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<br />'=:J <br />-, <br /> <br />~ to detennine if the river channel in the vicinity of the brid/(e has <br />N <br />~ materially changed and if these changes could be attributed to the <br /> <br />operation of John \Iartin Reservoir. A summary of the results of these <br /> <br />resurveys is presented in table 5. TIle greatest change since the <br /> <br />original survey in 1942 was a reduction in the opening of 1,202 square <br /> <br />feet as inUicateJ by the 1972 resurvey. An increase in the opening <br /> <br />occurred only during the period December 1945-Apri 1 1951. All the changes <br /> <br />to date are attributed to natural causes of the stream and not to the <br /> <br />effects of John flartin Reservoir. <br /> <br />27. Suspended sediment sampling. Computed resul ts of sediment <br /> <br />transport ,leterrnined from suspende<.l sediment sampling at the inflow and <br /> <br />outflow stations at John flartin Reservoir arc tahulated in table 6. Annual <br /> <br />suspended sediment loads for the inflow and outflow gaging stations are <br /> <br />presented in table 7. The total suspended sediment inflow to John flartin <br /> <br />Reservoir is presented in table 8. This includes the estimated intervening <br /> <br />sediment inflow hetween the two gages at Las Animas, Colorado, and the dam. <br /> <br />TIle figures in this table were used to compute the trap efficiency from <br /> <br />Octoher 1942 through March 1972. Suspended sediment sampling on a daily <br /> <br />basis was <.liscontinued at the inflow stations on 1 October 1962. TIle <br /> <br />present program is one of intennittent sampling by the U.S. GeOlogical <br /> <br />Survey. Dai ly samples are taken at the gage below the dam when re leases <br /> <br />are made from the reservoir. Sediment inflow to the reservoir for the <br /> <br />----._- ------ <br /> <br />period since October 1962 has been computed by correlating the inflow gage <br />.-- ...-m.'7- <br /> <br />charts at each station with sediment rating charts derived from the period <br /> <br />12 <br />