The Washington PostDemocracy Dies in Darkness

Changes needed to save second-largest U.S. reservoir, experts say

Wahweap Bay, located in Lake Powell along the Arizona and Utah border, has low water levels on June 9, 2021. (Ross D. Franklin/AP)
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Water levels in the nation’s second-largest reservoir dropped to a record low last week, raising the alarm that major changes are on the way for the seven states — and millions of Americans — relying on that system, experts say.

Lake Powell, a man-made reservoir that sits along the Colorado River on the Arizona-Utah border, generates electricity for about 4.5 million people. It is also a key part of the Colorado River Basin system, which supplies water to more than 40 million people. As of last week, its water levels fell to 3,522 feet above sea level, which is the lowest seen since the structure was filled in the 1960s. It’s now just 22 percent full, and unprecedented cuts in states’ water usage are necessary to avoid dire consequences.

“There’s too little supply and too much demand,” said Brad Udall, a water and climate scientist at Colorado State University. “Ultimately, I think what we’re going to see here is some major rewriting of Western water law.”

“We’re seeing a collision right now between 19th century water law, 20th century infrastructure and 21st century population and climate change,” Udall added. “And how this works out is anybody’s guess.”

A historic megadrought, the chronic overuse of water resources and the worsening climate crisis have sapped the Colorado River and endangered the Lake Powell reservoir and its Glen Canyon dam. If the reservoir drops to 3,490 feet, the dam may be unable to generate hydropower.

“We're 32 feet above where problems occur. And we've had years, recently, where we've lost 50 feet or more of reservoir volume,” Udall said. “We're one bad year away from reaching the point where we can't generate hydropower. That's the first worry here.”

At 3,370 feet, the reservoir becomes a “dead pool,” meaning water may be unable to flow downstream at all, cutting states off. “Lake Powell water is about a quarter of the water in the Los Angeles Basin. It supplies water to 90 percent of people in Las Vegas. It supplies water to about half of Phoenix. It supplies water that produces most of your winter vegetables,” Udall said.

The Bureau of Reclamation, which is in charge of the nation’s dams, recently propped up Lake Powell by flowing more water into the lake from upstream reservoirs, and reducing how much it releases downstream. However, those weren’t permanent fixes.

The Interior Department last year said that the seven states relying on the Colorado River — California, Arizona, Colorado, Nevada, New Mexico, Utah and Wyoming — need to reduce water usage by 2 to 4 million acre-feet. Six of the states reached an agreement on how to move forward. California, the biggest water user, was the lone holdout, and instead proposed a separate plan. Neither plan is enough.

“Now we’re trying to get everybody to get on one single, consensus plan,” which is a tremendous effort, said Ed Andrechak, water program manager at Conserve Southwest Utah. Andrechak noted the significance of the suggested cut, pointing out that 2 to 4 million acre-feet of water usage would be “somewhere around 25 or 30 percent of the total flow of the river.”

The snow and rain seen in the west this year isn’t enough to stabilize Lake Powell either, Andrechak said. “Now, the reality is, they’re all going to get a cut. Everybody should give,” he said.

And that must happen this year. The federal government is expected to mandate unilateral cuts this year if all seven states don’t come to an agreement.

“There’s no time left. The crisis is here. They don’t necessarily have to give it up forever. It might be temporary for several years until there’s improvements,” he said. But even if water levels do improve in the future, states cannot expect to return to former water usage entirely.

“Climate change is making sure that it’ll never get back to those levels,” Andrechak said.