Glen Canyon Dam
From Wikipedia, the free encyclopedia
Glen Canyon Dam is a dam on the Colorado River at Page, Arizona. The dam has been controversial since its inception, because it caused the flooding of Glen Canyon to create a man-made reservoir, Lake Powell.
The dam is 1,560 feet long along its crest, 300 feet thick at the base and 25 feet thick at the top. Its height above the Colorado River is 587 feet. Eight Francis type hydroelectric generators give it a generating capacity of 1,300 MW.
Its construction began in 1956. Although the dam was not dedicated until 1966, it was able to begin blocking the flow of the river in 1963.
The Sierra Club and other environmental organizations opposed the original plan for damming the Colorado River. When the plan was modified by the elimination of other proposed dams, however, the Sierra Club dropped its objection to the Glen Canyon Dam. Its then Executive Director, David R. Brower, later called this decision one of the biggest mistakes of his career:
- Glen Canyon died, and I was partly responsible for its needless death. Neither you nor I, nor anyone else, knew it well enough to insist that at all costs it should endure. When we began to find out it was too late.
(From The Place No One Knew, a Sierra Club book published in 1963)
Senator Barry Goldwater, who fought for funds to complete the dam, also later called its construction a mistake.
The dam has continued to attract opposition. In the novel The Monkey Wrench Gang, by Edward Abbey, the protagonists believe strongly that the dam has ruined the river. Since 1996, the Sierra Club has called for increasing the release of water, so that a more natural flow of the river is restored and Lake Powell is gradually drained.
High volume flows are now periodically released to assist in reearragement of river beaches in the canyon, necessary to prevent overgrowth of exotic plant species.
[edit] Controversy surrounds the dam
Owing to this dam, there has not been the periodic flooding that would wash away and renew sand banks along that portion of the Colorado River that transited the Grand Canyon. Because of the stability of the sand banks, several non-native species of plants became established, adversely affecting the native wildlife. However, it should also be noted that an endangered species, willow flycatcher, has been finding a new home in many of these non-native plant species. Some of these problems have been recently addressed by the experimental periodic releases of large amounts of water, which appeared at first to have had a beneficial effect upon the downstream ecosystem. The results of an experimental flood in early 2005 were mixed. On a positive note, new beaches were built for the rafting industry and the natural sandbars that species in the area depend on were partially restored. Negatively, however, excessive silt was flushed into Lake Mead reducing its capacity as a reservoir and recreation area, and at least half the population of an endangered fish species was lost during the flood, along with numerous trout and other gamefish.
[edit] External links
- Glen Canyon Dam National Recreation Area
- Glen Canyon Dam page from the Bureau of Reclamation
- Images of Glen Canyon before it was flooded
- Article by David Brower on restoring Glen Canyon
- The Glen Canyon Institute
- Maps and aerial photos
- Street map from Google Maps or Yahoo! Maps
- Topographic map from TopoZone
- Aerial image or topographic map from TerraServer-USA
- Satellite image from Google Maps or Microsoft Virtual Earth
