WASHINGTON>> The seven Western states that rely on water from the Colorado River may have run out of time for a compromise to share its dwindling supplies, just as new projections show reservoir levels could sink to a critical low by the end of this year.

The states missed a Saturday deadline set by the federal Bureau of Reclamation to agree on a plan to guide use of the river and the nation’s largest reservoirs, Lake Powell and Lake Mead, starting in the fall.

Existing rules, dating from 1922 and last updated in 2007, expired last year and no longer reflect the reality of a river basin that has been warming and drying steadily in recent decades.

“The federal deadline for a consensus agreement on managing the Colorado River after 2026 is passing for a second time without resolution,” the governors of California, Arizona and Nevada — whose states make up the river’s Lower Basin — said. “Our stance remains firm and fair: All seven basin states must share in the responsibility of conservation.”

But in two years of negotiations, the Upper Basin states — Colorado, New Mexico, Utah and Wyoming — have resisted any permanent cuts in water use because their water supply, upstream of the massive yet shrinking reservoirs, is more highly variable. And during the driest years, they are forced to take steep usage cuts. Lake Powell, straddling Utah and Arizona, divides the Upper and Lower basins.

Now, amid one of the driest winters in decades across the mountains that feed the Colorado River and its tributaries, the need for cuts in water usage are more dire than ever. Reclamation Bureau officials said they expect flows into Lake Powell during the water year that ends in September to be 52% of average, potentially rendering Glen Canyon Dam unable to produce hydroelectric power as soon as December.

“The basin’s poor hydrologic outlook highlights the necessity for collaboration,” Scott Cameron, the acting Reclamation Bureau commissioner, said in a statement.

Without a seven-state deal on water use cuts, it would be up to federal officials to divvy up a source of water that sustains 40 million people and irrigates millions of acres of crops. And any plan the Trump administration imposed would most likely spark litigation and end up in the U.S. Supreme Court.

Reclamation Bureau officials did not respond to requests for comment about the negotiations.

Arizona, California and Nevada have offered to decrease Colorado River allocation by 27%, 10% and 17%, respectively, according to those states.

U.S. Sen. John Hickenlooper, a Colorado Democrat who helped negotiate a river contingency plan in 2019 as governor, called the situation in the Colorado Basin “dire,” pointing to the state’s low snowpack.

“If we don’t address this problem together — head-on and fast — our communities, farms and economies will suffer. The best path forward is the one we take together. Litigation won’t solve the problem of this long-term aridification,” Hickenlooper said.

Leaders across the river basin have been sharpening their rhetoric around the likelihood of a legal battle in recent weeks, saying they are preparing lawyers to defend their water supplies. Nevada’s chief water negotiator joined them Friday.

“The river doesn’t care about legal interpretations, political comfort zones or arguments about why a state can’t do more to conserve,” John Entsminger, general manager of the Southern Nevada Water Authority, said in a statement. “While I will continue to work with my Colorado River counterparts in hopes of finding a workable solution to this crisis, we must also prepare to fight for our water supply if it comes to that.”

In a joint statement, Upper Basin leaders said they would continue to negotiate while also hinting at a belief that they hold the upper hand in court battles to come. They said they had “proposed serious, implementable solutions grounded in today’s hydrology” even as the dry conditions mean water users across the Upper Basin would use less than 60% of the water they are entitled to this year.

After the states missed a deadline in November, Reclamation officials set the Saturday deadline to allow time for any water-use plan to pass through federal reviews and be finalized by Oct 1.

The Trump administration in January released several alternatives to manage water sharing and is accepting public comments until March 2.

The scenarios underscore how the lower-basin states — and Arizona in particular — stand to lose the most water if river management is left up to the federal government. That is because the Reclamation Bureau operates the dams impounding lakes Powell and Mead but has little control over water supplies upstream of the reservoirs.

The Associated Press contributed to this report.