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Show June 25, 1929. This compact3 apportioned "in perpetuity to the upper basin and to the lower, respectively, the exclusive beneficial consumptive use of 7,500,000 acre-feet of water per an- num * * *." In addition, 1 million acre-feet a year were apportioned to the lower basin. Pro- vision also was made to protect any Mexican rights to the waters of the Colorado to be later agreed to by treaty.* Stipulation further was made that the supply to the lower basin would not be depleted an "aggregate of 75,000,000 acre-feet for any pe- riod of 10 consecutive years * * *."5 Any surplus water over and above that apportioned may be divided among the States after October 1, 1963 "if and when either basin shall have reached its total beneficial consumptive use." The fierce competition for water was by no means allayed by the agreement. The apportionment of water between the States of the upper basin was not finally determined until 1948, and negotiations on the apportionment of the lower basin water now are deadlocked. The eventual division of the surplus water of the basin also will be an extremely difficult matter for agreement. The difficulties to be faced in water develop- ment are of two types-physical and economic. The Colorado River carries a heavy load of sedi- ment. Mian's occupancy of the basin has accel- erated the rate of sediment movement. How to lessen the rate of sedimentation is known reason- ably well at present, but no one knows if it is possi- ble to stop it. There are scarcely the rudiments of a program to slow the process. Another physical difficulty is the rough terrain, with the river set in deep canyons requiring costly facilities consisting of high dams and long canals and tunnels to carry the water to agricultural lands. Also the length of the river, from its source in the mountains to the lands where the water is used, permits great evaporation losses, reducing the supply available for use. Present economic problems relate principally to irrigation. All lands easily irrigated are developed. Expansion, requires very large and expensive struc- tures far exceeding the irrigator*s repayment ability on most projects. Additional sources of funds will be necessaiy. Perplexing problems of single versus multiple-purpose structures and of interregional and interstate relations are a part of the situation. 3 Art. 3, sec. (a). 4 Art. 3, sec. (c). 8 Art. 3, sec. (d). Under present Federal law little expansion of irri- gable lands is possible until these conflicts are resolved. In parts of the lower basin, dependence on dwindling supplies of underground water will cause some irrigated lands to cease production unless additional water is obtained. The potenti- alities of the basin can be exploited fully only if adequate solutions to these problems are found. The areas that can be most easily irrigated are small and are located in the upper reaches of tribu- tary streams which have not yet become en- trenched. Of these the best have already been irrigated. Several diversions from the basin have previ- ously been made, especially in the upper basin States, where water can be applied to land in other basins. Plans have been made for several addi- tional diversions from the Colorado into other river basins. Each State under the Colorado River Compact-the "law of the river"-can divert water under its apportionment. While the general nature of basin problems may be described simply, the complexity of basin devel- opment for efficient water resources use cannot be overemphasized. Indeed, nothing is simple in the Colorado Basin when examined closely. Policy problems therefore must be examined in the light of the varied natural environment, the divergence of sectional interests within and adjacent to the basin, the varied history of occupancy, and the size of the area. Physical Characteristics The Colorado Basin extends from Wyoming on the north into Mexico on the south, and from the western slope of the Rocky Mountains to the Gulf of California. Comprising an area of 242,000 square miles in the United States and 3,000 square miles in Mexico, the basin includes southwestern Wyoming and western Colorado, parts of Utah, Nevada, and New Mexico, virtually all of Arizona, and part of southern California. The State areas in the basin are shown in table 1. Topographically, the northern three-fourths of the Colorado Basin consists of series of vast, high, arid plateaus covered by a scanty growth of desert shrubs and grasses. The plateaus are surrounded by high, relatively humid mountains clothed with forests-the middle Rockies on the west and north and the southern Rockies of Colorado on the east. 356 |