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for power purposes shall for irrigat ion purposes, 564, not deplete or interfere with the use thereof " Act of August 9, 1937, Ch. 570, 50 Stat. 1. Hydrological Basis for Estimating Project-Generatea Energy. Figure 5 shows the historical inflow to Elephant Butte Reservoir for 1916, the year storage began in the reservoir, and for each year there- after through 1980. This period contains a wide range of hydrologic con- ditions varying from critical dry years to wet years, with an average annual inflow of 813,000 acre-feet. The annual inflow from 1916 through 1940, before the powerp 1 ant was placed in serv ice, averaged 1,021,000 acre-feet. Since then (1941 through 1980), the average annual inflow was only 683,000 acre-feet. The general downward trend is illustrated by the line labelled "Cumulative Average Annual Inflow," The 1941 through 1980 generation averaged 60,106,000 kWh. 8ecause of the existence of actual generating data for the 40 year period 1941 through 1980, it would not be unreasonable to use that period as a basis for projected future generation. However, it appears that a more reasonable approach would be to use the entire historical period of 1916 through 1980 as a basis for projected future generation. In the absence of a reliable year-by-year hypothetical generation study based on the historical 1916 through 1980 inflow to Elephant Butte Reservoir and upstream depletions, the decision was made that the generation in the median inflow year of the 1916 through 1980 period would be used as the estimated projected future annual generation. The median inflow year was 1966, 2. Project-Generated Energy. The est imated future annual energy generation used in the repayment studies was 67,786,000 kWh, which was the actual generation in the year 1966. This amount was broken down in the studies to a summer component of 53,304,000 kWh and a winter compon- ent of 14,482,000 kWh. The wi nter component was est imated as exp 1 a ined in the following paragraph, and the summer component was the annual gen- eration less the winter component. In most of the years since 1941 When generat ion started at Elephant Butte, the plant has been operated during the months of February and I~arch, However, the generation during the other winter months of October through January has been, very little since 1947. In view of the foregoing, it has been assumed for the present studies that the future generation in February and March would be the average of the generat ion for those months in the 1941 through 1980 period and the future genera- tion for October through January would 'be the average of the generat ion for those months in the 1948 through 1980 period, as follows: Actual 1941 through 1980 average generation for February and March 11 ,329 ,000 kWh Actual 1948 through 1980 average generation for October through January 3,153,000 kWh Total estimated winter season generation in future years 14,482,000 kWh 19 1" " () ,! tL.. ~