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<br />~ <br /> <br />r..:. <br />o.J <br />CJt <br />-.t <br /> <br />releases exceeded inflows to the reservoir and the water surface ele- <br />vation at the end of the Water Year was 3,834.23. <br /> <br />14. In~ow and out~ow. The monthly inflow and outflow in acre- <br />feet for John Martin Reservoir for Water Years 1943 through 1966 are <br />shown in table 2. These data were taken from the daily operation <br />reports. The total monthly flows past the two inflow gaging stations, <br />Arkansas and Purgatoire Rivers at Las Animas, for the period 1943 <br />through 1966 are shown in table 6, The reservoir inflow obtained <br />from the daily operation reports and the reservoir inflow obtained <br />from the flow passing the inflow stations do not agree for the same <br />periods for several reasons. There is a small inflow below the in- <br />flow gages from springs, arroyos, and one ephemeral tributary. In <br />addition, the ungaged area frequently contributes flow from seepage <br />and wasteways of irrigation canals. There are losses due to.evapo- <br />transpiration and absorption by the sediment beds. When irrigation <br />storage has been exhausted and the reservoir becomes dry, evaporation <br />occurs from the wet deposits, and returns to the low-flow channel by <br />seepage are small. <br /> <br />15. Because of the ungaged inflows, it would be difficult to <br />accurately determine the reservolr losses. The net effect of the <br />ungaged inflow and reservoir losses is the difference between the <br />inflow and outflow figures shown in table 2. This table shows the <br />average annual inflow to the reservoir for the period 1943 through <br />1966 to be 229,544 acre-feet and the outflow for the period to be <br />205,548 acre-feeL When adjusted for storage, there would be a net <br />loss of 15,698 acre-feet annually for the period of operation. <br /> <br />16. R6Bervoir sediment range survey. The general plan of the <br />reservoir area showing the location of sediment ranges is shown on <br />plate 3. The field work for the 1966 resurvey was completed in <br />October. Submerged parts of 16 sediment ranges were resurveyed by <br />sonic sounder below elevation 3,831. Parts of the ranges above the <br />water or in shallow water were surveyed by conventional land methods. <br />The survey extended to the nearest monument above elevation 3,856, <br />which is approximately the highest elevation the pool has been since <br />the 1962 resurvey. The resurvey included ranges from the dam to and <br />including Range 17 on the Arkansas River, Range 22 on the Purgatoire <br />River, Range 32 on Rule Creek, and Range 10 on Gageby Creek. <br /> <br />17. Degradation ranges beZow John Martin Dam. There are 13 <br />monumented degradation ranges between the darn and Lamar, Colorado,. <br />a distance of 23 miles. These ranges are a part of the sediment <br />observation program for the John Martin Reservoir project and were <br />established to measure changes below the darn attributable to operation. <br />of the project. These ranges are resurveyed only when substantial <br />changes are apparent in the reach. They were resurveyed in 1944, <br />twice in 1945, 1951, 1962, and 1966. Land survey methods were used <br />to determine the profiles along each range. The amount of channel <br /> <br />5 <br />