Climate Change: The End of Glen Canyon Dam?

Colorado River flows have historically averaged 13.5 million acre-feet per year. Over the past five years, annual flows have declined to just 6.7 million acre-feet. Federal scientists warn that these lower flows may now be the norm as changing climatic conditions take root on the Colorado River basin.

In most years, nearly every drop of water is diverted from the Colorado River, yet plans are afoot to construct even more diversions. With demand now exceeding supply by 50 percent, a major crisis is looming.

Although ten percent of the country's population is connected to the Colorado River system, water managers continue to ignore this growing imbalance. Changes are urgently needed in how Colorado River water is managed, and it is critical that the environment is not short-changed in the process.

To avoid a major crisis, the federal government must immediately initiate negotiations with the seven Colorado River states to correct the basic flaw of allocating more water on paper than the river has to give. It must then establish efficiency standards and innovative solutions for all Colorado River water users. Lastly, it must conduct a basin-wide Environmental Impact Statement to determine the viability of maintaining the current inventory of dams in light of both declining flows and declining habitat.

If present climatic conditions persist as anticipated, Lake Powell is projected to run dry by 2007 and there may never be enough water to refill it.

Without Lake Powell, surplus water can be stored downstream in Lake Mead reservoir. In addition, eliminating Lake Powell will make more water available to downstream users by eliminating the tremendous water losses to surface evaporation and seepage from Lake Powell.

The region's energy grid has seamlessly accommodated the 35 percent reductions in Glen Canyon Dam's hydropower generation caused by the changing climatic conditions. Therefore, the public is unlikley to notice any change in energy deliveries from Glen Canyon Dam once output declines to zero.

As Lake Powell's water level decreases, sediment moves more quickly downstream toward the dam. This will accelerate the plugging of the dam's emergency bypass tubes, as well as the intake tubes for the dam's generators.

Additionally, even with changes in climate, bursts of high river-flow events could occur, via summer monsoon or a rapid snow melt, flushing decades of sediment build-up within the basin into Lake Powell in a matter of days or weeks.

The lowering of the reservoir is dramatically illustrating how sediment is the major hidden cost associated with Glen Canyon Dam. Climate change or not, there is no technical, feasible mechanism to move sediment through Glen Canyon Dam. Furthermore, the costs of dredging and transporting up to eight tandem-trailer truckloads a minute year-round from Glen Canyon would be astronomical. Grand Canyon needs this sediment, and it would be less costly to remove this sediment from Lake Mead reservoir downstream.

As nature's forces decrease the purported value of Glen Canyon Dam, the viability of a restored Grand Canyon ecosystem increases.