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