Arizona, California and Nevada might have reached a deal to conserve water from the drying Colorado River but it’s not enough to meet federal demands or the realities along the drying Colorado River, water experts say.

Those states, which make up the river’s lower basin, are reportedly close to an agreement that would cut the amount of water they draw from the waterway. They’re racing against the clock to find an agreement before the end of the month or else the U.S. Bureau of Reclamation might make the cuts for them.

But their proposed savings – reported Thursday by the Washington Post – amount to half of the minimum amount of water federal officials said the basin must save. And while the Colorado River’s headwaters saw an above-average snowpack this year, that extra water only buys the West a bit more time and the boon isn’t expected to last.

“The river is telling us that we haven’t done enough,” Jennifer Gimbel, a senior water policy scholar at Colorado State University said. “It’s challenging us.”

Water users in the lower basin, though, say they’ve already cut deep and they’re expressing optimism for the possible deal, looking upstream to potentially bridge the gap.

The proposal, which hasn’t formally been proposed, would mean the Imperial Irrigation District would be conserving nearly a quarter of its water supply, spokesman Robert Schettler said. Already those measures could mean that fewer crops come out of the major farming district in southern California (the largest water user in the most water-consumptive state), lowering national supply and raising prices. Digging deeper would exacerbate those issues, he said.

“That’s our only water source,” Schettler said. “We don’t have a Plan B.”

Officials with Reclamation said last summer that the seven states in the Colorado River Basin must find a way to save between 2 million and 4 million acre-feet. That’s up to a third of the river’s current annual flows, though climate change is exacerbating a decades-long drought and making it permanent so the amount of water in the river continues to decrease.

Negotiations to meet those federal requirements are fraught, pitting rural communities against urban ones and forcing a type of standoff between Arizona and California, the two largest water users on the river. Upper-basin states of Colorado, New Mexico, Utah and Wyoming offered a small effort, for their part, but water managers there are reluctant to commit further without more substantial movement from the downstream states.

Currently, the lower-basin states are nearing an agreement to conserve 3 million acre-feet over the next three years, The Washington Post reported. That’s half of Reclamation’s minimum required savings of 2 million acre-feet annually, though.

And the states would want to be paid more than $1 billion from the federal government to forego that water, the Post continued, citing state and federal officials familiar with the negotiations.

Massive amounts of federal money are available for conservation projects, Gimbel said. Programs are already in place to pay farmers and others to use less water and they’ve seen mixed results.

But paying people, businesses and states not to use water isn’t a long-term strategy, Gimbel noted.

She praised lower-basin states for coming together but noted that the water saved by the prospective deal wouldn’t be enough.

“It’s a combination of political will against the science that we’ve continued to ignore,” Gimbel said.

Gage Zobell, a water law expert and partner at the international law firm Dorsey & Whitney, said the proposal is effectively a low-ball offer. The lower-basin states appear hopeful that officials at Reclamation might be willing to meet them halfway, he said.

But those states can’t negotiate with the hydrological realities within the drying Colorado River, he said.

“Facts are facts,” Zobell said. “Unfortunately through the 120-year history of the river we’ve never gone on the facts, we’ve gone on political expediency and we’ve kicked the can down the road.”

Officials with Reclamation couldn’t immediately be reached for comment. Whether they’re inclined to accept the deal (assuming it’s formally proposed in the coming days) depends on a few things.

First, much depends on the upper-basin states, Gimbel said. If all seven states in the basin agree with the plan they could increase the political pressure for federal officials to accept the deal.

But all seven states have reached these kinds of deals before in the last 15 or 16 years, Gimbel noted. And the amount of water they’ve agreed to save still hasn’t been enough.

Officials for those upper-basin states couldn’t immediately be reached for comment.

Then, Schettler said upper-basin states could offer to conserve more water too and help meet Reclamation’s requirements.

“What are they going to contribute?” Schettler asked.

Upper-basin states put together their own five-point plan last summer and while it doesn’t offer much in the way of substantial water savings, those four states also use far less water. Arizona and California regularly exceed their allotted water use while upper-basin states have never yet used their full share of the river. The bulk of the savings, upstream water experts repeatedly argue, must come from Arizona and California.

Reclamation might have more leverage to reject the lower-basin’s deal, Zobell said. Secretary of the Interior Deb Haaland, who oversees the bureau, is legally the “water master” for lower-basin states, an authority granted to the position by Congress in 1928. So Haaland likely has the legal cover to force additional cuts.

But officials at Reclamation are still walking a fine line, Zobell said. Because if any of the states formally oppose the federal plan, the comment period for which closes at the end of the month, Reclamation must respond to their concerns. That would take time, possibly months, further delaying federal action, he said.

Or if any of the states sue the matter would end up before the U.S. Supreme Court, Zobell said. That would be an expensive proposition and cost even more time.

If a deal isn’t reached then Reclamation has two options to force cuts. The first would cut use from lower-basin states “based predominantly on the priority of water rights.” In short, those who have been drawing water from the river for the least amount of time would be the first to face cuts. That option would hit Arizona the hardest, particularly major cities like Phoenix and Tucson.

Or Reclamation could skip the priority system and more evenly distribute the cuts across the three states, which put California’s water supply more squarely in jeopardy.

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