AZ vs. CA:11 California Exhibits, Vol. XI; Nos. 1001-1011; 1101-1109; 1201-1251; 1301-13431301-1343

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-14- SILT The Colorado River board adopted a figure of 137,000 acre-feet as the annual silt load of the Colorado River compared with a previous bureau estimate of 80,000 acre-feet. The estimates of upstream development contemplate reservoirs with a total capacity of 11,000,000 acre-feet, of which some 8,000,000 acre-feet would be in power reservoirs principally at the lower ends of the main tributaries. Construction of the Bridge Canyon Dam is included with an active storage capacity of 1,000,000 acre-feet. The upper reservoirs will materially reduce silt flow while Bridge Canyon would almost completely stop silt flow into Boulder Canyon. The silt accumulation during the repayment period has been assumed at 3,000,000 acre-feet with a maximum deposit at a level slightly below the average storage level. POWER OUTPUT Plant efficiency. The following efficiencies have been assumed in all operations: Per cent Penstocks ............................................................................ 97 Turbines .............................................................................. 90 Generators ..................................................i........................ 96 Transformers .................................................................... 99 Net over-all efficiency........................................................ 83 Firm power. Run-off records on Colorado River extend over a period of 37 years from 1895 to 1932. No other stream in this locality has longer records. Great Salt Lake obtains most of its inflow from the western slope of mountains, the eastern side of which drain to the Colorado River. Inflow to Great Salt Lake can be estimated for the past 78