Creating a Sustainable Future


The key to maintaining the long-term viability of any activity or condition is the concept of sustainability. Protecting the Grand Canyon river experience and the future of guiding is no exception. To assure that our children and future generations will have the same opportunities and quality of experience is dependent on our ability to create a sustainable management program for the Colorado River. The quality of the experience of the future is fully dependent on maintaining the quality of the place that provides the experience. The way that the Colorado River is currently managed is clearly not sustainable.
Without a doubt the single greatest threat to the future of the Colorado River corridor in the Grand Canyon is the presence of Glen Canyon Dam. If we only look at river protection with a short-term view it is easy to make a case for maintaining the status quo regarding Glen Canyon Dam. The regulated flows from the dam create a degree of certainty upon which to plan and execute commercial river trips. In addition, there is a powerful urge in the human psyche to maintain a status quo that is perceived to be beneficial at the time. Change on the other hand takes effort and involves risk or even personal sacrifice. The status quo is always the path of least resistance but it is not necessarily the best or wisest path. The path of least resistance is to the left at Bedrock, but do you want to go there?
Supporting the continued operation of Glen Canyon Dam is a path that will eventually lead to disaster, just as sure as running left in Crystal at 50,000 cfs. It is becoming very clear that the construction of this dam was a huge mistake because it has created a situation that is not sustainable. The most obvious and unavoidable problem is the accumulation of sediment in the reservoir. It must be clearly understood that the primary natural function of the Colorado River is to transport the easily eroded soft sandstone of the Colorado Plateau to the sea. The forces of erosion and gravity cannot be denied. Within the scope of geologic time, this process is less than half completed. There is still enough sediment to be transported by the river to fill both Powell and Mead reservoirs thousands of times over. Sediment accumulation alone will eventually led to failure of the dam and subsequent unprecedented damage to the Grand Canyon and other resources downstream.
The huge sediment load carried by the Colorado River has been a known fact since the earliest river explorations. It is a tragedy that in 1954 Congress knowingly failed to adequately consider the seriousness of this problem. It is a little understood fact that one of the primary political reasons for building Glen Canyon Dam was to prolong the life of Hoover Dam and Lake Mead. In the years following the construction of Hoover Dam the rate of sediment accumulation in Lake Mead was alarming. It was clear that unless the huge annual sediment load of the Colorado River was trapped somewhere else upstream the life of Hoover Dam was limited. As is often the case, relatively short-term economic needs won the day and Congress authorized Glen Canyon Dam. Some future Congress would have to deal with the consequences.
In addition to serving as a sediment trap, the dam produced power generation revenue that the upper basin states used to construct more dams and diversions on the tributaries of the Colorado. This purpose has been fulfilled. Now society is faced with paying the price. Dealing with sediment accumulation in the reservoir, and paying for the huge losses of water that evaporate in periods of drought, will eventually cost far more than the initial economic benefits provided to the upper basin states. Time will prove that it would have been far less expensive just to have used tax dollars to pay for these upper basin storage projects and let the river run free through Glen and Grand Canyons.
In addition to escalating economic losses as a result of the dam, most boatmen are well aware of the severe ecological damage created both upstream and downstream of this dam. The National Park Service (nps) is responsible for protecting and managing the resources found within most of the Colorado River system north of Hoover Dam. The nps has a congressional mandate to protect park resources and natural processes “unimpaired for the enjoyment of future generations.” The body of law that creates this mandate is just as relevant to our culture as that which pertains to the management of water and power. The chronic impairment of the aquatic ecosystem of the Colorado River is well documented. In response to growing public concern over the adverse effects of the operation of Glen Canyon Dam on the resources of the Grand Canyon, Congress passed the 1992 Grand Canyon Protection Act. This act directed the Secretary of the Interior to mitigate the negative effects of the dam on downstream resources. An Environmental Impact Study (eis) was conducted and a Record of Decision (rod) was signed in 1996. The Glen Canyon Dam Adaptive Management Work Group (amwg) was established to advise the Secretary on dam operational changes authorized within the rod and to report on progress made in the mitigation progress.
An impressive amount of research and monitoring has been conducted in support of this effort. Beginning with the Glen Canyon Environmental Studies program which gathered information for the eis, and continuing with the Grand Canyon Monitoring and Research Center supporting the amwg, over a decade of research and associated experimental flows has been conducted costing taxpayers over eighty million dollars. Although much has been learned, very little progress, if any, has been made in actually reducing the impacts. The total demise of the natural biodiversity of the Colorado River ecosystem within the Grand Canyon is nearing completion. It is becoming increasingly clear that altering dam operations will not be effective in mitigating ecosystem changes brought about by the presence of the dam.
Although the current damages to Grand Canyon resources are tragic, future catastrophic events brought about by the accumulation of river sediment in the reservoir will be devastating.

Since the completion of Glen Canyon Dam in 1964, the Colorado’s nearly one hundred million ton average annual sediment load has been collecting in Lake Powell. It is an undisputed fact that unless a very costly annual dredging program is commenced soon, or the dam is decommissioned and a river bypass created, Lake Powell will fill with sediment.
However, well before the entire lake is filled with silt, the advancing sediment toe will first clog the dam’s river outlet works, the only openings that can be used to release water in times of low reservoir levels. Located at elevation 3374 (one hundred feet below the generator penstock openings), Bureau of Reclamation (bor) data estimates that sediment will clog these openings in about another eighty years (E. Shultz, 1961). In times of prolonged drought, if the reservoir level drops to elevation 3490 (within twenty feet of the center of the generator penstock openings), the generators must be shut down. If the existing drought continues, it is possible that this could occur within two years. In this event the outlet works will be used to bypass the generators in order to deliver the minimum flows required by law through the dam. No electric power would be generated until the lake level rose back above the penstock intake openings, which could be several years. This event, in itself, might not be more harmful to the canyon, but the scenario gets worse. Now fast-forward eighty years into the future. The outlet works are now clogged with sediment and the same drought scenario occurs. When the lake level drops below the penstock openings there is no longer any way to release water from the dam. Except for the inflows from the few small tributary streams within the Grand Canyon, the flow of the mighty Colorado will be a reduced to mere trickle.
As the sediment level continues to deepen it will reach the penstock openings in another fifty years. Unless there is a way to raise these openings higher on the face of the dam, there will no longer be any way to release water at any reservoir level. In wet cycles, because of drastically reduced reservoir storage capacity, the water level could easily reach the spillways. These spillways were not designed for the discharge of water for prolonged periods of time. High volume use of these spillways for more than a week or two would most likely lead to their catastrophic failure.
According to bor studies, over-topping of the dam would likely lead to the formation of a river channel through the soft sandstone on either side of the dam. Considering the tremendous water pressure created by a reservoir of this size and the easily eroded sandstone that abuts the dam, once the spillways failed, complete breaching of the dam could occur in a matter of hours. Such an event would be devastating to the inner gorge of the Grand Canyon. Following the near failure of the dam in 1983, the Bureau of Reclamation prepared a flood inundation model for the failure of Glen Canyon Dam (S. Latham, bor 1990). According to this study, in the event of overtopping or breaching of the dam the crest of the flood would be over five hundred feet high when it reached the Grand Canyon and 230 feet high when it reached Lake Mead. The study concludes: “ The failure of Glen Canyon Dam due to overtopping would produce catastrophic flooding with unprecedented flood depths and discharges all the way to Lake Mead and Hoover Dam. Even if Hoover Dam did not fail, there would be unprecedented flooding downstream of Lake Mead as well”.
Although the recent drought period precludes such an event occurring in the near term, the exposed sediment bed at the upper end of Lake Powell is a vivid reminder that the sedimentation process is well underway. The time to act is now before the situation becomes unmanageable. If dredging is to be the long-term solution, it must start immediately while the advancing sediment toe is still near the road access at Hite. If engineering studies prove that annual dredging will be too costly and impractical in this remote location, the nps and Congress should aggressively seek the decommissioning of Glen Canyon Dam. With a dam bypass the accumulated sediment can be carried naturally through the Grand Canyon over a period of years where it can be more easily dredged and removed at Lake Mead.
Although the legal and policy ramifications of this issue are complex and politically sensitive, there is compelling evidence that there would be both short and long-term positive economic benefits from restoring a free flowing river through Glen and Grand Canyon. The government could then focus its effort on managing Lake Mead as a sustainable water storage and hydropower facility. Resolving this critical problem will take courage and strong commitment to creating a sustainable future for the unique aquatic ecosystem of the Grand Canyon, Colorado Rivers water users, and Grand Canyon boatmen yet to be born.

Dave Haskell
Former Science Center Director for Grand Canyon National Park 1994–1999