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
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
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.