| OCR Text |
Show later for the other states of the Upper Basin. References to forecasts by federal and other agencies are also made in this Appendix. The Commission is authorized by Article VIII of the Upper Colorado River Basin Compact to make findings of fact and through cooperation with the Water Resources Branch of the U.S.G.S., it is in a position to do so in regard to water deliveries made at Lee Ferry. Reports received to-date show that 11,057,000 acre-feet of water passed Lee Ferry during the water year of 1950 and that 9,831,000 acre-feet passed this point during the water year of 1951. These reports also show the total deliveries of water during the two ten-year periods for the water years 1941 to 1950 and for 1942 to 1951, both inclusive, of 130,375,000 acre-feet and 124,138,000 acre-feet, respectively. The investigation of reservoir losses which was mentioned in the last annual report has been undertaken during the past year and a report on these studies to-date appears as Appendix G in this Third Annual Report. This Appendix on evaporation gives formulas for estimating the approximate losses from reservoirs in the Upper Basin at possible reservoir sites where no climatological data are available. The formulas depend only upon the average elevation of the water surface and the latitude at the proposed site. The standard error of these formulas is less than 3 inches or 5.5% of the average annual depth (55 inches) of evaporation for the 24 weather stations considered in this investigation. The actual amounts of evaporation vary from an average of 91.2 inches at Lake Mead to 22.5 inches at the highest elevation considered, 10,000 feet. At such high elevations, the maximum error may be as much as 5 inches, the estimates being too low by that amount. The report also includes a table showing the estimates of the evaporation reported for the Commission in a memorandum dated November 21, 1951. The table shows the probable increase in the evaporation for the combinations of reservoirs at the Desolation and Gray Canyon sites of 261,000 acre-feet over what would probably occur from the Echo Park and Gray Canyon sites. This indicates, as has been repeatedly stated, the increased loss that must be anticipated from any substitutions of other reservoirs for those proposed in the Colorado River Storage project and participating projects report of the Bureau of Reclamation. The combination of the Desolation and Dewey sites in place of Echo Park and Gray Canyon which has been recommended from certain quarters would give an increase of evaporation over that to be expected from Echo Park and Gray Canyon of 560,000 acre-feet. This is over 3i/2 times as great a loss as would occur from Echo Park and Gray Canyon combined. -10- |
