Western states grapple with a shrinking Colorado River

Last week, the Trump administration unveiled a new 10-year plan for managing the shrinking Colorado River, which supplies water to 35-40 million people across the American West.

After years of negotiations, falling reservoirs, and increasingly tense debates between states, federal officials are hoping their new proposal can keep the river from running dry long enough to find a permanent solution.

How did we get here?

In 1922, seven US states—AZ, CA, CO, NV, NM, UT, and WY—signed an agreement on how much water each state could use from the waterway, called the Colorado River Compact.

However, that deal was made during an unusually wet stretch when the river was carrying far more water than it does today.

• Since 2000, the Colorado River has shrunk dramatically, while Lake Mead and Lake Powell—the two largest lakes on the river—have fallen to their lowest combined levels on record.
• Scientists estimate roughly half of the Colorado River's declining flow has been driven by rising temperatures, with additional warming expected to further reduce water levels.

That’s where a new federal proposal comes in

Under the Trump admin’s plan, the Lower Basin states—California, Arizona, and Nevada—which have historically used the most Colorado River water would shoulder most of the burden of mandatory water cuts.

• Between 2027-28, California would reduce usage by ~12%, Arizona by ~31%, and Nevada by ~28%, with water allocations reevaluated every two years depending on conditions.
• If the drought worsens, the Lower Basin could ultimately see cuts of up to 40% of their combined allotments.
• Meanwhile, the Upper Basin states, Colorado, New Mexico, Utah, and Wyoming, would continue pursuing voluntary conservation measures rather than mandatory reductions.

But…The latest plan doesn’t permanently settle the debate among states. The Lower Basin states say all Colorado River users should share the burden of cuts, while the Upper Basin states argue they’ve never used their full legal share of water in the first place, so mandatory cuts shouldn't fall on them.

Looking ahead: Experts say the dispute over Colorado River rights will likely spark a future legal battle between affected states, which is expected to eventually reach the Supreme Court.