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Reservoir Operating Studies An important limitation imposed by the use of monthly hydrology is the inability to examine effects on peak flows and on flows during periods of rapid change. For example, an average July flow of 900 cfs might in reality be a flow of 2,000 cfs at the beginning of the month and 200 cfs at the end of the month. Water Demands Existing basin water uses are generally represented in the model through the use of gaged flow hydrology rather than virgin flow hydrology. Implicit in this method is the assumption that those historical water use patterns imbedded in the gaged hydrology will continue in the future as they have in the past, unaffected by any additional water development or management simulated explicitly in the basin model. Exceptions to this generality include major municipal and industrial uses relying on water ' rights junior to the Juniper Project rights and longstanding agricultural uses that, by virtue of late adjudication, have water right priorities that are junior to the 1954 Juniper Project rights. Depletions associated with these existing junior uses were explicitly represented in the model rather than implicitly represented by the gaged (depleted) hydrology in order to the evaluate the effect of the Juniper Project water rights on other basin demands and to estimate the project's contemplated draft. In the predecessor study, approximately 13,000 of of agricultural depletions with junior water rights were thus explicitly represented; these depletions were derived from data provided by Division 6 but did not include diversions with estimated annual depletions less than 5 of or reservoirs with estimated depletions of less than 700 af. In the present study the model was modified to include an additional 4,000 of of junior depletion attributable to these smaller agricultural uses. The resulting total of roughly 17,000 of includes all junior agricultural depletions estimated by Division 6. Three basic demand data sets were defined for use in the basin model, representing three levels of water demands. These demand levels were defined during the predecessor study as representative of current (1989) potential demands and demands associated with population and industrial growth projected for the years 2015 and 2040. Current Potential Demands The current potential demand level was defined by making certain adjustments to recently observed water diversions and depletions. These adjustments were of two general types: 1) adjustments to "level out" historical demands over the entire 53-year study period, and 2) adjustments to account for the fact that observed historical water deliveries do not completely describe water demands. The former adjustment is made in recognition of the fact ' that water demands in certain sectors, notably municipal and industrial, have grown and changed significantly over the 1930-82 study period. The second adjustment is made in recognition of the fact that, even under current development conditions, there is potential for increased water use due to climatic factors, greater utilization of generating capacity at power plants, repair of washed out headgates, etc. Accordingly, the current potential demand level reflects the maximum estimated water requirement associated with current basin development imposed uniformly upon the hydrology of the 1930-82 study period. Table 2-1 below summarizes the current (1989) observed and potential water demands in various sectors of the ' basin economy. 2-3