Extreme actions underway to ensure Glen Canyon Dam can continue to generate power

Flaming Gorge will drop by 4 feet to keep water levels at Lake Powell above critical threshold for power generation.

(Rick Egan | The Salt Lake Tribune) Trees are exposed again in Iceberg Canyon, on Tuesday, May 18, 2021.

The growing crisis on the Colorado River came into sharper focus last week when the Bureau of Reclamation began emergency releases from Flaming Gorge Reservoir to shore up Lake Powell’s declining levels, now at historic lows.

The move will bolster Powell’s level by 3 feet in hopes of preventing it from dropping to a point where Glen Canyon Dam would not be able to generate electrical power, according to the agency’s Upper Colorado regional director Wayne Pullan.

These releases from Flaming Gorge and two other reservoirs were triggered by interstate agreements crafted in response to historic drought conditions that are stressing water supplies across the West.

“Unlike an earthquake or a fire or a hurricane, it’s not an imminent emergency, but it’s been an emerging situation over many years,” Pullan said Friday in a news media call. “Because of the way this has emerged over the years, we’ve been able to have this agreement in place and to be ready to act. There’s been no declaration of emergency. We consider this a response to an emerging, very difficult situation.”

Thanks to poor runoff following a low-snow winter, inflows into Lake Powell, Utah’s largest reservoir, are now about 30% of average.

“The real concern was the dry soils and then on top of that, things just dried up,” Pullan said. “Sometimes you’ll get a year where the snow pack is bad, but the spring will turn out to be wet. But we ended up with the dry spring and a dry summer.”

The environmental group Save The Colorado argued last week’s action is too little too late to have much of an impact, and accused the bureau of failing to account for how the changing climate has been diminishing the river’s flows for years.

“This is nothing more than climate denial that robs Peter to pay Paul,” said Gary Wockner, the group’s executive director. “Draining upper basin reservoirs to try and prop up Lake Powell is likely a Band-aid placed over an arterial hemorrhage. We do not believe Lake Powell can be saved.

When full, the lake covers about 165,000 acres; today it covers only 74,000 acres. Life is now returning to its many side canyons and the Colorado River again flows through Cataract Canyon, where its famed rapids are gradually returning.

Nearly all of Utah is in either exceptional or extreme drought, likely in response to climate change that has increased aridity in the West over the past two decades.

Prompting the decision to increase upstream releases was the bureau’s latest 24-month study that Lake Powell’s level would likely drop to a critical level next year. Even with these releases, totaling 181,000 acre-feet, the level could still fall below the target elevation, according to Pullan.

Because of century-old water-sharing agreements between the seven states that rely on the Colorado as a water source, the bureau cannot simply hold water back at Glen Canyon Dam. It is obligated to release predetermined amounts of water to satisfy Arizona, Nevada and California’s shares.

Pullan said these agreements have served the Colorado River Basin states well, but they were based on flow assumptions that predicted a lot more water availability than actually exists today.

“Here we are now in 2021, and the basic underlying assumptions that we’ve been able to rely on are beginning to erode and we can’t count on the hydrology. And when we can’t count on the hydrology we can’t count on the hydropower and hydropower revenues,” Pullan said. “We’re really in a new era.”

(Paul Fraughton |The Salt Lake Tribune) Flaming Gorge Reservoir in 2011.

The releases will lower Flaming Gorge Reservoir, on the Green River, by 4 feet. Additionally, New Mexico’s Navajo Lake on the San Juan River will give up 2 feet, while Colorado’s Blue Mesa Reservoir on the Gunnison River will forfeit 8 feet.

“The difference in this—even though the largest volumes come from Flaming Gorge—is due to the fact that there’s a disparity in the size of these reservoirs,” Pullan said. “The bigger the reservoir, the less the the elevation drops will occur for the given amount of water.”

The plan is to augment flows into the Colorado River by 181,000 acre-feet between now and the end of the year, with most of that water coming from Flaming Gorge, whose increased releases started last week and will run through September, along with releases from Blue Mesa. Releases from the Navajo Lake reservoir will run October through December.

Pullan noted that these enhanced summer releases will improve habitat for the Colorado’s endangered species of fish and increase power generation at a time of year when it’s need most.

All three lakes are centerpieces of major recreation areas, as is Lake Powell where it has become all but impossible to launch boats at Glen Canyon National Recreation Area.

Straddling the Utah-Wyoming state line, Flaming Gorge is about 83% full, well above Utah’s state average of 59%, according to the Utah Department of Natural Resources.

Today, Lake Powell’s water level sits at 3,556 feet above sea level and is barely one third full, according to the bureau’s database. That’s more than 50 feet lower than it was at this point last year and 31 feet above a critical threshold of 3,525 feet, set to protect power generation at Glen Canyon Dam.

That threshold provides a 35-vertical-foot buffer above the point at which vortices created by the dam’s hydroturbines begin to entrain air bubbles that would damage the generators, according to Christopher Cutler, who oversees water and power services at the BoR.

“The buffer is put in place for two reasons. One is to give us enough time to react to any future hydrologic changes. So if the river continues to decline, it gives us a little bit of buffer above the minimum power pool, which is 3,490 feet,” Cutler said. “The other thing it gives us is a little bit of buffer against the creation of vortices.”