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<br />. <br /> <br />I--' <br />o <br />00 <br />~ <br /> <br />. <br /> <br />. <br /> <br />EVALUATIONS OF EXISTING SALINITY CONDITIONS (continued) <br /> <br />period occurr~ng at the present (197B) time. Tl1is is shown for eac~~ <br />station on Table E in Part VII. Adjustments to the historic flow that were <br />made to develop the present modified flow included: (1) adjustments for <br />the increase in depletion in 1~78 over that for years prior to 1976; (2) <br />removal of storage effects below large reservoirs by adding the historical <br />storage and subtracting storage releases to obtain unregulated flows at <br />each station; and (3) adjustments for historic evaporation as compared to <br />average present evaporation. The large reservoirs considered in these <br />adjustments were Flaming Gorge, Lake Powell, Wayne ~. Aspinall Unit Reser- <br />voirs, Navajo, and Fontenelle Reservoirs in the lIppeI' Basin, and Lake Head, <br />Lake Mohave, and Lake Havasu in the Lower Rasin. <br /> <br />Average present evaporation from the eRSt? Reservoirs plus Navajo and <br />Fontenelle Reservoirs was estimated to be 508,000 acre-feet (7lJl x 106m3) <br />per year. (Note: This is the latest evaporation estimate pending results <br />from additional invest igat ions being conducted.) This would ioc lUGe evalJo- <br />ration from Lake Powell of 460 000 acre-feet (;,7ll x 100m3); Flaming <br />Gorge, 50,000 acre-feet (6ll x 106m3); Wayne N. Aspinall unit Reservoirs, <br />10,00ll acre-feet (12 x 106m3); Navajo, 26,000 acre-feet (3L x 100m3); <br />and Fontenelle Reservoir, 22,000 acre-feet (27 x lO6m3). These figures <br />were chosen to represent present conditions rather than using the 19/8 his- <br />torical evaporation since a single year record could show an above-or-below <br />normal condition. Present evaporation of the Lower Basin reservoirs <br />was assumed the same as historical since these reservoirs have been oper- <br />ating for a number of years. <br /> <br />Historical flows since 1941 have been affected by the transmountain <br />diversions of the Colorado-Big Thompson Project, Duchesne Tunnel ot Provo <br />River Project, Roberts Tunnel of the city of Denver, and a number of small <br />in-basin developments in the Upper Basin. More recently the Independence <br />Pass expansion, Fryingpan-Arkansas, Collbran, Paonia, Sr.lith Fork, Silt, <br />Florida, Hammond, Bostwick Park, San Juan-Chama, Navajo Indian Irrigation, <br />Cheyenne-Laramie, Navajo M&I Contracts Projects, and Vernal Units of <br />Celltral Utah Project have come into operation. In addition water is used <br />by the Hayden-Craig Steam Powerl'lant, Four Corners Steam Powerplant, <br />Huntington Powerplant, Navajo Powerplant, San Juan Powerplant, exvansion of <br />Hogback Indian lands, and the municipalities and industries in Wyaning. In <br />the Lower Basin, corrections have been made for the Southel:n Nevada Water <br />Project, the Hetropolitan Water District diversion at Lake Havasu, the <br />Colorado River Indian Reservation, and the Palo Verde lrrigation District. <br />The depletions from all of the above projects have been extended back to <br />1941, frow the time they became operational, so that when increased deple- <br />tions on existing projects or new depletions on new projects Occur they can <br />be imposed directly on the present modified condition to show tile antici- <br />pated effect of all develo}.>ment on the river. In the near future several <br />projects om" under construction will become operational. The audition of <br />these new depletions will result in slight increases in dissolved-solids <br />concentrations under present modifi~d conditions. <br /> <br />45 <br />