The Lower Colorado River Basin Project Senate Report

Document: 88th Congress, 2d Session, Senate Calendar No. 1267, The Lower Colorado River Basin Project, Report No. 1330, Agust 6, 1964, page 77 THE LOWER COLORADO RIVER BASIN PROJECT Under the Colorado River compact the States of Colorado, New Mexico, Utah, and Wyoming may not deplete the flow of Colorado River at Lee Ferry below an aggregate of 75 million acre-feet in any 10 consecutive years. All the planning for the lower basin is predicated on the assumption that there will be no increase in the burden on the upper basin beyond this delivery requirement at Lee Ferry, plus its share of the Mexican treaty obligation. Glen Canyon Dam has already been built so that the upper basin development can proceed and the upper basin still be able to meet the commitments of delivery to the lower basin. The Secretary of the Interior, under the Boulder Canyon Project Act, has entered into contracts with Arizona, California, and Nevada users for more water than the upper basin is required to make available. Thus, as the upper basin develops new projects to utilize its share of the Colorado River, the amount of water remaining for use in the lower basin will decrease. If the conditions of adverse streamflow experienced since the 1930's persist or recur, the amount available for the lower basin from the main stream may go below 7,500,000 acre-feet. Thus, one of the major purposes of the bill is to augment the limited supply which will be available to the lower basin after the upper basin is meeting no more than its burden under the compact. The Commissioner of Reclamation advised the subcommittee in August 1963, that for the 10 years ending in 1962, the average annual flow past Lee Ferry was slightly less than 10 million acre-feet, down from an average somewhat in excess of 18 million acre-feet of virgin flow or some 16 million acre-feet of historic flow during the 10-year period ending in the early 1920's. Based on what the Commissioner of Reclamation described as conservative estimates of runoff and optimistic estimates of the buildup of upper basin uses, it would appear that the lower basin States will have a Colorado River supply of 7.5 million acre-feet until 1975, after which, barring a return to favorable flow conditions there may be a decline below that figure. Uses from the main stream in the lower basin are now about 5,775,000 acre-feet annually. Under the Court decree and assuming only 7,500,000 acre-feet available in the river California would have a legal right to no more than 4,400,000 acre-feet, while Arizona and Nevada could increase their uses from their present levels of 630,000 and 20,000 to 2,800,000 and 300,000 respectively. Qualified technicians estimate that uses in the lower basin will increase by about 1990 to the point where, without having either favorable flows or the development of supplemental water, a formula to allocate shortages will have to be devised and applied. The Supreme Court considered this eventuality but declined the enunciation of a formula. Some California users have contended allocations should be based on the State law principle "first in time, first in right." This would give California a priority to 4,400,000 acre-feet superior to Arizona and Nevada's uses not yet initiated. Arizona has contended that the allocation should be based on priority in proportion to entitlement. The supreme Court held that the Secretary could, but was not obliged, to follow either method. The effect of the two methods on the water supply available to the Central Arizona unit is compared in the attached table:Epson Perfection 4870 Photo, 400 dpi, 8 bit, 1,796,117 byte