Interior Dept. Favors More Canyon Flooding
October 29, 2003
By Mitch Tobin, ARIZONA DAILY STAR
Despite initial resistance, the Bush administration favors continued experimental floods meant to restore the Grand Canyon's ecology, a senior official said in Tucson on Tuesday.
Assistant secretary of the Interior Bennett Raley, the administration's point man on water issues, spoke to 60 scientists at the start of a three-day meeting on how Glen Canyon Dam affects the Colorado River.
Researchers explained how they're using lasers, underwater cameras, century-old photos and experimental flumes in Minneapolis to learn how sand grains and Volkswagen-sized boulders move through the Canyon's rapids and eddies.
Raley urged the scientists not to politicize their work and to remember that "science is not the only input factor for management of the Colorado River."
"If scientists are sloppy and mix advocacy with science, you will end up with the same public perception of integrity that lawyers have," said Raley, a lawyer by training.
Glen Canyon Dam, completed in 1963, dramatically altered the Colorado's flow. Before the dam, the warm, muddy river roared with spring snowmelt. Sediment was lifted onto beaches and sand bars, creating wildlife habitat and backwaters vital to native fish, such as the endangered humpback chub. The beaches are still important campsites for boaters.
After the river was plugged to stabilize the Southwest's water supply, it ran colder and clearer below the dam, which trapped 90 percent of the silt. But dam releases - which often fluctuate with the Sunbelt's electricity demands - have also caused the Colorado's baseline flow to double downstream. As a result, much of the silt and gravel deposited by the Grand Canyon's 740 tributaries gets whisked into Lake Mead downstream.
"It wasn't that we just lost the spring floods, which redeposited sand," U.S. Geological Survey researcher Ted Melis said, "we lost the low-flows the rest of the time, which were low enough to retain those inputs for use during the high-flows. We're getting hit on both ends."
The result is an ecosystem transformed by a dam that helps supply water and power to 25 million people. Tucson is becoming increasingly dependent on the Colorado, whose water comes here via the Central Arizona Project's 336-mile canal.
After passage of the 1992 Grand Canyon Protection Act, the Clinton administration tried to replicate the river's natural flows. With much fanfare, Interior Secretary Bruce Babbitt opened the dam's floodgates in 1996; another flooding experiment was tried in 2000. Despite initial claims of success, scientists now say the results were minimal. A lack of sediment in the river made it tough for sandy areas to expand, and many gains were quickly washed away.
Scientists want to create more floods and time them when the Paria River is dumping sediment into the Colorado. But the drought has caused that tributary, 15 miles below the dam, to deposit less silt in the past three years than any time in recorded history.
Raley said at first he was "deeply, deeply skeptical about the experimental flow program." But, after talks with scientists on a river trip, Raley accepted it was "good science and it was worth taking the political risks to move forward."
"We know when we're being gamed. Had we sensed that, we probably would have slow-walked, ducked, evaded and done everything not to move forward," he said.
John Weisheit, an environmentalist with the group Living Rivers who would like to see Glen Canyon Dam removed, was encouraged by Raley's words. But he said the Interior Department still isn't spending enough money to restore the Grand Canyon.
In the past 30 years, researchers have flip-flopped on whether the Canyon was losing or gaining sediment, said Jack Schmidt of Utah State University. Some thought the lack of floods created a surplus of silt and there was enough sand in the river to form new beaches.
"What we've learned in the Grand Canyon is, the system may be in sediment deficit all the way to Lake Mead," he said. Contact Mitch Tobin at 573-4185 or mtobin@azstarnet.com