During the past few years of drouth the importance of ground-water supplies has become more fully appreciated. During this time, because of subnormal replenishment of the ground-water reservoirs and the increased withdrawals from wells, the ground-water levels have declined in most developed areas in the State, a condition which has made the well owners acutely aware that ground water is not inexhaustible. Numerous cases of contention between well owners resulted in increased demands for adequate regulation of the appropriation and use of ground water. Realizing that more information concerning the ground water of the State was imperative, not only to administer the ground-water regulations but to prepare for the conservation and replenishment of existing supplies and development of new supplies, the State Legislature enacted, during its 1935 session, Senate Bill 206, which authorized the State Engineer to make an investigation of the ground water of the State. To provide for the expenses of the investigation, the bill allotted /$10,000 to the State Engineer, this sum to be matched by a State or Federal organization, and the investigation to be carried out co-operatively during the biennium beginning July 1, 1935. A co-operative agreement between the State Engineer and the United States Geological Survey was made on July 1, 1935.