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. 0761 . . TABIE ~ lRINIDAD RESERVOIR FLOOD CONTROL STORAGE REQUIREMENTS Estimated Total Flow : Flood Control Capacity Runoff Periods Past Dam Site : Required (Inclusive Dates) Inches of - Inches of : Acre-Feet Runoff Acre-Feet Runoff Sep 28 -Oct 2, 1904 h3,100 1.16 24,000 0.64 Apr 19-29, 1942 64,300 1.73 16,900 0.45 Standard Pro j. Flood 57,900 1.56 46,700 1.25 43. kEigatl-on storage. - The capacity allocated to irrigation storage was determined from a study conducted by the United States Bureau of Reclamation. This study ut~lized the water year period 1925- 1949. The recorded flows at the Trinj,dad gage were used without adjust- ment, as tte available flow at the Trinidad dam site. The assumption was made in the monthly operation study that the reservoir was depleted by a 50-year sediment reserve, amounting to 26,000 acre-feet. Evapora- tion losses were computed on that basis. The selected irrigation storage available in the Trinidad Reservoir for the study was 55,000 acre-feet. In the reservoir operation study for water supply, all stored .vater in excess of 55,000 acre-feet was spilled and considered as flood flows. Also, the study was predicated on the assumption that only the presently irrigated lands which amount to 19,500 acres would be supplied. Releases were made to meet the irrigation demands and in addition a minimum flow of five cubic feet per second was released during the winter months. Based on this study, the Bureau of Reclamation determined that 55,000 acre-feet should be allocated for the storage of irrigation water in the Tri nidad Reservoir, assuming that the project would ultin~tely be developed for the five conditions of operation as described in appendix D. It is esti- mated that this amount of storage would improve the effective irrigation 34 APPENDIX B .