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OD07S7 5. Other Alternatives · }'Jternative 6a: Insurance Pool. The methodology used in the analyses, together with the results and conclusions from this investigation are summarized in this report. Detailed analysis methodology, results and conclusions are presented in a series of eleven Technical Memoranda that are included in the Appendices. GENERAL RESULTS, CONCLUSIONS AND RECOMMENDATIONS The findings, conclusions and recommendations listed below concerning feasibility of the alternatives are the result of using a monthly hydrology model called StateMod and the C1 Data Set as agreed to by the Executive Committee at the start of the study process. It was realized that perspectives and model analysis might differ from the perspectives and model analysis of some Executive Committee members and the water conservancy districts, water suppliers and water users who may be affected by these alternatives. In reality, reservoir operators will not preemptively release water from their reservoir(s) unless one of two conditions exists: 1) the operator, based upon real time snow pack and runoff knowledge, determines that it is highly likely the reservoir will fill and spill or 2) the operator has access to an "insurance pool" of water in case a preemptive release results in the loss of water to the reservoir. The first condition is basically what occurs in the CROPS and cannot be counted as a new alternative. The second condition is the most promising alternative for meeting the 20,000 acre-foot goal through use of existing reservoirs. While these conclusions are somewhat different than a reader might deduct by solely reading the study, the study participants agreed that it was important, in furtherance of the commitments in the PBO, to list the following study results for documentation purposes: 1. Supplying 20,000 acre-feet to the 15-Mile Reach was not required every year. It was necessary to supply the 20,000 acre-feet in only six years (1975, 1978, 1979, 1980, 1985 and 1986) and possibly 1982 and 1991 for a total of eight years out of the 17 years during the 1975-91 study period. 2. Supplying the 20,000 acre-feet was not required during the very dry years of the study period. For example, releases were not required in 1977 or 1981. Further analysis indicates that supplying the 20,000 acre-feet would not have been required in 2001 and 2002. It is also important to recognize that there is a fundamental difference between what a monthly hydrology model calculates is possible and what reservoir operators will actually agree to do after dry years. For example, no reservoir operator would allow non-required reservoir releases in years following dry years - like 1978 or 1982 - until it was demonstrated that the reservoir would fill, regardless of the fact that the model indicates this type of release could be accomplished. The difference in the projected availability of releases and the reality of available releases is because the model has "perfect knowledge" on when the reservoir would refill - reservoir operators do not. Because the model indicates that supplying the 20,000 acre-feet in dry years is not required, it provides reservoir operators some comfort that firm yield would not be impacted. 1& P: \Data \ GEN\ CWCB\ 19665\Repon Phase 2\FinaIRepon9.03\Final_ CFOPS_Repon(9-03) .doc 2