The Colorado River has long been regarded as the “lifeline of the Southwest.” It supplies water to 40 million people in seven states, 29 Native American tribes and parts of Mexico. Farmers use it to irrigate nearly 5.5 million acres of agricultural land.
One hundred years ago this month, the signing of the Colorado River Compact laid the foundation for how water from the river is used today. But the signers of the 1922 agreement had no way of knowing what the future would bring. Decades of overuse because of faulty science and population growth—along with climate change—have all reduced the river’s flow and the water levels in the nation’s largest reservoirs, Lake Mead and Lake Powell. Now, the basin is facing a crisis.
“The conditions that we’re experiencing now are far worse than anyone anticipated them to ever be,” Crystal Tulley-Cordova, principal hydrologist at the Navajo Nation Department of Water Resources, tells Smithsonian magazine.
So, how did the situation evolve into what it is today? And what comes next for the basin? Here are five things you should know about the 1922 agreement for its 100th anniversary.
Where is the Colorado River?
The 1,450-mile-long river begins in the Rocky Mountains of Colorado. It passes through Lake Powell, the Grand Canyon and Lake Mead before ending in Mexico’s Sonoran Desert. Altogether, its drainage basin spans about 246,000 square miles, representing 8 percent of the land in the continental United States.
While the river historically stretched all the way to the Gulf of California, damming and overuse have prevented the water from regularly flowing into the gulf since the 1960s.
What is the Colorado River Compact?
In the early 1920s, states in the Colorado River Basin grew concerned about their shares of water in the river. California was growing rapidly, and some feared it would establish priority access to the water.
Delph Carpenter, an attorney in Colorado, proposed that the states should come together to negotiate river water allocation. The states took 11 months to reach an agreement: the Colorado River Compact. It divided states in the watershed into an Upper Basin and a Lower Basin, which would each receive 7.5 million acre-feet of water per year. From there, the basins were left to figure out how to split up the water among themselves.
In the decades following the compact, subsequent court cases, treaties and agreements hammered out exactly how the water would be distributed. Together, these are called the “Law of the River.”
Who was involved, and who was not?
The compact was signed by delegates from seven states—Arizona, California, Colorado, Nevada, New Mexico, Utah and Wyoming—as well as a representative from the federal government, Secretary of Commerce Herbert Hoover. It was the first time so many states had come together to make an agreement—a momentous occasion in U.S. history.
But while Native Americans had been using water in the river for millennia and had legal rights to it, per a 1908 Supreme Court case, they were left out of the agreement, as was Mexico.
All states ratified the compact except for Arizona. Its then-governor said the compact put Arizona at a disadvantage, because it would be forced to compete directly with California for water. Arizona later joined the agreement in the early 1940s, and the two states still face bitter disputes over water today.
One century later, what has changed?
While the Law of the River still governs water use, conditions have shifted drastically in the 100 years since the compact was signed. Hoover predicted the basin’s population, which was about 457,000 in 1915, would quadruple. Today, the river serves 40 million people—more than 20 times his prediction.
And states are now using more water than is sustainable. The 1922 negotiations allocated water use based on data from an unusually wet period in history, Brad Udall, a senior water and climate research scientist at the Colorado Water Institute at Colorado State University, tells Smithsonian magazine. Now, with reduced water in the river and its reservoirs, these allocations are outdated. The signers likely knew their agreement would create a long-term problem, some experts say, but they ignored the research and forged ahead anyway.
“Uses are somewhere on the order of about 15 million acre-feet. The historical flow since 2000 is around 12 million acre-feet,” Udall says. “We’ve got a 3 million acre-foot imbalance.”
Meanwhile, climate change is reducing the mountain snowpack that feeds the river, and it’s also causing more evaporation. Warmer, drier conditions have thrown the entire basin into a 23-year-long drought that is ongoing. But Udall and other scientists argue the word “aridification” is a more accurate term, since the conditions are unlikely to change.
“Since 2000, the basin has been in a state of profound imbalance,” Udall says. “As a result, the Colorado River reservoirs, the nation’s two largest reservoirs, have declined by roughly 70 percent.”
The water shortage has forced the federal government to take drastic action—it has ordered cuts to water usage and reduced downstream releases from the Glen Canyon and Hoover dams, which form Lake Powell and Lake Mead, respectively. But even these measures haven’t been enough.
Native American tribes, which were excluded from the original 20th-century negotiations, have inherent rights to the diminishing water supply—a combined total of about 20 percent of the river’s historical flow. But many tribes are still fighting for these rights to be recognized.
“While people are conserving, we’re trying to develop our water,” Tulley-Cordova says. “A large population of our nation still don’t have running water.”
Jack Schmidt, director of the Center for Colorado River Studies at Utah State University, tells Smithsonian magazine the situation is dire. One more extremely dry winter—on par with the record-breaking dry conditions that occurred in 2002—will either drain Lake Powell or force the government to take unprecedented emergency action, he says.
“We’re in abject crisis right now,” Schmidt says. “We’re on the edge of that cliff. We’re about to fall off.”
What’s next for the basin?
The basin faces an immediate crisis of dry conditions this winter. But it also faces the long-term crisis of overuse, says Schmidt.
“We must, as a nation, reduce our long-term use rates to be consistent with the supply,” he says. “That's just basic checkbook accounting.”
In 2026, several current agreements regarding water usage will expire, forcing new compromises to be made about water allocation. So far, though, no one has decided what those new rules will look like.
“I don’t know where we’re going. I don’t know that anybody would tell you where we’re going. But if we don’t make decisions fast, nature’s going to make them for us,” Udall says. “The real threat here is that we empty these two reservoirs and then become reliant on an annual allocation that nature provides, instead of an annual allocation that we humans decide what’s best for us.”
But Udall says one reason to remain optimistic is that relationships between states and entities in the basin are good. And moving forward, Tulley-Cordova says that continuing to forge these relationships will be key.
“It’s not to say that we all agree on the way things should be done,” she says. “But the best [strategy for] talking about a complicated subject is not assuming what the other person’s priorities, needs, and challenges and opportunities are.”
Still, scientists say action must be taken—and soon. With Lake Mead and Lake Powell at historic lows and the states failing to cut back their water use, it’s only a matter of time before nature forces the states to make uncomfortable decisions.
“It’s going to be a wild ride. That much, I can tell you,” Udall says. “We’re in a deep hole here.”