From National Parks Traveler:
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.
From the Deseret News (Alex Cabrero):
When construction of the Glen Canyon Dam began in 1956 to store water and generate electricity, it affected the natural flow of the Colorado River through the area and into the Grand Canyon.
This “experimental high-flow release” — the third of its kind in the past three years — is meant to kick up sand and sediment on the bottom of the river and move them downstream.
Scientists with the United States Geological Survey and other agencies say the force from the water will rebuild sandbars, beaches, recreation areas and animal habitat that would have been part of the normal environment if Glen Canyon Dam were never built.
“I wouldn’t judge whether that’s responsible or not, but that it is that you have changed something,” Tucker said. “Experiments like this are ways to find a meaningful way to restore or preserve that ecosystem downstream.”
Fifteen-thousand cubic feet of water per second is flowing out of the dam into the Colorado River.
To put that in perspective, a basketball is about one cubic foot. That means roughly 15,000 basketballs are being released out of the dam every single second.
“It’s something that is very visually striking to see,” Tucker said.
Releasing so much water doesn’t impact drought conditions, he said.
“The same amount of water is going to be released from Glen Canyon Dam throughout the year, so since this is a higher-flow period, obviously with the experiment that is here, that will be compensated for in other months where there will be less water that will go through the dam,” Tucker said.
This is the third in a five-year plan to conduct experimental high-flow releases.
More Colorado River Basin coverage here.