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<br />Under full development the total of uses and losses in the lower basin exceed the total of the <br />intervening flows plus 8.23 maf. Rather than restrict the amount of full dependable <br />development, the lower basin relies upon the application of shortage provisions which assures <br />that depletions will be reduced during times of long-term drought. Under full development, <br />8.23 maf plus intervening flows can be balanced when CAP has restric:ted diversion. <br /> <br />The studies also highlighted how the strategies developed to date were more or less arbitrary. <br />That the evaluation of a strategy has been based on the end results the strategy would achieve <br />and not on whether there was technical merit to the strategy. As forecasted use was <br />changed, or as initial reservoir starting conditions was changed, the effects of using a <br />particular strategy changed, as did the evaluation of the strategy. Recognizing how <br />unpredictable the future conditions are, if there is no technical rationale for a strategy, there <br />is no foundation that maintains the strategy over time and change. <br /> <br />There appears to be no technical, or legal basis for considering the determination of <br />surpluses at 70 percent capacity, or 80 percent capacity, or 90 percent capacity. Nor is there <br />a basis for varying the surplus threshold capacity over time, from 70 percent to 90 percent, <br />or basing the variation on the development of lower basin use, or total basin use. There may <br />be some logic for determining surplus in order to maintain sufficient storage space to assure <br />that in the current year a spill would be avoided in 70 percent of the years of known <br />hydrology, or 80 percent of the years of known hydrology. However such a strategy does <br />not consider potential future effects and under full development, drawing Lake Mead down <br />into a shortage determination may occur as much as about 40 percent of the years. <br /> <br />Reclamation's Appendix A of the May 1990 Review of Water Supply Shortage Criteria and <br />Reservoir Sizing Criteria states that while no formal documentation on irrigation water <br />shortage criteria was found, "a longstanding "guideline" allows a shortage of 50 percent of <br />the annual demand in the most critical period, and a cumulative shortage of 100 percent of <br />the annual demand in a consecutive 10-year period." In the lower basin, under a shortage <br />determination CAP agriculture would be shorted 100 percent each year the determination was <br />made. <br /> <br />The term "602(a) storage" refers to the quantity of water required to be in storage in the <br />Upper Division so as to assure future deliveries to the Lower Division without impairing <br />annual consumptive uses in the Uppe~ Division. Water not required to be stored for this <br />purpose is released from Lake Powell to either maintain, as nearly as practicable, active <br />storage in Lake Mead equal to the active storage in Lake Powell, or to avoid anticipated <br />spills from Lake Powell. For long range planning purposes 602(a) is applied using the <br />critical period of record as the controlling hydrograph. <br /> <br />By applying similar methodology to the lower basin a critical storage provision could be <br />developed which would define that amount of storage required for the Secretary of the <br />Interior to satisfy the annual consumptive use of the Lower Divisions States through the <br /> <br />19 <br />