Laserfiche WebLink
<br />.. c~~lative impacts o.f water diversion or removal on habitat <br />are much less dramatIc and not as obvious as the more sudden <br />____ chan~ created by a lar~e_danL--llnd----I'eS-e-t'V-O-it'-.----9~~ITe--efld--- <br />result is si~ilar i~ relation to the loss of ~abitat needed <br />for the contInued eXIstence of the listed fish species. <br /> <br />The natural flow of the Upper Colorado River (as re- <br />corded at Lee Ferry) has averaged slightly less than 18 x <br />109 m3 [15 mi llion acre feet (MAF)] annually over the past <br />80 years. Annual flows have ranged from a low of 7 X 109 3 <br />(6 MAF) to a high of 30 x 10? m3 (24 MAF). Approximately ~5 <br />percent of the. natural flow IS presently being depleted from <br />t?e up~er basIn. . The consumptive use in the upper basin <br />(IncludIng reserVOlr evaporation) is approximately 5 x 109 <br />m3 (4 MAF) [14]. Ta~le I, from Harris et ale [14], shows <br />the percentage of est Imated future remaining flows as a re- <br />sult of water depletions in the upper basin. <br /> <br />Table 1. <br /> <br />Estimated future flows as a percentage of present <br />development in the upper basin [14J. <br /> <br />River Basin <br /> <br />Upper Green River <br />(above Flaming Gorge) <br />Yampa River <br />'Duchesne River <br />-, White River <br /> <br />l "l. <br /> <br />Total Green River <br />(above Green River, UT) <br /> <br />~Upper Mainstem (Colorado <br />River above Cameo) <br />Gunnison River <br />Dolores River <br /> <br />- s <br /> <br />) - IJ <br /> <br />Total Colorado River <br />(above Cisco, UT) <br /> <br />=~--\ <br />r - 7) Upper San Juan River <br />- (above Navajo Darn) <br /> <br />Total San Juan River <br />(above Bluff, UT) <br /> <br />3- i' TOTAL COLORADO RIVER <br />(above Lee Ferry, AZ) <br /> <br />? <br />,:7S~\ <br /> <br />.... ~~J <br />///1 <br />I~) Qy 3) i) <br /> <br />L <br /> <br />Natural <br />Flow 1980 1990 2000 2010 2030 <br /> <br />100 78 <br /> <br />74 <br /> <br />71 <br /> <br />67 <br /> <br />62 <br /> <br />100 99 <br />100 37 <br />100 100 <br /> <br />98 <br />37 <br />79 <br /> <br />79 <br /> <br />95 <br />29 <br />76 <br /> <br />75 <br /> <br />93 <br />29 <br />74 <br /> <br />73 <br /> <br />93 <br />29 <br />74 <br /> <br />71 <br /> <br />100 <br /> <br />85 <br /> <br />100 <br /> <br />46 <br /> <br />42 <br /> <br />38 <br /> <br />36 <br /> <br />36 <br /> <br />100 <br />100 <br /> <br />100 <br /> <br />100 <br />100 <br /> <br />85 <br /> <br />99 <br />89 <br /> <br />79 <br /> <br />99 <br />86 <br /> <br />75 <br /> <br />99 <br />86 <br /> <br />73 <br /> <br />99 <br />86 <br /> <br />71 <br /> <br />100 <br /> <br />89 <br /> <br />89 <br /> <br />89 <br /> <br />89 <br /> <br />89 <br /> <br />100 <br /> <br />82 <br /> <br />69 <br /> <br />67 <br /> <br />70 <br /> <br />70 <br /> <br />100 <br /> <br />75 <br /> <br />67 <br /> <br />64 <br /> <br />64 <br /> <br />61 <br /> <br />~':t;) <br />."., <br />Go <br /> <br />,,!~, <br />54lp:) <br />1'1 <br /> <br />'"'Il"'C <br /> <br />It is expected that the projected water use in the upper <br />b~,,~j.n_will increase to 6.0 x 109 m3 (4.9 MAF) by 1990, <br />6.7 x 109 m3 (5.4 MAF) by 2000, and to 7.2 x 109 ;:3--(5.8 <br />MAF) by 2030, while the average annual flow at Lee Ferry <br />will decrease from 12 x 109 m3 CIO MAF) at the present to <br />11 x 109 m3 (9.1 MAF) in 1990,11 x 109 m3 (8.6 MAF) in <br />2000, and 10 x 109 m3 (8.2 MAF) by the year 2030 [14]. Table <br />I highlights areas within the upper basin where future <br />demands for water will be the greatest. It may be more <br />prudent to pinpoint areas for recovery of the endangered <br />species based upon the projected outlook for water demands. <br />Certain areas may be more valuable to protect than others, <br />such as those areas which most nearly maintain pristine <br />flows. This would enhance the prospects of the coexistence <br />between energy development and the survival of endangered <br />fish in the upper basin. <br /> <br />Almost 15% [0.64 x 109 m3 (0.52 MAF)] of the total" <br />water depletion [4.8 x 109 m3 (3.9 MAF)] from the upper <br />basin in 1980 was attributed to reservoir evaporation [15]. <br />As noted earlier, there are over 20 other dams and reservoirs <br />which could be built and be in operation by the year 2000. <br />This could mean that the total water depletion in the upper <br />basin from reservoir evaporation might exceed 1.2 x 109 m3 <br />(1 MAF) within the next 20 years. The estimated total water <br />depletion from the upper basin by the year 2000 is approxi- <br />mately 6.2 x 109 m3 (5 MAF) [15], therefore almost 20% of <br />the total water depletion from the upper basin by the year <br />2000 could be a result of reservoir evaporation. <br /> <br />CHANGES IN FUTURE WATER USE <br />PATTERNS <br /> <br />Table II shows the future change in water use in the <br />upper basin based upon information presented by. Bishop and <br /> <br />Table II. Future change In water use in the Upper Colorado <br />River Basin. <br /> <br />Water Use <br /> <br />19731 <br /> <br />1980-2000 <br /> <br />Irrigation <br />Urban <br />Energy Development <br /> <br />73% <br />25% <br />2% <br /> <br />34% <br />31% <br />35% <br /> <br />1Modified from Bishop and Porcella [16]. <br /> <br />545 <br />