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<br />r"~ <br /> <br />42. Sediment deposited in the reservoir for the period October <br /> <br />N <br />~ 1966 through March 1972, computed from suspended sediment sampling, was <br />""') <br />~ 4,076 acre-feet, as shown in table 8. A density of 75.7 pounJs per <br /> <br />cubic foot was used for these computations nnd allowance "as made for <br /> <br />consolidation. The density of the most recent sediment deposits, from <br /> <br />38 sediment samples taken just after the resurvey, varied from 60.7 <br /> <br />to ~9. 5 pounds per cubic foot. The average of all samples was 80.0 <br /> <br />pounds per cubic foot. Table 9 lists the 38 samples in upstream order <br /> <br />from the dam. An overall increase in the dry weight from the dam to the <br /> <br />upper reaches cnn be noted. <br /> <br />43. 111e size analyses of the deposited sediment shows an estimated <br /> <br />20 percent sand, 44 percent siIt, and 36 percent clay. Size analysis for <br /> <br />the 196(i resurvey showed an estimated 3 percent sand, (,3 percent silt, <br /> <br />and 34 percent clay. The samples taken in 1066 reflect the effects of <br /> <br />the June 1%5 flood which carried large quantities of fine material and <br /> <br />very little sand. Average size analysis of the inflows indicates approx- <br /> <br />imately 10 percent sand, 70 percent silt, and 20 percent clay. The trap <br /> <br />efficiency of the reservoir for the entire period of operation has been <br /> <br />87.5 percent as shown in table B. <br /> <br />44. Ouring the period October 1951 through March 1972 a total of <br /> <br />7,488 days, the reservoir was dry or operated on an outflow equal inflow <br /> <br />basis 2,316 days or 30.9 percent of the time. During periods of storage, <br /> <br />a total of 5,172 days or 69.1 percent of the time, the reservoir was <br /> <br />below elevation 3,810 feet a total of 3,339 days nnd above this elevation <br /> <br />1,833 days. <br /> <br />20 <br />