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<br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />ou2505 <br /> <br />make the projected period similar to the historic period in terms of other water uses. <br /> <br />Figure E23 shows how the projected 120,000 non-flood monthly release volumes for Hoover <br />Dam are distributed as percent of values within 100,000 acre-feet increments. For example <br />9 percent of the values were in the range of 800,000 acre-feet, plus or minus 50,000 <br />acre-feet. . ' <br /> <br />Figure E24 compares the average and range of mean monthly flow depths below Hoover <br />Dam for the past 15 years versus the next 15 years. Flow depth is computed using the <br />discharge-elevation rating for the gaging station located about 0.5 miles below Hoover Dam. <br />Again, the average and range in flow depth is similar for the two periods for the reasons <br />given above. <br /> <br />Figure E25 shows how the projected 120,000 non-flood mean monthly flow depths below <br />Hoover Dam are distributed as percent of values within 0.5 feet increments. For example <br />about 9 percent of the flow depths were in the range of 12 feet, plus or minus 0.25 feet. <br /> <br />Figure E26 compares end of year Lake Mead elevation for the past 15 years with the <br />projected next 15 years. The projected period has lines showing how the projected elevations <br />were ranked in each year. For example in the year 2000, the minimum of the 1000 end of <br />year elevations was 1135 feet, the lowest 5 percent or the 50th of 1000 ranked elevations was <br />1167 feet, and the maximum, 95 percent, and 75 percent ranked elevations all showed Lake <br />Mead storage at the upper maximum elevation for flood control space required for the end of <br />year. <br /> <br />Figure E27 shows the cumulative probability distribution of the 15,000 end of year Lake <br />Mead elevations projected for the next 15 years. It shows that for the next 15 years, the <br />probability of Lake Mead being full is 0.34. There is a .99 probability that Lake Mead will <br />be above elevation 1130 feet over the next 15 years. <br /> <br />Comparison of Projected vs Historical Operations for Lake Mohave/Davis Dam <br /> <br />Figure E28 compares the average, maximum, and minimum monthly release as a monthly <br />volume in units of 1000 acre-feet for Davis Dam. for non-flood control years for the past <br />15 years versus the projected next 15 years. The overall comparison shows that within the <br />accuracy of the simulation model, the projected 15 year period is very similar to the past <br />15 year period in both range in monthly release and average release for the two periods. <br />This should be expected given the high variability of both water use and hydrologic gains <br />below Davis Dam including the Gila and Bill Williams Rivers of the past 15 years. Also the <br />lack of need for any appreciable surplus uses or shorted uses make the projected period <br />similar to the historic period in terms of water use. <br /> <br />Figure E29 shows how the projected 120,000 non-flood monthly release volumes for Davis <br />Dam are distributed as percent of values within 100,000 acre-feet increments. For example <br /> <br />Appendix E - 7 <br />