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Show CEA Report Environmental Environmental Issues WATER LOSS f~** LEN CANYON DAM was built, in part, to ensure adequate V7 water supply to the lower basin states. However, evaporation and bank seepage result in a substantial loss of water to the system. An amount of water greater than the entire volume of the reservoir has been lost since 1963 due to evaporation and seepage. Without the reservoir, water would be made available to protect resources of Grand Canyon, for consumptive use, and for restoration of the Colorado River Delta ecosystem. • The total storage capacity of Powell reservoir was originally 27,000,000 acre- feet ( AF). • Powell reservoir loses 570,000 AF of water per year due to evaporation, compared to 102,000 AF along this section of the Colorado River prior to dam construction. 1 • This difference is enough water to supply Salt Lake City each year. This amount of water is worth $ 150 million at Salt Lake City water prices. It is estimated that if 10% of the 570,000 AF flowed across the border to Mexico, a substantial portion of the Colorado River Delta could be restored. 8 The cumulative loss due to evaporation since 1963 is 21,410,000 AF. 1 Water in the reservoir seeps into the surrounding porous sandstone. The total cumulative water loss due to bank seepage since construction of Glen Canyon Dam has been 10,000,000 AF. 1 The total cumulative loss due to evaporation and seepage, since the creation of Powell reservoir, is greater than 30,000,000 AF, or 2.25 years worth of river flow. 1 12 v ... . € 0 0 6 5 » 2> JS E mm o 4 2 0 12 108 204 300 396 60 156 252 343 Month from f/ 64 Figure 1 Cumulative seepage into surrounding sandstone as a result of the reservoir since January 1964. When reservoir level drops, some water is recovered, ( adapted from Myers, 1999). page 5 |