But as the drought worsened, those same agencies increasingly appreciated that Mexico might be a land of opportunity. "They were running out of places to find water," says Gillon. "And Mexico was the one place that they haven't really squeezed every last drop out of yet."
In fact, since the early 1990s, the Metropolitan Water District of Southern California had contemplated the possibility of some kind of cross-border water swap. It could provide funding to help Mexican irrigation districts tighten their relatively inefficient water systems, thereby allowing them to grow the same crops using less water. In exchange, Metropolitan would increase its own water use upstream, in the U.S., by a corresponding amount.
During the summer of 2007, the Big Three agencies began quietly reaching out to their Mexican counterparts. Pete Silva, a scout for Metropolitan with long experience on both sides of the border, joined forces with Tom Carr from the Central Arizona Project and Bill Rinne from the Southern Nevada Water Authority, who died this August, to assemble what Silva dubbed, with some irony, a "strike team."
"There were a lot of hard feelings after the All-American Canal showdown," he says. But bad droughts can make for surprising alliances, and there was "just a feeling that somebody had to do something" to patch up relations with Mexico.
At the same time, a brainy, number-crunching analyst for the Environmental Defense Fund named Jennifer Pitt – a woman with a seemingly pathological drive to decipher the river's byzantine operational mechanics – began forging another set of informal partnerships across the border. Pitt, too, was focused on finding ways to free up water, but with a different goal: using it to restore the Colorado River Delta.
She also recognized that the Delta's champions needed to think more broadly. Six years after Minute 306 had been signed, conditions had only gotten worse. "Minute 306 demonstrated that it's very hard to get traction if you're just talking about the environment," she says. "It started becoming clear that we needed to look at what we were doing in the Delta in the context of bigger water-management decisions."
Pitt and other environmentalists taught themselves how to think like water bosses. She learned the computer program used to model drought scenarios, and began turning out a series of proposals that would help urban water managers weather the drought while also directing water toward the Delta.
But Pitt needed an ally to push the Delta's cause with the Mexican government. She found one in a Tijuana professor and researcher named Carlos de la Parra, who had served stints as a regional head of Mexico's Ministry of Environment and Natural Resources, and as the environmental attaché at the Mexican Embassy in Washington, D.C. Both jobs left him with close ties to leaders in the upper echelons of Mexico's federal environmental and water-management agencies.
"Carlos helped boost our ability not just to understand what (Mexican government officials) were thinking, but to seed some ideas to them as well," Pitt says. "I keenly felt the need (to have a counterpart) in Mexico, to know what's making them tick, and figure out how we could align the Delta with the rest of what they want."
In August 2007, then-U.S. Secretary of the Interior Dirk Kempthorne and Arturo Sarukhan, Mexico's ambassador to the U.S., announced that representatives of the two governments were beginning discussions about the river. The announcement marked the formal start of a five-year process that would culminate in a new amendment to the U.S.-Mexico water treaty, officially known as Minute 319.
As the talks progressed, de la Parra came to serve – one Mexican government official says with a laugh – as "plenipotentiary advisor" to that country's negotiating team. De la Parra and his counterparts within Mexico's water and environmental agencies helped push high-level government decision-makers past decades of indifference about what happened upstream in the U.S.
"For Mexico, the Colorado River had been the equivalent of a faucet stuck on the wall," says de la Parra. "That faucet had been delivering 1.5 million acre-feet a year" – the country's legal entitlement under the U.S.-Mexico treaty – "for almost 70 years. Why would Mexico want to look past that wall and see what was behind it?"
But as the drought ground on, he says, "Mexico realized that it needed to confront reality."
Mexico's water bosses understood that they were poorly prepared to weather the increasingly volatile climatic conditions that were also distressing their counterparts upstream. In the wide, flat Delta, there aren't many places to build a reservoir. But there was plenty of space free in lakes Powell and Mead for Mexico to "bank" water for the day that country might really need it.
A broader deal began to suggest itself. If Mexico agreed to share in shortages, argued negotiators such as Mario López, the head of international affairs for that nation's federal water agency, it should also be eligible for any future surplus water. "We said, 'We don't want the discussion to be focused only on the shortage situation,' " says López. "We need to see it as a whole."
The cornerstone of Mexico's negotiating package was water for the Colorado River Delta. Felipe Calderón, who had become president of Mexico in December 2006, brought a new, more pro-environment attitude to the federal government. Almost immediately, Calderón put José Luis Luege – a man with a solid track record as head of Mexico's environment and natural resources department – in charge of the country's federal water agency.
"The first priority for Mexico is to protect and to conserve the environment," says López. "It was state policy to push very hard on this" under Calderón.
Mexico's negotiators figured out that they could use citizen support for restoring the Delta to uphold their larger cause. "When Mexico starts talking in favor of environmental flows, it knows that it's got allies within the U.S.," says de la Parra. "In many ways, it is not negotiating country-to-country: It's negotiating on behalf of a value that is important on both sides of the border."
And the Delta's advocates had done their homework. During negotiations, they supported their argument for a Delta flood with modeling and probability analysis – the same tools water bosses used daily to understand the odds of going dry.
"Having solid science behind it helped a lot," says Hinojosa. He and his colleagues were able to show that the kind of water release they were proposing would require far less than 1 percent of the river's average annual flow.
"It didn't create major risks, in terms of shortage" to large water users like the Big Three, he says. "It was not a crazy, undoable proposal."
In early 2012, the negotiations were edging into their fifth year. Mexico initially proposed that Minute 319 run through 2026, but U.S. negotiators countered with a proposal to limit the agreement to just five years, through December 2017. Mexico agreed, but then turned to the environmental coalition for a specific, and robust, package of Delta flows. The team responded with a two-part proposal: A one-time, 105,392 acre-foot "pulse flow" to trigger tree germination and the creation of additional wetlands, backed up with a permanent 52,696 acre-foot annual "base flow" to maintain the new growth.
"We put up as much water as we thought we needed to be absolutely sure it is going to reach the mouth of the river," says de la Parra. "And the Mexican government said, 'We'll go for it.' "
Mexico committed to providing half of the pulse flow. But getting U.S. negotiators to provide the other half required devising a way to bridge a deep philosophical divide over whose water would actually be used for the effort. U.S. water bosses refused to send water to Mexico for use in the Delta, fearing it would wind up irrigating Mexican farms instead.
"We were crystal-clear from Day One," says Pat Mulroy. "If water was going to the Delta, it was going to be Mexican water – period."