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3 001294 estimated 387,000 acre-feet of water per year; and many more miles of ditch are lined each year. Of course, all irrigation districts in Central Arizona measure water deliveries. Organized irrigation districts in the State have lined with concrete or piped more than 2,000 miles of delivery canals and laterals to reduce water loss. The Salt River Project, largest irrigation district in the State, has spent $1 S, 000,000 during the last 15 years on works to conserve water and deliver it more efficiently. This program is continuing. Two of the smaller districts in the Salt River Valley have current water- saving programs in process with loans obtained under the Small Reclamation Projects Act. In combination these two projects alone will save in excess of 15,000 acre-feet annually. The Soil Conservation Service reports that more than half of Arizona's irrigated croplands have been releveled to improve efficiency and to prevent waste of water from the lower ends of fields; and 207 pump-back systems have been built (28 of them in 1965) to receive unavoidable waste water in sumps from which it is pumped for reuse. The investment by farmers in these water saving methods is approximately $65,000,000. PUMPING CONTROLS Almost all irrigated land in the State is now included in districts called "critical areas" under the Arizona Ground Water Code of 1948. In these areas it is illegal to drill new wells to bring new land into cultivation. However, depletion of ground water continues to be a serious problem because of pumping that is essential to maintain the existing economy in areas that were developed for irrigation before the limitations of the Code were applied. In this connection it must be recognized that in 1928 the Congress allo- cated to Arizona the right to use 2,800,000 acre-feet of Colorado River water annually, and that since then Arizonans have confidently planned for and expected to use a large part of that water to relieve their ground water overdraft problems. That this has not yet come about is beyond their control. Reduction of the State's overdraft on ground water is the major purpose of the proposed Central Arizona Project to bring in Colorado River water. The delivery of this surface water would enable Arizona to better manage and conserve its dwindling ground water resources. The Project would deliver no water for expansion of irrigated acreage. HIGH COST SAVES WATER The cost of water for irrigation in Arizona also provides a strong motive for its conservation and efficient use. Surface water is of course the cheapest water available.