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<br />virzin flow of the river at Lee Ferry is approximately 14 million <br />acre-feet per year (maf/yr). <br /> <br />Present uses and losses in the Upper Colorado River Basin <br />currently total about 3.9 maf/yr. By 1990, Upper Basin uses and <br />losses are conservatively projected to be about 4.2 maf/yr., with <br />grow+-,h beyond 1990 dependent to a large extent upon the uncertain <br />rate of development of the region's huge reserves of oil shale <br />and coal. While projections of that rate have been quite varied, <br />general agreement is found among all researchers that the Upper <br />Basin use will not reach 5.8 maf/yr. until several years after the <br />turn of the century. This level of use is further discussed under' <br />the heading, "Colorado River Compact". <br /> <br />In the Lower Basin, Arizona will increase its present use of <br />:nainstream water of 1.1 maf/yr to its maximum apportionlnent from the' <br />:::ainstrea:"l, 2. <5 maf/yr, starting in the mid-1980s upon completion <br />of the Central Arizona Project. Nevada's current use rate of <br />approximately 100,000 acre-feet/yr will probably increase to its <br />Llll apportionment of 300,000 acre-feet/yr. by or after the year <br />2JOO. <br /> <br />California is currently using about 4.9maf/yr. When the <br />Central Ari,zona Project begins de: i veries, it is anticipated that <br />California's use will be reduced to its 4.4 maf/yr. basic apportion- <br />::lent. <br /> <br />Mexico is guaranteed 1. 5 maf/yr. under the terms. of the Treaty. <br />Losses in the Lower Basin which are not replaced by Lower Basin <br />tributary inflow constitute an additional drain of 600,000 acre-.feet/yr. <br />on the river. The sum of these requirements on the ri ver syste;~ <br />currently total about 12.1 maf/yr., and would total about 13. <3 mar/yr. <br />by the year 1990. <br /> <br />As annual uses in the Upper Basin continue to increase after <br />:.990, water could be drawn from reservoir storage at a rate equal <br />to the incremental increases in Upper Basin uses above their 1990 <br />uses. After the stored water is withdrawn .to where the reservoirs <br />are at minimum operating levels, then, as uses continue to increase <br />in the Upper Basin up to the projected r~aximum level of 5. S maf/yr., <br />the Central Arizona Project diversions would have to be reduced so <br />t,:1at the total demands are in bale.nce with the long-ter:n average <br />annual supply. A portio\1 or t.he Southern Nevada VlatGr P~'oject <br />diversions would also have to be reduced in accordance with the <br />appx:opriate language in Pt1bl~c Law 90-537, the Colorado River R"\sin <br />ProJect Act. <br /> <br />\ <br />Colorado River Compact <br /> <br />The basic apportionments between the Upper and L~Ner Basins <br />of the Colorado River are established by the Colorado River Compact. <br /> <br />C-18 <br />