High-flow experiment at the Grand Canyon aims to help Colorado River
Water is released from Glen Canyon Dam through bypass tubes, April 24, 2023, during a high-flow experiment. The flood will help move sand and sediment down the Colorado River the way the river’s natural flows did before construction of Glen Canyon Dam.
Mark Henle, The Republic
- Federal officials have confirmed that they will not flood the Grand Canyon this spring, citing ongoing work on Glen Canyon Dam and in the Colorado River downstream.
- Colorado River advocates say failing to flood the Canyon will hurt efforts to restore beaches and preserve the environment below Glen Canyon Dam.
- Some river advocates say the government’s decision may run afoul of the Grand Canyon Protection Act, which requires the feds to preserve ecological and recreational aspects of the Canyon.
Federal officials have rejected a plan to release floodwaters from Lake Powell to restore Grand Canyon beaches this spring, frustrating river advocates who question the government’s commitment to protecting the canyon’s environment.
Glen Canyon Dam has impounded the Colorado River near the Arizona-Utah line since 1963, and with it the annual load of sand that natural snowmelt floods previously churned up onto beaches and sandbars in the Grand Canyon each year. The U.S. Bureau of Reclamation, working through a collaborative adaptive management program to make the most of what sand a smaller tributary still deposits below the dam, has flooded the canyon by opening the dam’s bypass tubes 12 times since 1996.
With repeated decisions not to open the floodgates even when the sand is available, some are questioning whether the Glen Canyon Dam Adaptive Management Program is preserving Grand Canyon’s ecology and recreation as required under the Grand Canyon Protection Act of 1992.
“We are failing,” said Ben Reeder, a Utah-based river guide who represents the Grand Canyon River Guides on a technical work group that considers management options for the Reclamation Bureau.
“Deeply disappointed,” said Larry Stevens, a canyon ecologist who represents Wild Arizona and the Grand Canyon Wildlands Council on the work group.
Reeder and Stevens were among advocates and state agency officials who reluctantly agreed to forego a flood last fall in favor of saving the sand for a more naturally timed springtime flood. Events over the winter would interfere with that plan.
‘Looking for any excuse’ not to stage a flood
Reclamation officials said in April that they would recommend that new Interior Secretary Doug Burgum not authorize the flood because a National Park Service contractor was excavating in a slough downstream of the dam to disrupt its use as a spawning bed by non-native fish, including smallmouth bass. Work on relining the bypass tubes to protect their steel pipes also interfered.
On Thursday, May 22, the agency announced that the decision against flooding was final.
Those who had anticipated a rejuvenating flood said they appreciate the need to protect native fish from voracious predators like the bass, but that there’s too often some reason or another to reject bypassing the dam’s hydropower turbines to send water downstream, a cost to the dam’s power customers around the West. In 2021, for instance, the government declined to flood the canyon to prop up Lake Powell’s water level.
“It just seems like looking for any excuse not to do one,” Reeder said. The default appears to be against flooding in any given year, he said, perhaps because the team that ultimately recommends for or against does not include environmentalists or recreationalists.
“It really kind of bothers me, honestly, that we talk about the Grand Canyon in these economic terms as if it’s there for human consumption,” Reeder said.
Fresh off a May river trip, Reeder said beach erosion is apparent throughout the canyon. Rains from last year’s monsoon particularly battered one of his preferred camping beaches, at Stone Creek.
“We have a sand-starved system,” he said.
Environmentalists prefer a spring flood over fall, because it best mimics the river’s natural rhythm. Angler advocates also prefer spring, as it comes at a time that can better support a tailwater rainbow trout fishery, which has suffered in recent years as low water in Lake Powell led to a warming river. More than any flood, the trout need more water in the reservoir, pushing the warm surface farther from the dam intakes, said Jim Strogen, who represents Trout Unlimited in the adaptive management discussions.
“A deeper, colder lake is the best thing for that fishery,” he said.
Power providers say floods cost them money
The floods cost perhaps $1 million or $2 million in lost hydroelectric production, according to Leslie James, who represents mostly rural and tribal power consumers in the program as executive director of the Colorado River Energy Distributors Association. Last year, when there was no major flood but the dam managers regularly pulsed cold water through the bypass tubes to keep the river inhospitable to bass spawning, the agency said the cost in lost power production was $19 million.
The losses deplete a fund that pays for dam maintenance and environmental programs, James noted, and drawing more from that fund this year could cause delays in maintenance.
“We weren’t asked our views on (a spring flood), she said, “but if asked we would say that we always have concerns about bypassing hydropower generation.”
James said a repeat of last summer’s cool releases to combat bass seems unnecessary, as bass so far are generally restricted to the 15 miles below the dam and are not showing up dozens of miles downstream at the confluence with the Little Colorado River, a haven for native humpback chubs. Reclamation officials said they will decide in June whether to pulse cold water through the canyon this summer.
The agency reported that last year’s cool flows appeared to have worked, preventing any detectable growth in bass numbers by keeping the river mostly below 16 degrees Celsius — the temperature at which bass reproduce successfully — as far downstream as the Little Colorado. It also projected that without bypass flows this summer, temperatures in the river likely would rise above 16 degrees.
A federal biologist working on chub conservation told The Arizona Republic it would not be surprising if bass reach the Little Colorado by fall and reverse gains in the native fish population that allowed the government to downlist the chub from endangered to threatened in 2021.
The floods, achieved with blasts of water that jet across the canyon below the dam, can give the erroneous impression that water is lost downstream. In reality, while the floods do temporarily reduce Lake Powell’s elevation, they do not harm irrigators or municipal water providers. Lake Mead captures the water on the Grand Canyon’s west end and stores it for later use in Nevada, Arizona, California and Mexico.
Reclamation officials initially told participants in the adaptive management collaboration that a flood was unlikely in April, when Program Manager Bill Stewart said every attempt had been made to schedule it. When the groups and agencies had agreed to put off a flood last fall, he said, it had appeared there would be a window in May when both slough modifications and dam maintenance would be done. The plan was to flood the canyon for 60 hours, with a peak flow of 40,400 cubic feet per second, compared to routine flows in May ranging from 8,000 to 13,382 cfs.
During the transition in presidential administrations, work in the slough was delayed, leading to heavy equipment remaining in the river corridor throughout the month. Dam maintenance also lasted into the timeframe when a flood was envisioned, leaving some of the bypass tube capacity unavailable.
“We really did make every effort to make this happen,” Stewart told flood advocates tuning in to April’s virtual meeting.
Some participants, including Arizona Game and Fish Department biologist David Rogowski, said the program needs to improve its scheduling.
“We need to be better about planning for the future,” Rogowski said. “We aren’t doing (a spring flood) because of poor planning.”
Stevens agreed, saying Reclamation should incorporate planned floods into its routine maintenance schedule.
A river scientist who previously led the U.S. Geological Survey’s Grand Canyon research team said the Reclamation Bureau’s continuing trend of skipping opportunities to flood the canyon jeopardizes Grand Canyon National Park’s sandbars — a feature he said is as vital to the park’s natural environment as the sandstone walls looming above the river.
“It is disturbing that sand bars always come out second,” said Jack Schmidt, a Utah State University researcher and former head of the Grand Canyon Monitoring and Research Center. “It’s removing an entire landscape element.”
Brandon Loomis covers environmental and climate issues for The Arizona Republic and azcentral.com. Reach him at [email protected].
Environmental coverage on azcentral.com and in The Arizona Republic is supported by a grant from the Nina Mason Pulliam Charitable Trust.
Follow The Republic environmental reporting team at environment.azcentral.com and @azcenvironment on Facebook and Instagram.
