Mapping Colorado River water: How California, Arizona and Nevada plan to use less

California, Arizona and Nevada, three of seven states that depend on the shrinking Colorado River for water and hydropower, plan to temporarily reduce the amount of river water they use by 13% over the next three years, federal officials have announced.

Will it be enough to alleviate the river's decline? It will help, but more measures will be needed, officials say.

River levels have fallen over the past 20 years with an extended drought and persistent overuse of river water. Climate change has hastened the reduction. And while this year's heavy snowpack is improving the river's flow, it won't be enough to overcome the effects of the drought.

How much water do states get

The three states have proposed to collectively cut their water use by at least 3 million acre-feet from now until the end of 2026. Details have not been disclosed.

The agreement, announced May 22, is now awaiting federal approval. It will help prevent water levels from falling further in Lake Mead and Lake Powell, the two reservoirs used by the states. Reservoir capacity has approached record lows in recent years.

One acre-foot is about 326,000 gallons, enough to cover 1 acre of land with a foot of water. An average California family uses one-half to 1 acre-foot of water a year for indoor and outdoor 

The pact was reached after the federal government threatened to impose restrictions of its own. It also highlighted the complex laws controlling water distribution from the river

The Colorado River Basin covers more than 246,000 square miles in seven states. It's governed by the Colorado River Compact, a century-old agreement allocating water to the states and Mexico.

States are in one of two sections:

• Lower Basin: California, Arizona and Nevada
• Upper Basin: Colorado, Utah, New Mexico and Wyoming

The water, measured in millions of acre-feet, is allocated annually:

• Lower Basin: 7.5 million
• Upper Basin: 7.5 million
• Mexico: 1.5 million

Cited as a breakthrough, the agreement came days before the May 30 deadline imposed by the Bureau of Reclamation for states to reduce water use. If the states hadn't agreed, federal authorities would have issued conservation proposals.

Under the three-state agreement, brokered by the Biden administration, the federal government will pay about $1.2 billion from the Inflation Reduction Act as compensation to those reducing water usage, including:

• Cities
• Native American tribes
• Farmers
• Irrigation districts

The pact now goes to the U.S. Bureau of Reclamation for approval. Representatives of all seven Colorado River Basin states, including the Upper Basin states of Colorado, New Mexico, Utah and Wyoming, will also review it.

The Colorado River, a vital source of water in the Southwest, winds 1,450 miles south from the Rocky Mountains in northern Colorado to the Gulf of California. It provides water to 40 million people in the seven basin states and two states in Mexico.

The river also is crucial for agriculture in basin states, irrigating about 5.5 million acres of land. About $60 billion a year is generated in crops and livestock.

Disputes over Colorado River water will continue. Several agreements governing water use will expire at the end of 2026.