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<br />by strategy since the strategies affect water supply downstream from <br />Lake Powell only. <br /> <br />g. As shown in table 6, appendix A, a balance in storage is generally <br />maintained between the Upper and Lower Basins for the various hydro- <br />logic traces and depletion schedules. <br /> <br />Results and Conclusions <br /> <br />From a technical standpoint, alternative strategies exist for <br />operating the Colorado River reservoir system to provide greater <br />benefits with only minimal risks. Alternative operating strategies <br />allow additional water to be released for use by Metropolitan Water <br />District (MWD) and the Central Arizona Project (CAP) and for addi- <br />tional power generation, while maintaining a conservation pODl large <br />enough to provide adequate water supplies for both the Upper and Lower <br />Colorado River Basin water users throughout the study period. <br /> <br />An independent analysis of potential operating strategies has been <br />done by a team at Colorado State University Civil Engineering <br />Department. The results of that work confirm that the range of <br />management strategies considered in this study generally provided <br />the most fa~orable results in terms of moderate reservoir releases <br />and increased power generation over a wide variety of hydrologic <br />conditions. <br /> <br />Figure 2 summarizes the approximate magnitude of change in various <br />parameters of interest ranging from the base case to the high <br />assurance operating strategy based on mean historic hydrology and the <br />USBR depletion level assumptions. For instance, MWD would receive <br />increasingly larger amounts of water annually as the assurance le~el <br />increases, reaching a high of 240,000 acre-feet per year at the <br />highest assurance operating strategy. On the other hand, the addi- <br />tional surplus releases could decrease total system storage by about <br />6 million acre-feet at the end the study periOd under the highest <br />assurance operating strategy (O.99) but only by about 2 million <br />acre-feet under the 0.90 operating strategy. <br /> <br />Figures 3 and 4 show how sensitive some of the operational parameters <br />are to the effects of hydrology. These graphs show the changes that <br />would result by using a high (0.99) assurance level when compared to <br />the base case. The deliveries to MWD are increased by more than <br />225,000 acre-feet per year in the wet and mean scenarios, and nearly <br />140,000 acre-feet in the dry scenario; thus, are not particularly sen- <br />sitive to imposed hydrology. <br /> <br />In contrast, deli~eries to Mexico and total system storage levels <br />(figure 4) are sensitive to hydrologic scenarios. Mexico would <br /> <br />9 <br />