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<br />I: .~~ <br /> <br />including physical shortages in the Upper Basin, that might contribute or relate to a <br />shortage condition at any given time. The computed shortages in this investigation do <br />not equate to administrative calls to curtail Upper Basin uses. <br /> <br />D. Comparison to 1988 Hvdrologic Determination <br /> <br />The 1988 Hydrologic Determination concluded that the total Upper Basin yield, <br />including CRSP reservoir evaporation, is at least 6.0 maf per year for the 1953-1977 <br />critical period hydrology with a 6 percent allowable overall shortage for the period. <br />Under the conditions assumed in the current investigation, the shared CRSP evaporation <br />varies with CRSP storage assumptions and storage levels. Assuming an average annual <br />Upper Basin use of 5.79 maf, an annual LoweT Basin delivery of 8.25 maf and <br />maintenance of the power pools, the shared CRS:P evaporation would range from an <br />average of about 0.25 maf per year over the worst 25-year period of reservoir storage <br />draw down (1953-1977) to an average of about 0.49 maf per year over the period of <br />record used in the analysis (1906-2000). Thus, the total Upper Basin depletion, including <br />both Upper Basin uses and CRSP reservoir evaporation, would average about 6.04 maf <br />per year or more over any period of 25 consecutive years. The total Upper Basin <br />depletion amount for this scenario for the 1953-1977 period is comparable to the total <br />Upper Basin depletion of 6.0 maf per year determined to be available for the period by <br />the 1988 Hydrologic Determination. The difference is due to the revisions made to the <br />CRSS natural flows for 1971-1980. If the minimum power pools are used, the shared <br />CRSP reservoir evaporation is reduced due to increased reservoir storage draw downs. <br /> <br />N. WaterUseProiections <br /> <br />A. UpDer Basin <br /> <br />The Upper Colorado River Commission last approved depletions schedules for the Upper <br />Division States for planning purposes in 1999. The depletions schedules, dated January <br />2000, project that the total Upper Basin use exclusive of shared CRSP reservoir <br />evaporation will average about 5.37 maf per year under 2060 development conditions. <br />Unless additional Upper Basin water development occurs by 2060 as compared to the <br />January 2000 depletions schedules, the Upper Basin use may average less than about 5.40 <br />maf per year from now through 2060. The time required to develop the Upper Basin <br />allocation reduces risk of shortage within the 2060 planning horizon. <br /> <br />B. State of New Mexico <br /> <br />The New Mexico Interstate Stream Commission for use in this investigation provided to <br />the Bureau of Reclamation a preliminary revised schedule of anticipated depletions <br />through 2060 from the Upper Basin in New Mexico dated May 2006 (see Appendix B). <br />The revised depletions schedule includes irrigation depletions calculated using the SCS <br />modified Blaney-Criddle method with SCS effective precipitation so that demands and <br />supply for this hydrologic investigation are evaluated using consistent methodologies. <br /> <br />5 <br />