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'01243 November 19. 1993 Short-Term Adjustments to CRSM Projections Issue Western is examlnlng some of its past practices and assumptions used to develop long-range annual power projections for the CRSP and SLCA/IP power repayment study. One component of interest includes near-term adjustments to the Colorado River Simulation Model (CRSM) power projections. Background . Previous years' studies included near-term. 5-year adjustments to Reclamation's projections for CRSP energy and capacity to reflect impacts of recent drought years and starting condltions assumptions. The methodology used to apply short-term projections to the first five years of the study period was a simple linear interpolation. The endpoi nts cons i sted of the most recent projected generat ion fram Reclamation's Annual Operating Plan for the Study Year and the middle-envelope smoothed average CRSM projection for the slxth year. . The initial application of adjusting CRSM projections for annual generation. used in the FY 1992 Rate Adjustment. had been criticized by the Colorado River Energy Distributors Association (Ltr. Barrett. CREDA. to Greiner. 12-19-91). Western had supported application of this adjustment (PIF. 3-30-92) based on the concern that (a) the then-hydrologic data base used in the CRSM model ing did not yet contain several years (1989-91) of recent well-below average inflows. and (b) the assumed reservoir starting conditions (October 1990) were higher than what could be expected near-term. given the continued drawdown evident by October 1991. These limitations were then perceived to be technical deficiencies in the input data used in the model. In addition. based upon new information developed by Western through simplified reservoir routing between Lakes Powell and Mead under a range of inflow conditions. Western concluded that near-term projections for CRSP annual generation from the CRSM were indeed optimistic. The linear adjustment was then applied to .account for thi s deficiency. . In May 1993. at Western' s request. a speci a 1 60-month study was performed by Reclamation attempting to refine short-term generation projections. The study used the Annual Operating Plan features of the CRSM to manually simulate reservoir operations under specified condi t ions. Wi th the recurri ng assumpt i on of average i nfl ow. reservoi rs were operated to capture the effects of Biological Opinion compliance at flaming Gorge and other special release requirements at the Aspinall Unit. The annual results using this approach. when compared to the average annual energy projections from the earlier CRSM results. suggested significantly qreater annual generation from CRSP.