AZ vs. CA:22 California Exhibits, Vol. XXII; Nos. 5001-5002; 5101-5123; 5200A-5205A; 5521-5588A; 5601-56215521-5588A; 5601-5621

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COLORADO RIVER STORAGE PROJECT 13 At a point 15 miles below Glen Canyon Dam site, the Paria Kiver contributes an average of about 25,000 acre-feet annually to the Colorado River, but the flow is erratic from year to year. For all practical purposes the flow at Glen Canyon approximates the flow at Lee Ferry, 16 miles downstream, the dividing point on the river between the upper and lower basins. The average annual virgin flow at Lee Ferry over the 1914-45 period is estimated at about 15,640,000 acre-feet. STEEAM DEPLETIONS Annual man-made depletions in the Upper Colorado River Basin from existing developments and developments authorized prior to 1949, the year the Upper Colorado River Basin compact became effective, are estimated to average about 2,550,000 acre-feet. A number of years will be required for full development of projects authorized prior to 1949. The 2,550,000-acre-foot depletion is therefore used in this report as also applying to fiscal year 1963, when initial operation of the storage project is scheduled and is also referred to as the present depletion. On the basis of the annual depletion of 2,550,000 acre-feet, the upper basin is utilizing only about one-third of the consumptive use apportioned to it by the Colorado River compact. As a basis for evaluating the Colorado River storage project and participating projects, a projection was made of future stream depletions estimated to occur in the upper basin during the 100-year period from fiscal year 1963 through fiscal year 2062. It was estimated that the depletions by 2062 would total about 6,191,000 acre-feet annually, consisting of 2,550,000 acre-feet from existing developments, 691,000 acre-feet from evaporation from the authorized storage units, and 2,950,000 acre-feet from new projects including the authorized participating projects and other future Federal and non-Federal developments. The 2,950,000-acre-foot depletion from new projects expressed as a weighted average amount over the 100-year period approximates 1,800,000 acre-feet, a figure used hereinafter in the project economic analysis. Assumed average depletions are summarized in the table below. Projected depletions x [In thousand acre-feet] Fiscal year Depletion from existing and new projects in upper basin Average evaporation losses from storage units' Total 3963 2,550 3,150 4,750 Negligible 691 691 2,550 3,841 5,441 1970.... 2020...-....... 2062 5,500 691 6,191 1 Based on averages for runoff period 1914 to 1945, inclusive. > Estimated average stream depletions due to evaporation from Glen Canyon, Flaming Gorge, Navaho, .ind Curecanti storage units. EEPLACEMENT STORAGE The holdover reservoirs in the Upper Colorado River Basin are designed to impound water in years of high runoff and release such water during prolonged dry periods to permit the upper basin to