AZ vs. CA:25 California Exhibits, Vol. XXV; Nos. 7501-7859

page B-64

B. WATEE SUPPLY (3) Availability of Colorado River water (a) General. Hydrological data and legal documents appearing in other sections of this appendix are herein used to determine the amount of Colorado River water available to the State of Arizona. In addition, consideration is given to present and future depletions of water in the Lower Basin by Arizona as listed in the Bureau of Reclamation report entitled "The Colorado River" and dated March 19^6. These depletions subtracted from water available to Arizona plus water estimated to be returned to the Colorado River by Arizona result in the, amount of water available for diversion to the Central Arizona Project from the Colorado River. In some cases there is disagreement on the interpretations of certain legal documents pertaining to the apportionment of water to the individual state. Where these variances occur, interpretations by responsible officials of the State of Arizona are used. It is recognized that these interpretations are not necessarily supported by all states in the Colorado River Basin. (b) Unapportioned water. In calculations concerning the availability of Colorado River water under ultimate conditions, it should be assumed that the average annual virgin flow as determined at the International Boundary will be depleted the full amounts apportioned by the Colorado River Compact under Article III (a) and (b), and allotted by the Treaty with Mexico. These apportionments amount to 17,500,OCO acre-feet per annum. The annual virgin flow of the Colorado River at the International Boundary has been computed at 17,720,000 acre-feet. The difference between these two figures equals the amount of unapportioned water or 220,000 acre-feet. (c) Water for use by Arizona. Arizona contends that of the 8,500,000 acre-feet of water apportioned annually to the Lower Basin by the Colorado River Compact, California may use no more than ^,^00,000 acre-feet as stipulated under its Limitation Act of March k, 1929. Nevada has contracts for uses totaling 300,000 acre- feet of the apportioned water. Subtracting California and Nevada's allocations from the 8,500,000 acre-feet, leaves 3,800,000 acre-feet for Arizona. Arizona officials recognize the rights of Utah and New Mexico to use cf waters in the Lower Basin. It is estimated that ultimate developments by Nev Mexico will deplete annually the Little Colorado River by 13,000 acre-feet and the Gila River by 16,000 acre-feet. Under ultimate development, it is estimated that Utah annually will deplete the Virgin River by 9^,000 acre-feet and Kanab Creek by 7,000 acre-feet. Therefore, ultimate depletions in the Lower Basin by these states are estimated at 29,000 acre-feet by New Mexico and 101,000 acre-feet by Utah or a total of 130,000 acre-feet.