AFTER NEARLY A year of intense negotiations, California, Nevada and Arizona reached a historic agreement Monday to use less water from the overdrafted Colorado River over the next three years.

The states agreed to give up 3 million acre-feet of river water through 2026 — about 13 perecent of the amount they receive. In exchange, farmers and other water users will receive compensation from the federal government.

The Biden administration has been pushing the states since last spring to reach an agreement to cut back on Colorado River water deliveries. The three-state deal is a historic step — but it is not final: The U.S. Interior Department must review the proposal. And everything will have to be renegotiated before the end of 2026.

In California, the agreement would mostly affect the water supplies of farmers in the Imperial Valley. Coming up with a plan to fairly cut water use has created tensions between farms and cities and between states, especially California and Arizona.

Here’s what you need to know about the new plan, how it will affect California and whether it will bring relief to the West’s vital water supply system:

Why was this agreement needed?

The Colorado River basin has been overdrafted for decades. Its major reservoirs, Lake Mead and Lake Powell, have been steadily declining, threatening 40 million people in the West with a water supply crisis. 

In response, last June, a top Interior official asked the seven basin states to reduce water use by 2 to 4 million acre-feet per year, or a 15 percent to 30 percent annual reduction. The states failed to meet their deadlines to come up with a plan. So the Interior Department presented its own proposed actions last month, including a controversial one that would cut into the senior water rights of Imperial Valley farmers.

Unhappy with those federal proposals, California, Arizona and Nevada doubled down on their negotiations and tried to come up with an alternative. Monday’s agreement by the three states to cut water use through 2026 is considered a major, albeit temporary, step. At least half of the 3 million acre feet will be conserved by the end of 2024. 

The Interior Department has now retracted its plan so it can add the states’ new agreement to the package of options it is considering.

Bureau of Reclamation Commissioner Camille Calimlim Touton called the agreement “an important step forward towards our shared goal of forging a sustainable path for the basin that millions of people call home.”

Who is affected? Will they have to use less water? 

The agreement would affect the water supplies of about 19 million Southern Californians in six counties who receive imported water from the Metropolitan Water District.

But the impact will be minimal. The district will sacrifice 130,000 acre-feet per year that it usually receives through a transfer arrangement from farmers in the Palo Verde Irrigation District in Riverside and Imperial counties. That water, explained Metropolitan’s manager of Colorado River resources, Bill Hasencamp, will be left in Lake Mead instead. The federal government will reimburse the growers at the rate of $400 per acre foot.

Metropolitan will also voluntarily leave 250,000 acre-feet in Lake Mead this year. That water will be available for the district in the future.

These cuts will not affect Southern Californians this year, Hasencamp said. That’s because rains have greatly boosted supplies from the State Water Project. The state aqueduct delivered only about 100,000 acre-feet to Metropolitan last year, but will deliver 2 million this year. (An acre foot is roughly the amount that three households use per year.)

Still, Hasencamp said water conservation, both in communities and on farms, should remain a way of life.

“We need to be cognizant that the West is getting drier,” he said.

Farmers in the Imperial Valley are the biggest users of Colorado River water. The Imperial Irrigation District announced Monday that it will reduce usage at farms by roughly 250,000 acre-feet per year, about 10 percent of its average amount.

The district said it expects to receive $250 million from the federal government to reward the growers who cut back water deliveries. The money could be used to compensate growers who fallow crops.

Imperial Irrigation District General Manager Henry Martinez applauded the agreement, saying it is “is based on voluntary, achievable conservation volumes that will help protect critical Colorado River reservoir elevations, and in particular Lake Mead.”

With water from the Colorado River, arid Imperial County has become the ninth largest agricultural producer in the state, reporting $2.3 billion in sales in 2021, led by cattle and lettuce.

By acreage, alfalfa and other water-intensive crops used to feed dairy cows and cattle dominate in the Imperial Valley, covering more than half of its farmland. Imperial also produces two-thirds of the vegetables consumed in the U.S. during winter months.  

The Interior Department said it would use the Inflation Reduction Act to pay farmers and other users for saving 2.3 million acre-feet of water. The remaining 700,000 acre-feet “will be achieved through voluntary, uncompensated reductions by the Lower Basin states.” The Interior Department did not release how much it will spend or who would get the money.

What does the Colorado River need, long term? 

In most years, farms, cities and tribes use around 13 million acre-feet of the Colorado River’s water, which is significantly more than the 11 million acre-feet of rain and snow that feeds into the river system in an average year. Unless drastic cuts are made, these supplies — most importantly Mead and Powell, which together contain about 50 million acre-feet — could essentially run out of water within several years. 

While the new agreement amounts to saving about 1 million acre-feet per year, that’s not enough. Experts say at least twice that much must be conserved.

Since the lower basin states use most of the Colorado River’s water, the onus is on them — especially the biggest user, California — to come up with the water savings.

A wet winter has eased the emergency. But the relief will probably be short-lived in the arid West, where population growth and worsening droughts are sapping water supplies.

Sarah Porter, director of Arizona State University’s Kyl Center for Water Policy, said the agreement represents progress, even though more action is needed. 

“This is another step toward the long-term downward adjustment in how much Colorado River water we as a region can expect to take out of the system,” she said. 

Porter noted that this plan, because it’s a voluntary one, “gets us toward our 2026 goals without risk of litigation.”

Metropolitan Water District General Manager Adel Hagekhalil said Monday’s agreement offers some relief for Mead and Powell, but not a full solution. 

“Once the agreements are finalized, we must turn our attention to the much greater challenge ahead: developing long-term, post-2026 solutions to the imbalance on the river,” he said. 

This story originally appeared in CalMatters.