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I I I I I I I I I I I I I I I I I I I Demand Shortfall Table 1 outlines the historical water use (i.e., demands) on the part of different LA WMA user groups during normal and dry years. LA WMA's available water supplies will not always be sufficient to meet these demand levels. In years where available water supplies are relatively low, the amount of water some users are allowed to pump (i.e" are allocated) will be less than the amount they desire (i.e., demand). The demand shortfall imposed by an allocation method on a particular user group is defined here. Demand Shortfall is defmed as the percent reduction in a group's water allocation relative to what that group needs (i.e., demands or desires) in that year. The amonnt of water the group desires is based on historical water demand use patterns. Demand shortfall is expressed as a percentage reduction and is calculated as: (desired pumping this year) - (allowed pumping this year) (desired pumping this year) x 100 Table I shows that, in a dry year, supplemental users demand 74,949 af of pumping. Ifin a dry year supplemental users are only allowed to pump 58,500 af, these users have a demand shortfall 01'21.95%; [(74,949 - 58,500)/74,949] x 100 = 22%. Demand shortfall is a measure of how much the user must cut back his pumping in the current year as measured against what he desires in the current year. In some cases demand shortfall may be less than zero. A negative sign on the demand shortfall would indicate a user is allowed to pump more than they desire for their own use. In situations like this, the user may desire to lease their surplus rights to another user. Demand shortfall can also be calculated by using replacement water demand instead of pumping demand. Using the above example, in a dry year supplemental users demand 14,098 af of replacement water (74,949 af of pumping x 0.3 x 0.627). If in a dry year these users are allowed to pump 58,500 af of water, this allowed pumping level converts to 11,004 af of allowed replacement water (58,000 x 0.3 x 0.627). Using 14,098 of the amount of water desired and 11,004 of the amount of water allowed, we obtain a demand shortfall of22%; that is, [(14,098-11,004)/14,098] x 100 = 22%. Curtailment Similar to demand shortfall, the curtaihnent measure is another indication of "how much a user must cut back." Different from demand shortfall, however, curtaihnent indicates how much the user must cut back as measured against what he has historically been allocated in a normal year. EnWater Resource Consultants September 5, 1997 Final Report 19