In common with many of the arid and semiarid States, the prosperity of Utah probably is more dependent upon the amount of water available than upon any other natural resource. Although only about four per cent of the State is irrigated, a shortage of water for irrigation becomes a major calamity. A large part of the water‐supply for the State is derived from surface‐streams, but a most valuable supplement to this supply is the water available from underground sources. Ground‐water is used extensively for domestic, stock‐watering, and industrial purposes as well as for irrigation. The primary source of the municipal water‐supply for Salt Lake City is from streams entering the Jordan River Valley from the western slope of the Wasatch Mountains. However, since the drought‐year of 1931, a supplementary municipal supply has been obtained from ground‐water, and, among the 17 wells developed by the City during the extreme drought of 1934, one—yielding about ten cubic feet per second, or 4500 gallons a minute—is probably the largest in the State. Ogden, the second largest city in Utah, with a population of about 40,000, obtains the major part of its municipal water‐supply from a group of artesian wells in Ogden Valley about 12 miles east of the City. A considerable part of the water‐supply for the City of Brigham is obtained from wells. Springs constitute the source of most of the water‐supply for Logan, Provo, and many smaller towns and localities in the State. In nearly every developed area of the State ground‐water is used for some purpose, and in some areas the water‐supply is obtained almost entirely from wells.