Living Rivers - Colorado Riverkeeper
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Save Grand Canyon Again
Grand Canyon Campaign
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Grand Canyon & Glen Canyon Dam: The Basics
The Restoration Journey
Colorado River Water Storage Without Glen Canyon Dam
Climate Change: The End of Glen Canyon Dam?
Other Reasons to Decommission Glen Canyon Dam
Species in Peril

Colorado River Water Storage Without Glen Canyon Dam

Misunderstanding surrounding Glen Canyon Dam's water storage capability and Colorado River water waste are the major factors delaying Grand Canyon's restoration. Although the reservoir behind Glen Canyon Dam, Lake Powell, is part of the present Colorado River plumbing system that distributes water into seven states and Mexico, its absence will not cause faucets to run dry.

Each year, Lake Powell loses up to one million acre-feet of water due to evaporation into the dry desert air, and seepage into the reservoir's porous sandstone bank-two times Las Vegas' annual water consumption. Every drop remaining in the Colorado River currently gets used. The river no longer reaches the ocean, thus recovering this wasted water would be incredibly valuable to people and ecosystems alike.

Increasingly, water managers in the Colorado River basin are turning to storing water in underground aquifers, minimizing evaporative losses. Implemented on a wider scale, such approaches offer storage opportunities not explored when Glen Canyon Dam was built.

Diminishing Returns

The Colorado River basin is the most developed river system in the world, with more than 40 major dams and reservoirs. However, the water storage value of reservoirs follows a law of diminishing returns: the more storage reservoirs constructed in a basin, the more water lost daily due to evaporation. Even before Glen Canyon Dam was completed, it was recognized that the benefits of its storage capacity would be largely offset by evaporative losses. Twenty percent of the Colorado River's annual flow is now lost to evaporation and seepage from its reservoir system.

After evaporation and seepage, nearly all the water left in Lake Powell flows downstream to the reservoir behind Hoover Dam, Lake Mead. Thus, Lake Powell is not needed to service major water users. Government models reveal that in average years water users below Glen Canyon and Hoover dams would experience no decrease in water availability without Glen Canyon Dam, largely because Lake Powell's significant evaporation and seepage losses would be eliminated.


With or without Glen Canyon Dam, the Colorado River water system is in collapse. More water is allocated on paper than the river has historically delivered. The problem is not a lack of water, but a lack of responsible water use.

Forty percent of Colorado River water is wasted on alfalfa and other forms of cattle feed requiring up to four times the amount of water necessary to grow food directly for human consumption. Meanwhile, residential consumers in the region pour half their water onto non-native landscaping unsuitable for the region's temperate and desert ecosystems.

Eliminating such waste would pave the way for restoration well beyond Grand Canyon, allowing the decommissioning of other unnecessary dams in the Colorado River watershed.

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Last Update: August 6, 2004

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Living Rivers    PO Box 466     Moab, UT 84532     435.259.1063