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<br />.~ <br /> <br />N <br />QO <br />1'\) <br />~ <br /> <br />only 90 c.f.s. daily. During this 5 year period there were only 3 days <br /> <br />when daily flows exceeded 1,000 c.f.s. This, with erosion in the reservoir <br /> <br />area, made it possible for the river to transport sediment into the reach <br /> <br />but flows were never sufficient to scour or remove. deposited sediment. In <br /> <br />the future high flows will scour the reach to the pattern established <br /> <br />between the original survey and the 1966 survey. <br /> <br />30. Aerial topographic survey results. TIlC aerial survey was made <br /> <br />when the reservoir was dry and topograph at 5-foot contour intervals was <br /> <br />obtained to elevation 3,8!;5.0 feet and a 1" = 400' horizontal scale. The <br /> <br />top elevation was chosen because it was close to the maximum pool elevation <br /> <br />of 3,856.16 feet observed on 25 August 1965. <br /> <br />31. TIle survey indicated that 12,453 acre-feet of sediment were <br /> <br />deposited in the reservoir in the 1.9 years from September 1966 to August <br /> <br />1968. Water inflow. for the same pcriod was 276,451 acre-feet. The annual <br /> <br />average for the 1.9 year period were 145,500 acre-feet of water inflow and <br /> <br />6,554 acre-feet of sediment deposition. <br /> <br />ANALYSIS OF SEDIMENTATION <br /> <br />32. Volume of sediment in John Martin Reservoir. The volume of <br /> <br />sediment deposited in John Martin Reservoir was 80,449 acre-feet for the <br /> <br />30 years of operation from April 1942 through March 1972. The average <br /> <br />annual storage reduction for this period was 2,682 acre-feet per year. <br /> <br />During the period September 1966 through March 1972 (5.6 years) there was <br /> <br />a total storage reduction of 9.795 acre-feet. During the period September <br /> <br />1966 to August 1968 (1.9 years) there was a storage reduction of 12,453 <br />Cb:'lOo I'\f l'le,:,( <br />/ <br /> <br />14 <br />