Could Drying Colorado River See Reservoirs Hit Dead Pool?
The Colorado River is one of the most important waterways in the Southwestern United States. But its levels are rapidly declining and are at the lowest they have been in a century.
The river starts in Colorado's Rocky Mountains and flows all the way down to the Gulf of California. The river also feeds into major reservoirs, such as Lake Mead, which is in Nevada and Arizona and was formed by the Hoover Dam, and Lake Powell, which is in Arizona and Utah and was formed by the Glen Canyon Dam.
These reservoirs are integral to the surrounding communities for providing water and power. If the reservoirs hit dead pool—meaning there is not enough water to flow past the dam—it could be a catastrophe. And if the Colorado River continues to dry up, so will the reservoirs.
Why Is the Colorado River Drying Up?
The declining Colorado River water levels are mainly due to the megadrought gripping the Southwestern United States. The drought has been ongoing for two decades and is one of the driest periods the U.S. has ever seen.
Douglas Kenney, director of the Western Water Policy Program at the University of Colorado Law School in the Getches-Wilkinson Center for Natural Resources, Energy and the Environment, told Newsweek: "Reservoirs are like bank accounts. They go up when deposits exceed withdrawals, and they drop when they don't.
"In the Colorado, we have problems on both sides of the ledger. Inflows [deposits] have been dropping for several decades now, primarily as a result of the warming climate," he said.
Over the past century, the Colorado River's flow has dropped by 20 percent, according to data from the U.S. Geological Survey.
In 2022, Lake Mead's water levels dropped to the lowest they have ever been, at 1,040 feet. They have risen only slightly since then, and they are projected to keep falling in the coming years.
Lake Mead could reach 992 feet by the end of July 2024, the U.S. Bureau of Reclamation reported in a two-year "probabilistic projection" for the Colorado River system. This is the "probable minimum" level the lake could reach within 24 months.
Lake Powell's water level has been falling for about 10 years. In March 2022, it fell below a critical level of 3,525 feet above sea level—the lake's target elevation.
Part of the problem is that as the megadrought is making weather patterns a lot less predictable, the river is not being replenished as quickly as it is being used.
"Demands [withdrawals] have steadily grown over the past century, as the Southwest has become a center of agricultural production and urban growth," Kenney said. "In recent years, we've made some real progress in reducing demands, but it hasn't been enough to keep pace with the drying out of the basin."
Why Is the Colorado River Important?
In total, around 40 million people rely on the Colorado River for water, including such major cities as Los Angeles and Denver.
"Many users have other options should Colorado River supplies be cut off, but for some, like farmers in California's Imperial Valley and residents of Las Vegas, the Colorado River is the only option. For those users, a loss of water deliveries would be catastrophic," Kenney said.
This is because agricultural operations would be hugely affected, as conditions would simply be too dry to grow anything.
"Without irrigation water, good luck growing lettuce in a 110-degree field that doesn't see rain for months at a time," Kenney said. "Likewise, if you enjoy fresh salads during the winter months in Chicago, you might need to rethink your menu.
"The economic impacts of a water-starved Southwest would easily run into the billions. The environmental impacts could be even more catastrophic. But, at the basin scale, this isn't an either/or scenario," he said.
A recent onslaught of heavy rains in the region has meant a slight increase in the Colorado River's water levels and, subsequently, its reservoirs. But this is not nearly enough to fix the ongoing problem. Because the region has been in a drought for so long, it would take years of rain to lift it out of a drought.
Since there does not appear to be an end in sight to the megadrought, many experts believe that a change in water policy is the only way to save the Colorado River and its reservoirs.
"Historically, water shortages have been solved by increasing demands through new dams, new diversions, new pumping projects—engineering solutions funded with federal subsidies," Kenney said. "At some point, those options, at least the ones that make some economic sense, have all been exhausted. That's where we are in the Colorado River Basin. Consequently, the most practical solutions today all involve reducing water demands."
He continued: "Over the past quarter-century, we've been really good at that. Virtually all major cities in the Southwest use the same or less water today than they did a couple decades ago, despite this being the fastest-growing population in the U.S. But urban use is just a fraction of agricultural use. Cutting water use in agriculture is much more difficult, especially on a tight time frame, as the only effective option is to take lands out of production."
Do you have a tip on a science story that Newsweek should be covering? Do you have a question about the Colorado River? Let us know via science@newsweek.com.
