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<br />. . <br />, . <br /> <br />The irrigation depletions for the Navajo Nation's irrigation projects are water right <br />depletion amounts provided by the Settlement Agreement. Boththi.s hydrologic <br />investigation and the 1988 Hydrologic Determination assume use of the :full depletion <br />amount for the NIIP. This is a conservative assumption because the total NIJP depletion <br />right is not expected to be fully utilized under nonnal farm management practices. . The <br />revised depletions schedule does not include New Mexico's allocation of shared CRSP <br />reservoir evaporation. The revised New Mexico depletions schedule shows a total <br />anticipated depletion of 642,000 af per year, on average, for uses in New Mexico under <br />2060 development conditions. This represents an increase in New Mexico's total Upper <br />Basin depletion, excluding shared CRSP reservoir evaporation, of 23,000 af per year, or <br />about 0.02 mafper year, as compared to the January 2000 depletions schedules. <br /> <br />v. Probabilities of Calls to Curtail Upper Basin Uses <br /> <br />The 1988 Hydrologic Determination included. . a probabilistic risk analysis of <br />administrative calls to curtail Upper Basin uses that indicated that: (1) such calls would <br />occur rarely at an Upper Basin demand level of 6.1 maf per year, though their effects <br />could have significant impact to the Upper Basin; and (2) the frequency and magnitude of <br />such calls would diminish rapidly below this demand level. The risk analysis was made <br />using the CRSS model. It is not necessary for this investigation to duplicate such a risk <br />analysis. <br /> <br />The computations of shortage in this current investigation give conservatively large <br />estimates of annual shortages at Lee Ferry and do not fully reflect all factors, including <br />physical shortages in the Upper Basin, that might contribute or relate to a shortage <br />condition at any given time. While this investigation uses a 2060 reservoir storage <br />sedimentation condition for Lake Powell, a risk analysis should vary the. storage <br />development and sedimentation conditions over time. In addition, it will take decades to <br />develop the Upper Basin allocation. Therefore, risk of shortage is reduced within a 2060 <br />planning horizon. Even using the CRSS model, computed shortages would not <br />necessarily equate to administrative calls to curtail Upper Basin uses. <br /> <br />VI. Phvsical Availability of Water from Navaio Reservoir <br /> <br />The Bureau of Reclamation using a detailed hydrologic model for the San Juan River <br />Basin has evaluated the physical availability of water from Navajo Reservoir and the San <br />Juan River for the Navajo-Gallup Water Supply Project, taking into account, among other <br />things, the habitat needs of San Juan River populations of fish species listed as <br />endangered under the Endangered Species Act. The physical water supply analysis <br />contained in the Biological Assessment, Navajo.-Gallup Water Supply Project, dated <br />August 16, 2005, indicates that sufficient water is likely to be available from the Navajo <br />Reservoir water supply for the Navajo Nation's uses under the project. Although the <br />depletions for individual uses in New Mexico that were used in the Biological <br />Assessment differ slightly from those in New Mexico's May 2006 revised depletions <br /> <br />6 <br />