California, Arizona and Nevada reach major deal to use less Colorado River water

US president calls it 'important step forward' amid 'climate change and historic drought conditions'

The Colorado River has been in crisis for years due to a multi-decade drought in the West intensified by climate change, rising demand and overuse. AP

Arizona, California and Nevada on Monday reached a plan to significantly reduce their use of water from the drought-stricken Colorado River over the next three years, a breakthrough in a year-long stalemate that pitted western states against one another.

The plan would conserve an additional 3.7 million megalitres of water through 2026, when current guidelines for how the river is shared expire. A megalitre is 1 million litres. About half the cuts would come by the end of 2024.

“Today’s agreement between the Department of the Interior and seven Colorado River Basin states on a consensus-based approach marks an important step forward in our efforts to protect the stability of the Colorado River System in the face of climate change and historic drought conditions,” US President Joe Biden said of the deal.

The agreement amount is less than what federal officials said last year would be needed to stave off a crisis for the river amid a years-long drought, but still marks a notable step in drawn-out and difficult negotiations between the three states.

The 2,334-kilometre river provides water to tens of millions of people in seven states in the US West, parts of Mexico and more than two dozen Native American tribes.

It is responsible for producing hydropower and supplying water to farms that grow most of the nation's winter vegetables.

In exchange for temporarily using less water, cities, irrigation districts and tribes in the three states will receive federal funding, though officials did not say how much money they expected to receive.

“This approach will benefit the 40 million people who rely on the Colorado River Basin for agriculture, drinking water and power, and is a critical step to building a sustainable, resilient future for states, tribes and communities throughout the West,” Mr Biden added.

The three states – which form the Lower Basin – are entitled to 9.25 million megalitres of water altogether from the river.

California gets the most, based on a century-old water rights priority system. Under the new proposal, the state would give up about 1.9 million mega litres through 2026 – a little more than half of the total.

The Colorado River has been in crisis for years due to a multi-decade drought in the West intensified by climate change, rising demand and overuse.

Those pressures have sent water levels at key reservoirs along the river to unprecedented lows, though they have rebounded somewhat thanks to heavy precipitation and deep snowpack this winter.

The Associated Press contributed to this report