Top 15 Questions About the Colorado River—Answered!

The Colorado River starts in the Rocky Mountains of Colorado and travels about 1,450 miles through five U.S. States and Mexico before ending in the Gulf of California. Or, at least it used to—today, it rarely reaches the sea.

It supplies water to 40 million people and 5 million acres of farmland. Major cities like Los Angeles, Las Vegas, Denver, Phoenix, Albuquerque, and Salt Lake City all rely on it. It also supports Tribal nations, ecosystems, recreation, and hydropower.

The river is divided by the 1922 Colorado River Compact, which apportioned it to the Upper Basin (CO, UT, WY, NM) and Lower Basin (CA, AZ, NV), and by later agreement with Mexico. Native American Tribes have relied on the river for millennia. It supports 40 million people across the American Southwest and Mexico.

Climate change, overuse, and a 20+ year megadrought have all contributed to shrinking flows. The river’s two largest reservoirs—Lake Powell and Lake Mead—have hit record lows in recent years. More water continues to leave those reservoirs than what now flows in.

It’s a nickname for the complex web of Compacts, treaties, laws, court decisions, and agreements that govern how the Colorado River is managed.

Most of the water is taken out for cities and agriculture. By the time the river reaches the Colorado River Delta in Mexico, there’s usually nothing left— though recent agreements between the U.S. and Mexico have restored some flow in select years.

Agriculture is the biggest user. Crops like alfalfa and cotton use a lot of water. Cities use much less overall, but their demand is growing.

Thirty Native American Tribes have legal claims to about 25% of the river’s flow, but not all have access to or infrastructure to use their share. Many are still fighting for water rights, access, and compensation for unused water.

Hotter temperatures mean more evaporation and less snowpack. Even in years with decent snowfall, runoff is often lower. Scientists call this a shift toward “aridification” rather than just drought.

They’re the two biggest reservoirs in the U.S., built to store Colorado River water. They’ve lost so much water in recent years that they’ve exposed old towns, boat wreckage—and even bodies.

Water managers are renegotiating how to reduce water uses. Cities are conserving more. States and Tribes are pushing for new deals. And there’s a growing push to include Indigenous voices and climate science in future planning.

People have proposed it—from the Mississippi, Columbia, and Great Lakes—but it’s wildly expensive, energy-intensive, politically controversial, and unlikely to solve the root problem: we can’t use more water than we have.

Yes. The Upper Basin (Colorado, Utah, Wyoming, and New Mexico) uses significantly less water than the Lower Basin (California, Arizona, and Nevada). The Lower Basin’s big cities and year-round agriculture rely on large, stable releases from Lake Mead—while Upper Basin uses are mostly rural, seasonal, and snowpack-dependent.

Because the geography and climate are different. The Upper Basin is mountainous and colder, and most of its water comes from snow that melts each spring. There are fewer locations to build large reservoirs like Lake Mead. The region depends on snowpack and river flow as it happens—what’s called a “hydrology-dependent” system.

Yes—automatically. Because the Upper Basin depends on snowmelt and natural flows, farmers and ranchers often receive less water during dry years, without needing a formal drought declaration. They’re already living with scarcity and making tough choices each season.