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<br />v. Shortal!eDetennination Criteria <br />The Six States believe that considering current reservoir conditions and with prudent <br />system management, the Secretary of the Interior should not have to declare a shortage condition <br />for many years. Even with this recognition, the Six States believe that the establishment of <br />shortage criteria that work in conjunction with the interim criteria is valuable for two primary <br />reasons. First, the Arizona Water Bank has been created within Arizona primarily to store water <br />underground over the next twenty years to mitigate the effects of future shortages to Arizona <br />municipal water users, Shortage criteria are critical for Water Bank planning. The volumes of <br />water that Arizona will withdraw as either basic apportionment or surplus apportionment over the <br />next ten to twenty years is highly dependent on the need for water banking that will be used as <br />shortage protection, Secondly, shortage criteria are needed to be able to identify any negative <br />impacts created by the implementation of the temporary surplus criteria All Six States, and <br />especially Arizona and Nevada, want to be able to identify when the release of water to California <br />from either the partial or full M&I surplus tiers, causes an increased risk of shortage. This <br />analysis can only be perfonned if the shortage criteria are known. <br />The Bureau of Reclamation has been studying options for shortage criteria for a number of <br />years. The framework for most of these strategies is to declare limited cutbacks well in advance <br />of the point where those levels are critical. The most junior Lower Division water user, the <br />Central Arizona Project, bears the burden of most of the delivery reduction. The timing of the <br />reduction is based on the use of computer models to simulate reservoir operations, The model <br />study focuses on the statistical probability of reservoir levels dropping below a critical "protect" <br />leveL The Six States endorse this framework and propose to adopt the protect level in Lake <br />Mead of elevation 1050 (7.471 maf content) which is the elevation of the intake structure for the <br />Southern Nevada Water Project. The Bureau of Reclamation has named this shortage strategy <br />"80P1050." In accordance with the Bureau's studies, this level would not be guaranteed but the <br />risk of drawing down to below that level would be limited to 20%, When the model studies <br />indicate that the reservoir level is in jeopardy, a first tier shortage would be declared which would <br />reduce Arizona's consumptive use by the CAP and other similar priority users to no more than <br />1,000,000 acre feet (about a 500,000 af reduction). Nevada would also share in shortages, but to <br /> <br />11 <br /> <br />. <br /> <br />. <br /> <br />. <br /> <br />. <br />