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t:: i- 3 \:J Outstanding among the potential irrigation projects listed in the Report is the Colorado River-Central Arizona project, involving an estimated construc- tion cost of $462,900,000, which alone is greater than the costs of all other irrigation projects in all seven States of the Colorado River Basin (that together total $302,845,000). It contemplates diversions of Colorado River water from the potential :Bridge Can;yon reservoir, through a tunnel 80-miles long to Big Sandy River, a tributary of the W11liaIDB River, and thence via a canal 270'"lll11es long to Salt River, and includes 8-units in the Gila River Basin, each with canal and reservoir facilities, to serve 107,000 acres of nw land and provide supplemental supplies for about 593,000 acres. Unit costs of the project are e'luivalent to about $4,300 per acre of new land, or $660 per acre of land benefited, and to about $290 per acre foot of water to be diverted from the Coloxado River. By reason of the distances to which the water would be conveyed, the opportunities for rediversion and loss of return flows, and the excessive channel losses known to exist in the Gila River between Central Arizona and its mouth in the Colorado River near the Mexican border, the Colorado River- Central Arizona project is similar in its effects to so-called export diver- sions in the Upper Basin for use outside the natural basin, and is not unlike those to the basin of BaHon Sea and to Pacific Coast drainages in southern California. All of these in the Lower Basin should be so classified and separately summarized in the Report, in the same manner in which similar projects are treated in the Upper Basin, 12. POTENTIAL EXPORT DIVERSIONS. Much of the summary data of the Report, cooeernin{! potential export Clivers:lone from the Upper Basin, must be revised. Estimated diversion 'luantities shown as averages for drought-cycle (1931-1940) conditions should be shown also, if not exclusively, for normal conditions. All projects for diverting water from one tributary to another, and from one division to another, within the natural basin, should be excluded from the depletion and cost summaries of export diversion projects. This mayor may not rB'luire revisions in the depletions and cost summaries of potential irrigation projects. In several instances the potential export diversion projects are charged to the wrong State. (17)