as a result of these published data a ratio of increase equal to 0,4-5 inch per 100 feet of elevation above 2000 feet has been used in calculating total precipitation for the watershed. Accurate data as to recharge factor would be possible only after a protracted schedule of observation, including weiring of all run-off waters and the determination of evaporation