Grand Canyon will be flooded in high-flow experiment for Colorado River

PAGE — Federal officials will flood the Grand Canyon Monday morning to help move sand and sediment down the Colorado River the way the river’s natural flows did before construction of Glen Canyon Dam.

The U.S. Bureau of Reclamation will open the bypass tubes on the dam for what scientists call high-flow experimental releases, aimed at rebuilding beaches and sandbars. The high flows will continue through Thursday.

Beaches and sandbars along the river have eroded since the construction of the dam in 1963, many totally disappearing into the clear waters of the Colorado River that ebb and flow with power demands. The dam has prevented sediment from flowing downstream.

Creating the artificial floods won’t result in the loss of water, officials said. The bureau will adjust scheduled flows from the dam to account for the high flows. Water from Glen Canyon Dam flows into Lake Mead, which supplies water to millions of people in Arizona, Nevada, California and Mexico.

The National Park Service is advising people who plan to be on the river or in the canyon this week to be aware of the higher flows on the river.

Monday marks the eighth time since 1996 that officials have conducted the controlled floods. The first flowed for more than seven days, peaking at 45,000 cubic feet per second.

This week the floods will last about four days, peaking at 38,100 cubic feet per second. The river’s flow from the dam typically varies between about 8,000 and 25,000 cubic feet per second, depending on hydropower demands.

A 16-day journey to the heart of the Colorado River

Tiny floods

Transporting sediment and sand down river used to be nature’s job. The Colorado River was muddy with sediment before Glen Canyon Dam turned the water clear. But those floods were larger and less predictable than this week’s experimental flows.

“These floods are tiny,” said Jack Schmidt, a geomorphologist at Utah State University and the former chief scientist at the Grand Canyon Research and Monitoring Center in Flagstaff. He was one of the researchers who devised the high-flow experiments.

The controlled floods are about half the magnitude of pre-dam floods, he said. They flow for several days, while the natural floods could continue for one to two months. And officials have triggered recent floods in November, he said, while snowmelt from the Rocky Mountains would raise water levels in May and June.

Other floods occurred in the fall, Schmidt said, “but not typically as late as November.”

The Paria River “occasionally and sporadically” delivers sand and sediment below the dam to Grand Canyon, he said.

So does the Little Colorado River, according to the Bureau of Reclamation.

But more than 90 percent of the sand and sediment that was once transported through Grand Canyon is now trapped in Lake Powell, Schmidt said. Water managers count on the artificial floods to move sediment downstream from the tributary rivers.

“These controlled floods are one way that we make the best out of a bad hand.” Schmidt said.

The sandbars and beaches that controlled floods rebuild can provide camping sites, create habitat for fish and wildlife, and protect plant communities and archeological sites, according to a federal environmental assessment.

No silver bullet

Some groups question whether the controlled floods are worth the cost, while others say they’re too little too late.

“I would prefer to see (controlled floods) designed to not be as impacting on hydropower,” said Leslie James, the director of the Colorado River Energy Distributors Association, whose members buy hydropower from Glen Canyon Dam.

During the controlled floods, some of the water generates power, but some of it bypasses the dam’s turbines, according to the Bureau of Reclamation. The Western Area Power Administration, a branch of the U.S. Department of Energy, must buy additional power later on to make up for the power that wasn’t generated by the diverted water.

The controlled flood this week, which flows from Monday to Thursday, will cost the agency an estimated $920,000, according to the Bureau of Reclamation.

While the accomplishments of the controlled floods are impressive, they don’t get to the heart of the problem, said Eric Balken, the director of the Glen Canyon Institute.

“In a way it is like putting a Band-Aid on a gaping wound,” he said. “It doesn’t actually get to the heart of the problem.”

He advocates for drilling new bypass tunnels around the dam to release the Colorado River through it, draining Lake Powell and restoring Glen and Grand canyons.

Glen Canyon Dam was an environmental mistake of historic proportions, he said.

The late Sen. Barry Goldwater, for example, came to regret his decision to vote for Glen Canyon Dam, his granddaughter, Alison Goldwater Ross, told the Arizona Republic.

But there is no “magic silver bullet” to solve all of Grand Canyon’s environmental problems, Schmidt said.

“At the end of the day Grand Canyon is a novel ecosystem,” he said. “We were never going to be able to restore the past.”

Environmental coverage on and in the Arizona Republic is supported by a grant from the Nina Mason Pulliam Charitable Trust. Follow the azcentral and Arizona Republic environmental reporting team at OurGrandAZ on Facebook, Twitter and Instagram.

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