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Show use of 7.5 million in the upper basin could not be justified with shortages and curtailments approach- ing 50 percent being imposed year after year for a 10-year period. On the other hand, prior to 1930,10-year natural flows at Lee Ferry in excess of 170 and 180 million acre-feet were prevalent in every recorded period. With sufficient holdover capacity in reservoirs, it would be possible to carry over the high flow dis- charges for later release during drought periods. Storage tbrus is of vital necessity in planning future actions on. the upper river. The holdover waters would be released in exchange for upstream uses up to 7.5 million acre-feet annually. In this man- ner a complete, uncurtailed use of apportioned water could be accomplished in the upper basin without any violation of the obligations imposed by the Colorado River Compact. As a first step toward unified development in the upper basin a regulatory system, the Colorado River Storage Project, is being suggested by the Bureau of Reclamation. The project plan, in addi- tion to its regulatory purposes for water conserva- tion, includes other purposes among which are power generation, sediment retention, flood con- trol, recreation, and fish and wildlife conservation. Based on preliminary studies, the plan assures ulti- mate water resources use within the limit of water allocation to the upper basin. The States of the upper basin have indicated their approval of the plan in principle and a report is about to be sub- mitted to all States of the Colorado River Basin and the various interested Federal agencies for re- view and comment under the procedure of the Flood Control Act of 1944.9 Under the terms of the Upper Colorado River Basin Compact, each State has reserved its right to utilize wholly or jointly any of the available reservoir sites on the Colorado River and its tribu- taries if such is necessary to effect a use of its ap- portioned Tvater. The regulatory reservoirs of the Colorado Hiver must give way to that reservation. Power production at the regulatory sites is also subject to> diminution as upstream consumptive uses are brought in. This emphasizes the need for early construction of the regulatory reservoirs in order that full advantage can be attained from the undepletecl flow, thus assuring more rapid amor- tization of downstream project costs. Present irrigation developments have generally utilized the upper basin's least expensive and most •Act of December 22, 1944, § 1, 58 Stat. 887. convenient sources of water supply and as a rule the new developments will be required to construct expensive storage structures and extensive systems of diversion. In general the costs of project works are in excess of the repayment ability of the irri- gators. Compatible with the process of river regulation is hydroelectric power generation. Power market studies of the Federal Power Commission and the Bureau of Reclamation indicate that the full output of the power plants under the Colorado River Stor- age Project could readily be absorbed under a 20- year orderly construction program. At least 750,- 000 kilowatts additional capacity will be needed in the upper basin within 20 years. The total costs of the Colorado River Storage Project (including total annual operation, maintenance and replacement costs, power investment with interest at 3 percent on power plants, transmission lines, and an appro- priate portion of the joint storage facilities, and the remaining joint costs) are all allocated to power and are to be repaid from power revenues within a period of 50 years from the time the investment is incurred. The Bureau of Reclamation estimates that a total active capacity of 23 million acre-feet will be re- quired to provide the necessary regulation. In ad- dition there must be provided some 20 million acre- feet of capacity for the storage of sediment, offering 200 years of protection prior to any sediment en- croachment on the capacity allotted to regulation. Some additional dead storage space must be pro- vided to assure the heads necessary for hydroelectric operations. In addition the States will participate in the joint use of some sites in connection with bringing about their allotted consumptive uses. In all, a total capacity of about 48 million acre-feet will be required. After inspecting the characteristics of a number of reservoir sites in the upper basin, a system con- sisting of 10 dams with reservoirs, power plants, and interconnected transmission system was selected on the basis of producing the desired river regulation and a maximum amount of hydroelectric energy, with a minimum cost and charge to evaporation (table 19). The units proposed for first construction under the Colorado Storage Project plan are Echo Park, Flaming Gorge, Glen Canyon, Martinez, and Bridgeport. In general the proposed irrigation projects will encompass nearly all future development in the upper basin; however, private undertakings or self- 458 |
