Bureau of Reclamation response to the David Brower interview with the Lake Powell Chronicle.
Barry Wirth, Regional Public Affairs Officer
January 17, 1997
We have read with great interest the interview comments by David Brower, especially those concerning the physical well being of Glen Canyon Dam and the loss of water from Lake Powell.
thoughts concerning the safety of the dam. The single highest concern of the Bureau of Reclamation is the safety of our facilities. In the absence of any quantifiable data, it is unconscionable to suggest that there are
problems related to the safety of the dam that Reclamation has declined to discuss or hidden from the public. The safety records of Glen Canyon Dam, and all other 347 Reclamation dams, are a matter of public record.
The bottom line is, Glen Canyon Dam is safe and secure. The foundation is excellent.
The problem that Mr. Brower alluded to related to the damage the two spillways sustained in 1983 following the passage of flood
flows. Both spillways, which are tunnels around the dam through the sandstone cliffs, were extensively damaged. Significant cavitation was created by the vacuum effect of the water rushing through the tunnel. The
problems occurred because the earlier design of the spillways did not provide a means to dissipate the vacuum, not because of the geology of the site. The spillways were completely redesigned and reconstructed with
added air intakes to prevent cavitation prior to the 1984 seasonal runoff. Tests during that flood period verified that the redesigned spillways would perform to the highest safety standards.
Reclamation has never
hidden that event. In fact, it has been quite the opposite. We even produced an award winning video on the reconstruction of the spillways. Challenge at Glen Canyon
to this day remains one of our most popular videos distributed to the public.
As suggested by Mr. Brower, draining Lake Powell, "repairing" Glen Canyon Dam, and refilling the reservoir some 200 years from
now simply makes no sense since there is nothing wrong with the dam in the first place.
Concerning Mr. Brower's comments on water loses from Lake Powell, there is no question that there is water loss to evaporation
and bank storage. That is a fact with any large body of water. Here are the figures, as provided to the Sierra Club.
In Water Year 1996 (the water year runs from October 1 through September 30, similar to the federal
Fiscal Year), evaporation loses were 587,000 acre feet. Bank storage gain, which is water moving into the bank, was 368,000 acre feet. The total was 955,000 acre feet. However, when placed into the context of a
reservoir that ended Water Year 1996 with 26,215,000 acre feet in storage, the evaporative and bank storage loses were 3.6 percent. That is a very acceptable figure and a cost that is well worth the benefits provided by
One note concerning recreation and Mr. Brower's suggestion that Page, Arizona, be more like Moab, Utah. I submit that one reason both areas do so well is that each fulfills a unique role. While Moab has
wonderful slick rock bike trails, Page has the draw of Lake Powell. Within the region, they compliment each other, as do other attractions such as Grand Canyon and Zion National Parks. The fact that in 1996, over 2.5
million people visited the Glen Canyon National Recreation Area is testimony to the value the public places upon Lake Powell as a destination recreation site.
Mr. Brower also needs to better understand the role that
Lake Powell plays in water management in the seven-state Colorado River Basin. Because of the 1922 Colorado River Compact requirement that the Upper Basin States deliver a minimum of 75 million acre feet of water in any
10-year period to the Lower Basin States, storage at both Lake Powell and Lake Mead is critical. Without that storage, the Upper Basin States could never deliver the required amount of water in periods of severe
drought, such is in the late 1980's and early 1990's, and still use their full apportionments of the river. Even at current development levels in the Upper Basin States, it is unlikely that Lake Mead by itself could
meet the required demands of the Lower Basin States.
Glen Canyon Dam also plays a significant flood control role on the Colorado River. While many, including Mr. Brower, may speak to the benefits of a flood, I am not
sure that in this day and age too many people want to see floods of the historic level. Between the years of 1983 and 1986, over 50 million acre feet of water spilled from Glen Canyon Dam during those high water years.
Without the dam, it is safe to say at least another 26 million acre feet would have moved on down stream. Contrast that with the controlled and carefully managed flood last spring to rebuild beaches and rejuvenate
critical backwaters for endangered fish, and we see another commitment by Reclamation to manage with environmental sensitivity in mind.
Finally, some thoughts on the life of Lake Powell. Scientific sedimentation
studies conducted in the mid 1980's indicate that the overall life of Lake Powell is at least 700 years. In addition, it will be between 300 and 500 years before sediment reaches the power plant penstocks. The patterns
of sedimentation for the reservoir is that the upper reaches will fill in with the heavier sediment first, and over time the sediment will move downstream.
There is no doubt that within the next 300 to 500 years
tremendous new energy generation sources will be developed and/or invented. In the meantime, in Water Year 1996, Glen Canyon Dam Power plant generated 5.5 billion kilowatt hours, which was 75% of the 7.3 billion
kilowatt hours generated by the Colorado River Storage Project. That generation was from a power plant that is operating with the environmental constraints imposed by the recently completed Operation of Glen Canyon Dam
Environmental Impact Statement, a document developed with the participation of the Sierra Club and other environmental groups along with water and power users, recreational interests, and state and tribal governments.