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

page 150

150 CENTRAL ARIZONA PROJECT 3. WATER SUPPLY (a) New water available Under the central Arizona project, new water would be developed from four rivers, namely: First, the Colorado River by diversion from Havasu Lake; Second, the Verde River by enlargement of Horseshoe Dam; Third, the Gila River by construction of Buttes and Hooker Dams, and the Safford Valley improvements; and Fourth, the San Pedro River by construction of Charleston Dam. (1) Diversions from the Colorado River.-Development of the Colorado River has caused a gradual decrease in the average annual flow and may be expected to continue to reduce the flow in the future. It is estimated that if no man-made developments existed in the basin, the long time (1897-1943) average annual run-off of the Colorado River at Lee Ferry would be 16,270,000 acre-feet. This is termed virgin flow. The flow at Lee Ferry has been selected for analysis as this point on the Colorado River marks the division between the upper and lower basins. (Lee Ferry is a point in the main stream of the Colorado River 1 mile below the mouth of the Paria River. It should not be confused with the Geological Survey gaging station, Lees Ferry, one-fourth mile upstream from the mouth of the Paria River). It is further estimated that the virgin flow of the Colorado River at the international boundary would average 17,720,000-acre-feet annually. Included in this figure is an estimated average annual contribution from the Gila River of 1,270,000 acre-feet. Apportionment of this water among the various States in the Colorado River Basin has long been a source of controversy and the subject of negotiations. This report makes no attempt to allocate water to States or among projects within States. However, some assumption as to the amount ultimately available for diversion to central Arizona is necessary. A compact, treaty, and numerous contracts and agreements deal with the distribution of the waters of the Colorado River. These include the Colorado River compact, the Arizona contract, various other contracts with the Secretary of the Interior for delivery of Colorado River water, and the treaty between the United States and Mexico. Unfortunately, there are several interpretations of some of these documents. Because these are legal questions which cannot be arbitrarily settled by the Bureau of Reclamation, it is impossible to determine with finality the amount of water available to the State of Arizona from the Colorado River. The interpretations of all compacts and contracts, as used for a basis of computation in this report, are those of responsible officials of the State of Arizona. The interpretations thus expressed are not necessarily those of the Bureau of Reclamation or of all other States of the Colorado River Basin. Computations, consistent with interpretations by Arizona, are briefly summarized in the following tabulation: