Top 14 Questions About the Colorado River—Answered!

The Colorado River starts in the Rocky Mountains of Colorado and travels about 1450 miles, providing water to seven U.S. States, 30 Tribal Nations and Mexico before ending in the Gulf of California.

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. While Tribal Nations have relied on the river for millennia, their water rights are included in each states’ allocation. The river 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.

Agriculture is the biggest user. Crops like alfalfa and cotton use a lot of water. Cities use less overall.

Thirty federally recognized Tribal Nations have legal claims to the river’s flow, but not all have access to or the infrastructure to use their share. Many are still fighting for water rights, access, and benefits from settled, quantified, and decreed water that remains undeveloped.

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 these reservoirs operate. The Upper Division States are focused on developing a framework that will help rebuild storage in Lake Powell and Lake Mead, and to bring water uses in line with available supplies.  Cities are conserving more. States and Tribal Nations are pushing for new agreements and solutions. 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 the river provides.

Yes. Even though the river was divided equitably between the Basins, 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 year-round agriculture and other uses rely on large, stable releases from Lake Mead—while Upper Basin uses are mostly rural, seasonal, and snowpack-dependent, with gradual increases in municipal demands. The Upper Division States strictly administer water based on available supplies, resulting in uncompensated, involuntary reductions to water supplies.

Because the geography and climate are different. The Upper Basin is mountainous with narrow valleys and high elevations, so the climate is colder.  Most of its water comes from snow that melts each spring. There are no locations to build large reservoirs like Lake Mead. The region mostly depends on snowpack and river flow as it happens.

Yes. Because the Upper Basin depends on snowmelt and natural flows, farmers and ranchers often receive less water during dry years because the State Engineer is actively administering water rights. This happens even when there is not a formal drought declaration. They’re already living with scarcity and making tough choices each season.