Environment

No End in Sight for Megadrought Crisis as States Fail to Agree on Use of Colorado River Water

In response, the Biden Administration has imposed new mandatory cuts — but they fall far short of what's needed.

ImaGeo iconImaGeoBy Tom YulsmanAug 16, 2022 9:45 PM
Hoover Dam
Hoover Dam holds back the waters of Lake Mead, the largest U.S. reservoir, as seen on June 28, 2022. At full capacity, the water reached almost to the top of the dam. Since then, it has dropped nearly 180 feet. To get a sense of scale, consider that this is more than 80 percent of the distance between the road bed of the Golden Gate Bridge and the water below. (Credit: © Tom Yulsman.

Newsletter

Sign up for our email newsletter for the latest science news
 

In June, the Biden Administration issued what seemed like an ultimatum to the seven states dependent on Colorado River water: agree on a voluntary plan for draconian cuts in their consumption, or the federal government would impose them unilaterally.

The demand, made by Bureau of Reclamation Commissioner M. Camille Calimlim Touton during Congressional testimony, came in response to unrelenting drought and overuse of water that's driving southwestern North America toward catastrophe. The deadline was Monday, Aug. 15.

And the states failed to meet it.

The bureau has now responded with an announcement of the deepest cuts yet to deliveries of Colorado River water from Lake Mead, the largest reservoir in the United States, and changes to the operation of Lake Powell, the second largest, located upstream. The goal is to protect them — at least for now — from dropping perilously low.

Lake Mead’s light-colored “bathtub ring” of mineral deposits towers nearly 180 feet above a speeding boat on June 29, 2022, near Hoover Dam. The deposits have been left behind as the lake has dropped to record low levels due to the worst megadrought in the region in 1,200 years, plus overuse of water. (Credit: © Tom Yulsman.)

“The system is approaching a tipping point, and without action we cannot protect the system,” Touton said during a news conference today.

Currently, Lake Powell is just 26 percent full, and Lake Mead is 27 percent full — both record lows. Combined storage of the major reservoirs in the upper and lower portions of the Colorado River Basin sits at just 34 percent of capacity, down from 40 percent last year, according to the latest numbers from the Bureau of Reclamation.

But even though the seven basin states — Colorado, Wyoming, New Mexico, Utah, Arizona, Nevada and California — missed Touton's deadline to agree on voluntary deep cuts, her agency did not respond as strongly as many water experts expected.

The bureau did declare what's known as a "Tier 2" shortage in the Lower Colorado River Basin. As a result, Arizona will see a 21 percent cut in the water it ultimately gets from Lake Mead during 2023. Nevada will get an 8 percent reduction, and Mexico will see a reduction of 7 percent. But California will see no cuts at all — at least not yet.

The reductions to be borne by Arizona and Nevada amount to 617,000 acre-feet of water. That is quite significant, and it follows on from major cuts made to Arizona's water deliveries during the current year. Even so, that number doesn't come close to what Commissioner Touton had asked for back in June: basin-wide cuts of 2 million to 4 million acre-feet of water.

To put those numbers in perspective, consider that in all of 2021, the Upper Basin states of Colorado, Wyoming, Utah and New Mexico used, in total — for cities, farms and industry — about 3.5 million acre-feet.

The turquoise waters of Lake Mead, with its “bathtub ring” of mineral deposits left behind as the reservoir has shriveled, stretch to the north in this panoramic image captured from the top Hoover Dam on June 29, 2022. The towers on the left and right are two of four that take in water to drive the dam’s hydropower turbines. The lake is at risk of dropping to what's known as "dead pool." At that point, not only would hydropower be impossible, but no water would flow downstream past Hoover Dam to users in Arizona and California — a true catastrophe. (Credit: ©Tom Yulsman)

In its announcement today, the Bureau of Reclamation touted recently passed legislation that it said will help the situation. This includes the recent Bipartisan Infrastructure Law, which provides $8.3 billion to address a number of issues nationwide, including water and drought challenges, plus $4 billion from the Inflation Reduction Act — signed into law today by President Biden.

But it was all "kind of anticlimactic" for Jennifer Gimbel, former deputy assistant secretary for water and science at the U.S. Department of Interior, and currently Senior Water Policy Scholar at Colorado State University's Water Center.

"It’s business as usual, but I guess we do have some money to spend," she says. "I worry that we’re spending too much on initial Band-Aids and not enough on a sustainable future."

John Entsminger, general manager of the Southern Nevada Water Authority, and the state's lead Colorado River negotiator, was much more blunt. Here are some of the things he said in a letter he sent to Interior Secretary Deb Haaland and other officials:

“Despite the obvious urgency of the situation, the last sixty-two days produced exactly nothing in terms of meaningful collective action to help forestall the looming crisis . . . We are at the stage where basin-wide every drop counts, and every single drop we are short [of the] two to four million acre-feet in permanent reductions draws us a step closer to the catastrophic collapse of the system . . ."

Megadrought

Way back in 1983, it probably would have been nearly impossible to imagine the challenge now faced by the 40 million people who depend on Colorado River Basin water. In that year, Lake Mead swelled so much with copious runoff that it exceeded Hoover Dam's capacity to hold it all back. As a result, torrents of water flowed into two gargantuan overflow spillways just upstream and on either side of the dam — each one designed to take in roughly the equivalent of the water flowing over Niagara Falls.

When Lake Mead last was at full capacity, as seen in this photograph taken in 1983, the water level reached almost to the top of the dam, and almost all of the iconic four towers, which serve as water intakes for hydropower turbines, were submerged. Water overflowed into two giant spillways, one of which is seen here in the foreground. (Credit: Donald Sandquist via Flickr Creative Commons)

In the late 1990s, Lake Mead came close to filling that much once again. But since the year 2000, southwestern North America, including the Colorado River Basin, has been gripped by a drought so severe that scientists have called it a "megadrought."

Recent research shows that it's the worst such drought in the region for at least 1,200 years. A little more than 40 percent of its severity was attributed in the study to human-caused climate change, largely from warming temperatures that have caused increasing aridity. This is why scientists call it a "hot drought."

Even in years with reasonably decent snowpack in the mountains of the upper basin — source of most of the river's water — runoff has been relatively paltry. That's because the anomalous heat has made plants and soils so thirsty that they've sucked up moisture before it could flow into streams and rivers.

One of Hoover Dam's two spillways, as seen on June 28, 2022. When water levels in the lake exceed maximum capacity, the spillways take the excess and channel it into tunnels 50 feet in diameter, and 600 feet long which are inclined at a steep angle, funneling the water around the dam. Each of the concrete-lined spillways themselves is about 650 feet long, 150 feet wide, and 170 feet deep and can handle roughly the flow of Niagara Falls. The last time they were used was in 1983 (see previous photo). Today, the spillways gather gravel instead of water. To get a sense of scale, consider that an entire U.S. Navy destroyer could easily fit in this concrete structure. (Credit: ©Tom Yulsman)

Looking to the Future

Warming is expected to intensify in coming years, so it would likely take mountain snowpack much above average for river flows to approach what they used to be. And that doesn't seem likely. So we should expect increasing aridity.

For now, the Bureau of Reclamation is acting simply to save Lakes Mead and Powell from dropping so low that water can no longer turn the turbines in the dams that produce hydropower. The bureau says it cannot let that happen because it would pose significant risks to the dams' infrastructure.

But at best, the bureau's action today will only delay the day of reckoning.

As Jennifer Gimbel puts it, "This just kicks the can down the road."

More From Discover
Recommendations From Our Store
Shop Now
Stay Curious
Join
Our List

Sign up for our weekly science updates.

 
Subscribe
To The Magazine

Save up to 70% off the cover price when you subscribe to Discover magazine.

Copyright © 2022 Kalmbach Media Co.