Stirring things up on the Colorado River
Whether the flood will live up to its billing as a grand realignment of America's way of dealing with the downstream effects of dams is another matter. Scientists, politicians and interest groups will be debating that for months after the scientific data are in.
Still, on March 26 and throughout the next week, the Bureau of Reclamation committed what agency veterans might consider blasphemy: It opened the valves and spilled stored water from Lake Powell, bypassing the turbines which make Glen Canyon Dam a virtual cash register. It created the very kind of flood dams are built to prevent.
The purpose was two-fold: to restore the Grand Canyon's disappearing beaches, and to scour out backwater areas critical to wildlife habitat, especially that of the all but extinct humpback chub.
"I was up here when this dam was built in the "50s, and at the time it didn't occur to anybody the relation between the dam and what would happen downstream," Babbitt recalled during a pre-flood float trip with reporters through what remains of Glen Canyon downstream from the dam. "Now what we're doing is understanding everything relates, and if we're going to find equilibrium on this landscape we're going to have to see the entire watershed as a unit and manage it as an ecosystem."
The ecosystem has been out of whack for 30 years now. The dam environmentalists love to hate traps 90 percent of the Colorado River's sediment flow in Lake Powell. The river, which used to run warm and muddy, now runs clear and cold. And gully-washing spring floods have been replaced by controlled flows timed only to meet power needs in Sunbelt meccas such as Phoenix, Las Vegas and Los Angeles.
"What's happened is the dam converted one of our pristine national treasures into a flush toilet," says Larry Lake, whose Western River Expeditions is the largest boat-trip operator through the Grand Canyon.
Over the past 10 years, river guides have been shocked by the rapid erosion and disappearance of beaches. Downstream flows have eroded what beaches existed, and with only clear water running downstream, they haven't been able to rebuild. The idea of the intentional flood was to stir sand lying in the Colorado River channel, suspend it in the rising water, and let it settle out as the water was slowly drawn back down.
Some river guides were skeptical, but most applauded any effort to rebuild beaches. "Within four or five years it's conceivable we're going to have a very difficult time providing river trips," Lake says.
With all four jet tubes open, the great flood of "96 measured 45,000 cubic feet per second. That's a huge increase from normal power operations which usually top out at 12,000 cfs, but it's still sparse compared to the pre-dam gully-washers which could hit 200,000-300,000 cfs for weeks at a time.
"It's a trickle compared to what Mother Nature could provide," Reclamation scientist Dave Wegner says. "But to the Grand Canyon, it's essential that we find a better way to operate the dam."
More than 150 scientists floated downstream ahead of the flood to set up monitoring equipment, including a real-time connection to the Internet to provide a play-by-play for scientists worldwide. Many of the principles learned from this flood experiment could apply elsewhere. Babbitt wonders, for instance, if Pacific Northwest salmon streams could benefit from intentional floods.
There may be other, unintended, side effects. Fishing guides and scientists are concerned the trout fishery which has blossomed just below the dam (due to the clear, cold water which has extirpated most native fish) may be wiped out.
"High flows may push the trout out of the fishing area," said Wegner, adding that the insects the trout eat could be disrupted as well. And one Park Service official who did not want to be quoted by name admitted the first few miles below the dam won't see the benefits of flooding, but instead will become a "sacrifice area."
But, the river runners who love to berate Glen Canyon Dam were lined up along the shore at Lee's Ferry, waiting for the flood flow to hit. It's not often these days when true high water comes roaring down the Colorado.
For more information contact: Dave Wegner, Glen Canyon Environmental Studies, P.O. Box 22459, Flagstaff, AZ 86002 (520/556-7363).
- Larry Warren
Larry Warren is reports on the environment for KUTV News in Salt Lake City, Utah.