Why Is the Colorado River Drying Up?

The Colorado River's water levels are the lowest they have been in a century.

Scientists fear the reservoirs the river feeds into could reach deadpool level in the next few years. That would mean the water level would be too low to flow downstream from a dam or to drive turbines to generate power. And these reservoirs are integral for surrounding water supply.

The river is one of the most important across the Southwestern United States and northern Mexico. It provides water for around 40 million people in the surrounding areas, and supplies water to 5 million acres of farmland.

Over the last century, the river's flow has dropped by 20 percent, according to data from the U.S. Geological Survey.

Two of the river's reservoirs are now less than a third full. One of these is the largest man-made reservoir in the U.S., Lake Mead, which stretches across Nevada and Arizona. As of December 17, Lake Mead's water levels stood at 1,043 feet, or only around 27 percent of its usual capacity.

Lake Mead could reach 992 feet by the end of July 2024, according to a two-year "probabilistic projection" of the Colorado River system by the Bureau of Reclamation. This is the U.S. water-resource management office's "probable minimum" level the lake could reach within 24 months.

The river is not the only one in the U.S. to be reaching dangerously low levels. The Mississippi River's water levels are also the lowest they have been in a decade.

Why Is the Colorado River Drying up?

The Colorado River stretches across the Southwestern United States—an area gripped by the most severe megadrought since around the year 800. And the future is difficult to predict.

Jennifer Pitt, Colorado River program director with the National Audubon Society, an environmental organization, told Newsweek: "The Colorado River has experienced an extended drought for the past 23 years, exacerbated by climate change. Rising temperatures are drying out the region, resulting in less flow in the river. Climate change means it is not possible to predict the river's future. There is no historic precedent for today's conditions."

This stretch of drought has been as bad, and even drier, than any other recorded in the U.S. in the past 1,200 years. It is largely being put down to human-driven climate change.

Amid the drought, people are using up the river's resources far more than they used to do. This, paired with the dry conditions, means that the water is not replenishing as fast as people are using it.

Rainfall amid the megadrought is not the only factor at play with the Colorado River's declining water levels.

Water levels usually fluctuate seasonally due to winter snowpack flowing down from the Rocky Mountains.

But due to climate change, seasonal weather patterns are becoming harder to predict. The lack of precipitation in the area has caused the Colorado River, and its reservoirs, to stay at a consistently low level.

"The decline of flows has been so great that we need to adapt. The seven Colorado River Basin states, Tribes, irrigation districts, municipal and industrial water users, and the federal government must agree to water reductions necessary to stabilize the river and reservoir system," Pitt said.

There is particular concern circling around Lake Mead. The lake is formed by the Hoover Dam and generates electricity for hundreds of thousands of people.

If the lake's water continues to dry up, there is a possibility that the dam's turbines will no longer be able to generate power. This would happen if the lake reached a reservoir elevation of 895 feet, a level where water would not flow past the dam.

This would mean that the water levels were too low to flow through the Hoover Dam, ceasing that electricity supply.

"Fortunately, the federal government has provided significant resources through the Bipartisan Infrastructure Law and the Inflation Reduction Act to improve irrigation infrastructure, support urban reuse and habitat restoration, and fund water conservation," Pitt said. "We will continue to advocate for multi-year water conservation agreements and durable projects that are part of long-term solutions to reduce water use and improve the health of our rivers and watersheds."

How Many States Does it Run Through?

The Colorado River stretches for 1,450 miles through Nevada, Arizona, California, and into Mexico. It provides water to seven 'basin states' which include Arizona, California, Colorado, Nevada, New Mexico, Utah, and Wyoming.

"The Colorado may be the world's hardest working river. It supplies water for tens of millions of people in the U.S. and Mexico, dozens of Native American tribes, and millions of acres of irrigated agricultural lands," Pitt said. "The river and its tributaries are essential in supporting more than 70 percent of all wildlife in the region—including birds like the California Condor, Southwestern Willow Flycatcher, Yellow-breasted Chat, Sandhill Crane, and Summer Tanager."

What Is the Source of the Colorado River?

The Colorado River begins at a small lake on the Poudre Pass in Rocky Mountain National Park, in the mountains of northern Colorado.

From there, it flows to the Grand Lake in Grand County, Colorado, then down to Lake Granby—the third largest body of water in the state. When it arrives in Granby, the water begins to split and is diverted to neighboring states and reservoirs.

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