La Llorona Park in Las Cruces, New Mexico, burst to life in April. Joggers, children on bikes and chirping birds gravitated to a Río Grande that looked like a river again after more closely resembling a sand trail for months.

But local growers in the region’s agriculture-rich Mesilla Valley did not celebrate. Water released from upstream reservoirs flowed past their fields and onward to El Paso, Texas, with 12,000 acre-feet of it continuing to the Juárez Valley in the Mexican state of Chihuahua.

Some U.S. farmers and Texas officials complained that the release to Mexico, which took place over several days, was timed too early, possibly squandering the precious resource in a drought year. For their part, Mexican farmers, also buffeted by drought, argued the water couldn’t come soon enough. And U.S. officials, hearing from both sides, greenlighted the delivery, explaining they were only complying with a century-old treaty governing water-sharing between the two nations.

Tension in the run-up to the water release came amid deepening dissatisfaction with longstanding U.S.-Mexican water-apportionment accords—and calls that they be renegotiated. While experts don’t anticipate major treaty rewrites anytime soon, they cite a critical need for comprehensive, binational planning to boost efficient water use in the fast-growing border region, where water supplies are expected to tighten due not only to ongoing population growth, but also to climate change.

On the receiving end of border water complaints are officials such as Edward Drusina, commissioner for the U.S. section of the International Boundary and Water Commission (IBWC). Drusina says the IBWC—which monitors the 1906 Convention, the treaty governing water transfers to the Juárez Valley—must defer to the accord. While U.S. and Mexican stakeholders had differences in meetings on the timing of this year’s transfers, he says, Mexico ultimately is entitled to its share of water.

“I’m not saying [U.S. stakeholders] agreed with them 100%, but Mexico did not agree with delaying the deliveries,” says Drusina. He reports Mexico’s needs were exacerbated by mechanical problems affecting pumps used in the Juárez Valley to tap underground aquifers.

Drusina adds that the April transfer might be the only water delivery to Mexico this year. That amounts to far less than the 60,000 acre-feet annually that the U.S. owes Mexico under the 1906 Convention, which permits proportional reductions in drought years like this one.

The 1906 U.S.-Mexican treaty governs sharing of Río Grande water south of New Mexico’s Elephant Butte and Caballo dams to Fort Quitman, Texas, and the Juárez Valley of northern Mexico. A separate, 1944 agreement controls the sharing of Río Grande water in south Texas and adjacent Mexican jurisdictions.

History of friction

Stephen Mumme, a political science professor at Colorado State University, says the 1906 Convention has long been a source of U.S.-Mexican friction. With Mexico entitled to less than a tenth of the Río Grande’s flow, many Mexican stakeholders feel the U.S. holds all the cards in a treaty they view as “imposed” during the authoritarian reign of Porfirio Díaz, Mexico’s president from 1876 to 1911, he says. Tension eases when droughts do, Mumme says, but it “resurfaces at times of acute stress like this.”

For the second year in a row, drought is cutting heavily into the supplies of water governed by the 1906 treaty. This month the U.S. Department of Agriculture and National Weather Service noted spring run-off into Elephant Butte Reservoir is forecast to be 21% of normal. A 2011 U.S. Department of Interior report, meanwhile, warns flows in western river basins could shrink by 8% to 20% in the next 40 years.

Chihuahua lawmaker Alex Le Barón, president of his state legislature’s water-policy panel, says drought has created a “catastrophic situation” in his state. Other extreme weather has hammered Chihuahua, he reports, including freezes, fires and hail—the last of which lost him several hundred acres of chili peppers and oats this month. “If it’s not one thing, it is something else,” he says. “Climate change is impacting us in a dramatic way in our country.”

In response, farmers on both sides of the border are pumping more groundwater. Jesús Reyes, general manager of the El Paso County Water Improvement District No. 1, says irrigators are refurbishing existing wells or drilling new ones. Drawn from the border-straddling Hueco Bolsón aquifer, the water is not good for pecans and other key crops due to its salinity, Reyes says. He adds: “We’re in sad shape if we don’t bounce out of [drought] by next year.”

Such concern adds to pressure on both sides of the border for a reexamination of current and future use of the Río Grande. Drusina says U.S. and Mexican agencies this year hope to develop a water-delivery strategy for 2013 that avoids the tension of this year’s transfers.

Manuel Robles, a green activist and director of the Juárez Valley Regional Museum, cites the need for more efficient irrigation and other conservation gains. To raise awareness, he is reviving a campaign to have the river declared a United Nations Educational and Scientific Organization (Unesco) World Heritage Site.

Cross-border initiatives

A separate effort to promote binational water-policy dialogue is being spearheaded by Mike Barrera and the Río Grande Advisory Council (RAC), a non-governmental group in Laredo, Texas. RAC sponsors monthly phone meetings of government officials, environmentalists and others. Like Robles, Barrera says participants talk increasingly of a need to modify the 1906 Convention. The RAC, he says, will hold its first conference in Alamosa, Colorado, near the Río Grande’s headwaters, in August.

Chihuahua legislator Le Barón does not foresee a rush to renegotiate the 1906 Convention, but he asserts changes to the 1944 agreement governing the lower portion of the Rio Grande ought to be considered. Under that accord, he says, Colorado River water is sent from the United States to Mexican farmers in Baja California in exchange for shipments of water from Chihuahua to Texas, but is prejudicial to his state during climate emergencies.

Mexican water scholar Luzma Nava calls the 1906 Convention an “anachronism,” arguing a basin-wide balancing of water needs with river ecology is urgently needed. Says Nava, a researcher at Canada’s Laval University: “The tendency is to maintain things the way they are, the status quo, because reopening the [1906] Convention would require a lot of work.”