Artificial Flood Failed to Solve Grand
Canyon Problems, Scientists Say
Source: The Salt Lake Tribune
The idea was to churn sand and silt from the bottom of the river channel and distribute them on the banks, sandbars and side canyons where they could help the fish, flora and fauna in one of the world's premier natural wonders.
After letting the high water flow for two weeks in the spring of 1996, Babbitt declared the $1.5 million, 110-billion-gallon experiment a success.
Today, scientists say the benefits of the artificial flood were short-lived, if not illusory. The inner Grand Canyon's ecosystem may even be in worse shape.
"We're sort of back to where we were before the '96 flood. Some measures tell us we have less sand than before," said Jack Schmidt, a Utah State University geography professor and leading Colorado River expert.
Research during the past three years has shown the assumption upon which the 1996 flood was based -- that sediment accumulates from year to year deep in the river channel -- was wrong.
The much-ballyhooed new beaches created by the flood were not from sediment stored in the channel but mostly from a redistribution of sediment in eddies and on the banks. Rather than settling in the channel, sediments are being flushed downstream by the flows released from Glen Canyon Dam to satisfy hydropower and water needs in Arizona, Nevada and California.
Schmidt and four colleagues from the U.S. Geological Survey and Northern Arizona University in Flagstaff will soon publish their findings in Eos, a journal of the American Geophysical Union.
Complicating matters in the Grand Canyon is the continuing decline of the humpback chub, an endangered native fish whose survival is dependent, in part, on backwaters and eddies created by a constant influx of sand and silt.
The latest surveys show there are just 2,000 humpback chubs in the Grand Canyon, down from 8,300 in 1993.
"If something is not done significantly in the next two years to improve the habitat, that fish is gone," said Nikolai Ramsey, a scientist for the Grand Canyon Trust, an environmental group based in Flagstaff.
The downward trends in sediment and the humpback chub population have prompted geologists and fishery biologists to call on river managers to take bold steps to try to reverse the situation.
Later this month, the Glen Canyon Dam Adaptive Management Working Group -- a federally appointed board composed of Colorado River water users and environmentalists -- will meet in Phoenix to discuss possible changes in dam operations.
Schmidt and his colleagues have recommended another large release of water from Glen Canyon Dam, which forms Lake Powell and traps 90 percent of the sediments that once regularly nourished the Grand Canyon.
This time, though, they suggest the release occur soon after the monsoons of late summer and early fall, to take advantage of sediments deposited in the Colorado River channel from tributaries below the dam, such as the Paria and Little Colorado rivers. According to the Eos article, those sediments stay in the river channel for just one to three months.
"We need to get that stuff out of the channel and onto the banks," Schmidt said. "If you wait and screw around, it will just go down to Lake Mead," the reservoir behind Hoover Dam in southern Nevada.
The best alternative, said Schmidt, is a 200-mile pipeline that would transport sediment from the upper reaches of Lake Powell to the Colorado River below the dam.
That alternative, however, would be costly and take several years to realize, making the fall flooding proposal simpler -- at least in theory.
Legally, a fall flood may not be possible, said Wayne Cook, director of the Upper Colorado River Basin Commission.
Cook said federal laws appear to prohibit the Department of Interior from releasing water from Lake Powell beyond the dam's power plant capacity of 31,000 cubic feet per second (cfs) unless that water is a threat to the dam. The artificial flood in 1996, justified by an extremely wet winter, involved a release of 45,000 cfs, which required 14,000 cfs to bypass the power plant through tubes in the dam.
Because Lake Powell is well below its capacity in the fall, an artificial flood for the Grand Canyon that time of year is unlikely, Cook said.
Pamela Hyde, director of Southwest Rivers, a Flagstaff environmental organization that is part of the working group, disagreed.
"I don't think those [laws] need to be interpreted that strictly," she said.
Since 1996, however, water and power interests have consistently resisted calls for additional artificial floods. T hose interests are pushing for additional testing rather than another flood, Hyde said.
With scientific evidence building that the Grand Canyon's health is deteriorating, environmental groups, which for the past decade have worked cooperatively with water and power interests, are beginning to lose patience.
For the first time in a decade, they are hinting at legal action under the Endangered Species Act and the 1992 Grand Canyon Protection Act.
"If we can't get [the water and power interests'] cooperation to improve the habitat and health of the river," said Grand Canyon Trust Director Geoff Barnard, "the alternative is to revert to a pitched battle . . . which could be a true disruption of their lives."
Publication date: 2002-04-10
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