Having peaked on Thursday, high flows of the Colorado River through Grand Canyon National Park will taper back down to normal by Saturday, leaving behind replenished shores, improved fish habitat, and more space for campers. But the benefits will be lingering, according to the Glen Canyon Institute.
While the high-flow experiment, the third in six years, is being applauded by both the Institute and the National Parks Conservation Association, a news release put out by the Institute indicates the experiments are essentially useless in terms of the long-term health of the river as it flows through the national park.
'Once those sediments are redistributed from the channel to the banks, they are immediately attacked by a return to hydropower-driven, fluctuating flows,' said Dave Wegner, a former U.S. Bureau of Reclamation engineer quoted by the Institute. 'The result is that instead of protecting and stabilizing the new beaches, the return to normal hydropower-defined operating patterns from the dam act like putting a hot knife into a stick of butter ' the sand sloughs off quickly and right back into the river.'
The high-flow releases were to reach a peak volume of 37,500 cubic feet per second on Thursday, and taper back down to normal release rates of between 6,500 CFS and 9,000 CFS by Saturday afternoon. This is the third such experimental release since 2008. The United States Geological Survey estimates that the Colorado River below Glen Canyon Dam only has 6 percent of the sediment that it received before the Glen Canyon Dam was built in the 1960s. This sediment is vital to the health of the Grand Canyon ecosystem. While experimental high-releases provide some relief, the beaches ' and consequently the ecosystem ' of the Grand Canyon will continue to suffer until there is a systematic change in water management on the Colorado River that significantly increases the sediment flow in the canyon, according to the Institute.
In addition to the detrimental effect of normal releases from Glen Canyon Dam, as much as 95 percent of Colorado River sediment flows are trapped behind the Glen Canyon Dam, the Institute said. After 50 years of sediment trapping, the reality is that the beaches of the Grand Canyon are in a downward decline, it added.
'You can't cut off 95 percent of the sediment source and expect a sustainable supply for the beaches,' said Eric Balken, program director of Glen Canyon Institute. 'These high-flow releases give the public the impression that the Grand Canyon is doing OK. Make no mistake: the Grand Canyon is dying ' it is starved of life-giving sediment.'
At NPCA, officials said the high-flow experiment serves as an important measure to support endangered fish and help other natural and cultural resources in Grand Canyon National Park.
'This specially timed 'high flow' mimics pre-dam floods and will bring in sediment to build up sandbars along the river's bank,' said David Nimkin, Southwest regional director for NPCA. 'It will provide spawning habitat for fish and other wildlife species, better recreational opportunities for Grand Canyon boaters and other visitors, and keep sacred Native American cultural sites protected from the elements.'
The Department of Interior, which operates Glen Canyon Dam upstream from the Grand Canyon, is releasing the water as part of an experimental protocol resulting from a 2012 environmental assessment. An NPCA release said the goal of the protocol is to continue to fulfill the mandate of the 1992 Grand Canyon Protection Act, which stipulates that Glen Canyon Dam operations adapt with strong scientific research, to better protect the natural, cultural, and recreational qualities of the river within Grand Canyon National Park.
'Grand Canyon National Park is a beloved national treasure, visited by nearly 5 million visitors last year, generating $467 million in economic benefit,' said Mr. Nimkin. 'Managing the Colorado River to protect natural conditions in the Grand Canyon makes good ecological and good economic sense."
Since it was built in 1963, Glen Canyon Dam has regulated the amount of water that flows in the Colorado for its 277-mile stretch through the Grand Canyon. The dam was built to provide an inexpensive source of power for Southwest cities and industry, provide flood control, and store water for farms and communities in the region. Prior to the 71-story dam being erected, the river's seasonal peak floods averaged over 93,000 cubic feet per second. Since then, the flow of water through the dam's generating turbines has typically fluctuated between 8,000-25,000 cfs, according to power demand.
Several decades of such highly restricted water flow dramatically altered the conditions of the Colorado River and the canyon itself, prompting Congress to act to protect Grand Canyon National Park.
According to NPCA, Interior Department staff will incorporate data from these experiments, as well as other recent research, in an upcoming management plan that aims to balance the municipal, industrial, agricultural, cultural, recreational, and environmental interests at stake in the Colorado River and the Grand Canyon in years ahead. A draft plan is anticipated to be released for public comment in early 2015.
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