Extreme measures under way to ensure Glen Canyon Dam can continue to generate electricity
The growing Colorado River crisis came under greater focus last week when the Bureau of Reclamation began emergency clearance from the Flaming Gorge Reservoir to prop up sinking levels in Lake Powell, now at all-time lows.
The move will raise Powell’s level by 3 feet in hopes of preventing it from falling to a point where Glen Canyon Dam would not be able to generate electricity, according to Wayne Pullan, the agency’s regional director for Upper Colorado.
These releases from Flaming Gorge and two other reservoirs were triggered by intergovernmental agreements made in response to historic drought conditions that are putting pressure on water supplies in the west.
“In contrast to an earthquake, a fire or a hurricane, it is not an imminent emergency, but a situation that has arisen for many years,” Pullan said on a media call on Friday. “Because of the way this has evolved over the years, we have been able to put this agreement into effect and be ready to act. There was no declaration of emergency. We see this as a reaction to a looming, very difficult situation. “
Thanks to poor drainage after a winter with little snow, the inflow into Lake Powell, Utah’s largest reservoir, is now about 30% of the average.
“The real concern was the dry soil and on top of that things just dried up,” said Pullan. “Sometimes there is a year when the snow cover is bad, but spring gets wet. But in the end we had a dry spring and a dry summer. “
Environmental group Save The Colorado argued that last week’s actions were too little late to have much of an impact, accusing the office of failing to consider how the changing climate has been reducing the river’s rivers for years.
“This is none other than climate denial that is robbing Peter of paying Paul,” said Gary Wockner, the group’s managing director. “The draining of reservoirs in the upper basin to support Lake Powell is likely a patch that is placed over an arterial hemorrhage. We don’t believe Lake Powell can be saved. “
When full, the lake covers about 165,000 acres; today it is only 74,000 acres. Life is now returning to its many side canyons and the Colorado River flows again through Cataract Canyon where its famous rapids are gradually returning.
Almost all of Utah is in either exceptional or extreme drought, likely in response to climate change that has increased drought in the west over the past two decades.
The main driver behind the decision to increase upstream releases was the Office’s latest 24-month study that Lake Powell levels were likely to drop to critical levels over the next year. Even with these total releases of 181,000 acre-feet, Pullan said levels could still drop below target.
Due to centuries-old water-sharing agreements between the seven states that rely on the Colorado as a source of water, the office cannot simply withhold water at Glen Canyon Dam. It is required to release predetermined amounts of water to satisfy Arizona, Nevada, and California stocks.
Pullan said these agreements served the Colorado River Basin states well, but they were based on assumptions that predicted much greater water availability than actually exists today.
“We are now in 2021 and the basic assumptions that we could rely on are starting to erode and we cannot rely on hydrology. And if we can’t rely on hydrology, we can’t count on hydropower and hydropower revenues, ”said Pullan. “We are really in a new era.”
The releases will lower the Flaming Gorge Reservoir on the Green River by 4 feet. In addition, New Mexico’s Navajo Lake will give up 2 feet on the San Juan River, while Colorado’s Blue Mesa Reservoir on the Gunnison River will lose 8 feet.
“The difference – even if the largest amounts come from Flaming Gorge – is due to the different sizes of these reservoirs,” said Pullan. “The larger the reservoir, the fewer differences in altitude there are with the given amount of water.”
The plan is to increase inflow into the Colorado River by 181,000 acre-feet by the end of the year, with most of that water coming from the Flaming Gorge, whose increased releases began last week and will run through September, along with releases from Blue mesa. The releases from the Navajo Lake reservoir run from October through December.
Pullan noted that these improved summer releases will improve the habitat for Colorado’s endangered fish species and increase electricity generation at a time of the year when it is most needed.
All three lakes are at the heart of major recreational areas, as is Lake Powell, where it has become almost impossible to launch boats in the Glen Canyon National Recreation Area.
The Flaming Gorge lies on the border between Utah and Wyoming and is about 83% full, according to the Utah Department of Natural Resources, which is well above the state average of 59%.
Today, Lake Powell’s water level is 3,556 feet above sea level and is barely a third full, according to the bureau’s database. That’s more than 15 meters lower than at this point last year and 31 meters above a critical 3,525-foot threshold designed to protect power generation at Glen Canyon Dam.
This sill provides a 35-foot buffer above the point where vortices created by the dam’s water turbines carry away air bubbles that would damage the generators, according to Christopher Cutler, who oversees the water and power supplies at BoR.
“The buffer is set up for two reasons. One is to give us enough time to respond to future hydrological changes. So if the flux continues to decrease, that gives us a little bit of buffer over the minimum current pool, which is 3,490 feet, ”Cutler said. “The other thing it gives us is a small buffer against the formation of eddies.”