Won't we lose an important water supply?
"Lake" Powell reservoir can store 27 million
acre feet of water. That's the equivalent of 27 million football
fields (minus the end goals) covered one foot deep in water, or
the annual flow of the entire river for two years. Similar to energy
supply, there is sufficient storage capacity within the Colorado
watershed to meet present and future demand - another 27 million
acre feet.
In fact, some water would be gained by draining the
reservoir, as an estimated 1.5 million acre feet per year is lost
annually due to evaporation from the reservoir and seepage into
the surrounding Navajo sandstone. Moreover, an enormous amount of
water is wasted through inefficient irrigation. For example, a seven
percent reduction of agricultural water use could double the available
supply of water for western consumers. Implementing more water-efficient
irrigation practices could free up as much as five million acre
feet a year, enough to satisfy projected growth needs for some 150
years, about the time the Glen Canyon Dam will have to be decommissioned
anyway because of sediment deposition.
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