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<br />. <br /> <br />IX. SUPPORTING DATA FOR POWER REPAYMENT STUDIES <br /> <br />A. CRSP Power Resources and Power Sales. CRSP hydroelectric <br />capacity and energy resources are largely dependent on climatic conditions <br />which affect both the supply and use of water. In addition, power <br />operations must be conducted within the limitations of the water statutes, <br />treaties and compacts governing the use of Colorado River water. Figure g <br />shows the Colorado River flow at Lee Ferry, Arizona, for the period 1896 <br />through 1981. In the 18 years since CRSP generation was initiated in <br />November 1963, the flows have exceeded the 1896-1981 average virgin flow in <br />7 years, equaled the average 1 year, and in 10 years the flows were less <br />than the average. <br /> <br />1. HYdroloaica1 Basis for Estimating CRSP Generated Energy. <br />Actual CRSP generat10n ata were used through FY 1981. The hydrological <br />analysis used for projections of CRSP-generated energy after FY 1981 was <br />based on runoff and depletion records for the Colorado River drainage system <br />above each of the reservoir sites for the period 1906 through 1980. These <br />records were modified by subtracting estimated future depletions as shown on <br />Table 3. The September 1981 depletion schedule as prepared by the Bureau of <br />Reclamation was used as a basis for estimating future depletions except that <br />the depletions for the five participating projects whose status is <br />uncertain, were assumed to be delayed from FY 2010 to FY 2031. The assumed <br />delay of the projects is discussed on pages 3 and 45. The study assumed <br />that there would be 5.8 million acre feet of depletions in the Upper <br />Colorado River Basin by FY 2040, and includes 157,000 acre feet of <br />unidentified depletions. Using the modified records, fifteen 75-year <br />sequences of operation were run. In the first sequence, the water supply <br />for 1982 was assumed to be equal to that of 1906, as adjusted for <br />depletions. In the second sequence, the water supply for 1982 was assumed <br />to be equal to that of the year 1911 as adjusted. The other sequences were <br />run similarly using 5-year intervals to determine the water supply for 1982 <br />until in the fifteenth sequence, the water supply for 1982 was assumed equal <br />to that of 1976, as adjusted. <br /> <br />The averages of the generation computed for each sequence of the fifteen <br />sequences for each future year represent a reasonable estimate of the future <br />average CRSP generated energy. <br /> <br />2. Energy. The jagged curve of Figure 10 represent the <br />estimated annual energy generation at load, assuming 7 percent transmission <br />losses. The dotted curve represents a smoothed average of the generation. <br />The annual data from this smoothed curve were used in the power repayment <br />studies. Generation increases gradually through 1993, the year when the <br />major part of the Central Utah Project (CUP) energy generation is expected <br />to come on the line. Only the energy in excess of project needs was <br />included in the CUP generation. The general trend is downward after 1993 <br />due to the anticipated upstream water depletions. <br /> <br />Table 4 is a tabulation showing the estimated total CRSP energy generation, <br />total energy sales, including committed CRSP firm sales, requirements for <br />Rio Grande Project (RGP) firming, project pumping and salinity control <br />requirements, and purchases. All the quantities are at load and assume 7 <br />percent transmission losses. <br /> <br />22 <br />