Alonso Montañez killed the outboard, and the boat swung against the scum and trash that had accumulated in the stagnant water on the high side of the dam.
“Escucha,” he said, gesturing at the surface of the lake.
In the quiet, we heard water slapping the hull, a life jacket buckle pinging on a metal pole. “Listen,” he said again. “You can hear the force of it, no?”
The sound was imperceptible at first. But soon enough it emerged, swelling upward from the murky emerald depths beneath our little boat. The sound was like an enormous rainstick held underwater.
Montañez, muscle-bound in a tight blue t-shirt, explained we were hearing the sediment-infused water of La Boquilla Reservoir sluicing into the dam’s gigantic outlets. “That’s not something you want to hear,” he said.
Our boat drifted closer to the dam’s wall, a mighty concrete curtain pressed between two desert peaks. Montañez pointed out six gates, each about 12 feet wide, the tops poking out just above the water’s surface. These were the reservoir’s outlets. Under normal conditions, Montañez told me, they would be far below the lake’s surface. “You should never be able to see these,” he said. “This dam was not designed for the water to get this low.”
Montañez is a tour boat operator and fisherman on La Boquilla Reservoir, the largest reservoir in the northern Mexican state of Chihuahua and a body of water whose drastically dwindling supply portends ever-more hardship for the drought-stricken Rio Grande. Never in the history of Mexican National Water Commission records has La Boquilla plunged to its present levels. The day we motored up to the dam—September 21, 2024—the reservoir had sunk to 16.1 percent of its capacity. This May, the reservoir sat at 14.7 percent.
La Boquilla impounds the water of the Rio Conchos, the largest tributary of the Rio Grande. With a capacity of more than 2.35 million acre-feet—enough, in other words, to submerge 2.35 million acres of land in a foot of water—La Boquilla can be thought of as a gigantic storage tank perched at a high point in a complex binational river system.
If the lake lacks water, the river below it dries. And a dried-up Rio Conchos signals distress and political tensions extending throughout northern Chihuahua and all along Mexico’s border with Texas.
Historically, the Rio Conchos served as Mexico’s most reliable workhorse for delivering water to Texas in accordance with a treaty negotiated by the United States and Mexico in 1944. But it’s become increasingly apparent that decades of megadrought and overexploitation have ridden the old river nearly to death.
The desiccation of the Rio Conchos is partly to blame for unprecedented water shortages experienced by Rio Grande Valley farmers in South Texas that threaten an annual agricultural economy estimated at $887 million. In February 2024, South Texas’ last sugar mill shuttered, heralding the death of an industry—the blame for which many have laid at the feet of Mexico for failing to meet its 1944 treaty obligations.
But the Rio Conchos also flows as the lifeblood for hundreds of thousands of northern Chihuahua residents. They tap the river and its associated groundwater for domestic use. They turn to the Rio Conchos as a ribbon of wildlife habitat in an otherwise parched desert. And they depend upon the river for a regional economy propped precariously atop irrigated agriculture.
La Boquilla Reservoir (Eduardo Talamantes)
Trapped between the treaty and the drought, many Conchos Valley residents find themselves in an increasingly dire situation. As one Mexican farmer told me, “When the water goes down, everything goes down with it.”
Amid growing tensions and looming uncertainty, a question lingers over the Texas-Mexico borderlands: What’s going on upriver, in Mexico’s Rio Conchos watershed?
Seeking answers, I traveled for three weeks up the Conchos Valley in the summer of 2022. I returned to the region—known in Chihuahua as the Centro Sur—in the fall of 2024 and lived there for three months. During these visits, I interviewed dozens of farmers, water managers, fishermen, river advocates, and everyday residents. Many told me they would fight for their water to the very last drop. Others, however, have already begun asking the existential question: Where will we go when the river runs dry?
On a 96-degree day in late May of 2022, I drove with Eduardo Talamantes down an agricultural backroad paralleling the Rio Conchos. A photographer for the City of Camargo, Chihuahua, Talamantes insisted that I take a look at a place called Las Pilas, a set of large diversion gates that lay across the river near the municipality of San Francisco de Conchos, not far from La Boquilla Reservoir.
“Las Pilas will give you a clear picture of what’s going on here,” Talamantes told me as the dirt road guided us through rural villages of adobe churches and cinder-block homes.
Arriving, we parked beside a bridge and looked upriver at a swollen, fast-flowing stretch of the Rio Conchos. It was surprising to see so much water in a landscape famous for its aridity. The river corridor was lush with willows and cottonwoods. But when all that water reached Las Pilas, the diversion gates shunted its flow into a concrete-lined canal. This canal, about the width of two school buses parked end-to-end, is known as el canal principal. Just below the headgates, the Rio Conchos dried entirely, its full flow having been carried off.
Talamantes pointed across the bridge at two wrecked pickups discarded near the canal’s rim. In 2020, these trucks were set ablaze, burnt to a crisp, and left to moulder in the blistering sun. “Right on this bridge,” Talamantes told me. “This is where the showdown happened.”
He referred to a rebellion that erupted across the region in 2020. The protests pitted thousands of Conchos Valley farmers against the Mexican federal government and Guardia Nacional in a conflict over international waters. At Las Pilas, the standoff involved farmers fighting to open the canal’s headgates so that water would flow to their pecan and alfalfa fields, instead of down the Rio Conchos and onward to the U.S.-Mexico border.
Talamantes had been there that day, photographing the upheaval. He told me farmers and National Guard members clashed on the bridge, bodies pounding against thick plastic shields, bottles of flaming gasoline hurtling through the air.
Protesters throw rocks in 2020. (Eduardo Talamantes)
Las Pilas was but one flash-point in a wider conflagration that engulfed the entire Centro Sur region. The 1944 Water Treaty sat at the center of the rebellion. Every five years, the treaty requires Mexico to deliver 1.75 million acre-feet of water to Texas. That works out to about 350,000 acre-feet a year. The treaty stipulates that Mexico make its deliveries down six named Rio Grande tributaries—the Conchos, San Diego, San Rodrigo, Escondido, and Salado rivers, and the Las Vacas Arroyo.
In 2020, the last time that water was due, farmers from northern Chihuahua’s sprawling irrigation districts took to the streets with sticks and Molotov cocktails. They burned buildings in Delicias and Camargo. They flipped trucks and set them ablaze. One protester was shot and killed. Others were wounded when members of the National Guard opened fire at Las Pilas, not far from where we were standing. The farmers nevertheless seized control of La Boquilla Dam and occupied it for weeks, staring down armed officers and forcing Mexico to find its treaty waters elsewhere.
In the years since 2020, the core issues that sparked the unrest—drought and treaty obligations—have persisted. Mexico’s water bill comes due again this year. But this time, the nation is even deeper in arrears. As of April, more than four and a half years into the five-year delivery cycle, the country had sent only 28 percent of its treaty water.
That same month, the borderlands water crisis caught the White House’s attention. President Donald Trump accused Mexico of “stealing water” in a social media post and threatened to punish the country with higher tariffs if they didn’t pay down their water debt.
In response, Mexico announced a joint agreement with the United States to transfer reserved water to Texas held in the binational Falcon and Amistad reservoirs, which respectively bestride the Rio Grande near the Starr-Zapata county line and Del Rio. Mexico also promised through October to give the United States half, rather than the typical third, of its water flowing down the Rio Grande and the six key tributaries.
With these concessions, Mexico will still likely end this cycle about 800,000 acre-feet in arrears, the largest water deficit Mexico has carried from one five-year cycle to the next since the 1990s. That’s why Texas continues to pressure the region to send the rest of the water owed.
When I returned to the Rio Conchos region in the fall of 2024, I assumed the Valley’s farmers would be ramping up for another fight. If water deliveries were further behind than during the 2020 protests, surely the Centro Sur was set for a repeat bout of civil unrest.
As it happens, my assumptions were wrong. Farmers had no plans to protest. They told me there was no need. I would learn this was largely because drought had already done away with what prompted the rebellions in the first place: water.
The headquarters of SRL Unidad Conchos, where I sat down with Rogelio Ortiz, occupy a peach-colored building in an agro-industrial zone of Delicias, Chihuahua. Until early 2025, Ortiz was director of the group, an agricultural association for Distrito de Riego 005, the state’s largest irrigation district.
Ortiz explained that Delicias, home to about 150,000, was founded in the 1930s as an “agricultural city.” The irrigation district and the city were “born together,” he told me, linked by a project that would harness massive, centralized water infrastructure to generate a productive agricultural class in Mexico’s northern deserts.
El canal principal effectuated that vision. The canal delivers 95 percent of the Rio Conchos’ flow to an estimated 10,000 farmers in Ortiz’s water district. These farmers plant more than half a million acres of irrigated desert in water-intensive crops like alfalfa and pecans, as well as other staples such as chiles, cotton, onions, wheat, and sorghum.
When I first spoke with Ortiz in 2022, it was less than two years after the Valley’s farmers had scored their costly but emboldening victory with the water protests. At the rebellion’s climax, the Mexican federal government acceded to farmers’ demands. Instead of delivering water from the Rio Conchos, the country had allocated its share of treaty waters far downstream on the Rio Grande.
To enable this, the International Boundary and Water Commission (IBWC), which oversees these deliveries, enacted an amendment to the 1944 Treaty known as Minute 325. Minute 325 allowed Mexico to transfer to Texas a large volume of its water stored in the binational Falcon and Amistad reservoirs.
With this move, Mexico made good on its treaty obligations while keeping water in the Centro Sur region for farmers. But it also dried up large segments of the Rio Grande, including the stretch through the iconic Santa Elena Canyon in Big Bend National Park. Even more concerning from Mexico’s perspective, transferring all that water jeopardized the country’s ability to ensure adequate water supplies for communities below the binational reservoirs in Tamaulipas and Nuevo León.
Left: Ortiz visits canal 005. Right: Irrigation canal 005 runs dry. (Eduardo Talamantes)
Ortiz maintained that Conchos Valley farmers were justified in withholding deliveries to Texas. The waters contained in La Boquilla and Francisco I. Madero—a smaller reservoir on the Rio San Pedro, a tributary of the Rio Conchos—are not designated “treaty waters,” he explained.
“The water from the dams—that stays here,” he said. “It doesn’t go away. The problem in 2020 is that they wanted to take it out of the dam. And there, yes, there is a problem.”
This interpretation, widespread among farmers in the Centro Sur region, maintains the treaty only has jurisdiction over “aguas broncas” or “wild waters.” This refers to water that seeps or spills from northern Chihuahua’s reservoirs, water generated by rainfall below the Mexican dams, or water that returns to the Rio Conchos as irrigation runoff.
Under that theory, Rio Conchos irrigation districts had full rights to most water stored in their reservoirs, Ortiz told me, and the Mexican federal government had no power to force them to deliver that water to Texas.
Mexico has typically relied on the Rio Conchos for making between 55 and 87 percent of its obligated treaty water deliveries, depending on the decade. On the one hand, this frustrates many Conchos Valley farmers. The Mexican government, they argue, unfairly forces them to pay the lion’s share of Mexico’s water debt. On the other hand, the Rio Conchos is the largest tributary in the entire Rio Grande watershed. If that source dries up, as is rapidly occurring, it’s difficult to see how Mexico could stay in compliance with the treaty.
In July of 2024, I put the question of the Mexican farmers’ treaty interpretation to Maria-Elena Giner, who was IBWC commissioner until this April. Was it true that water captured and stored by Mexico’s dams could be withheld from the treaty?
Giner recognized what had long been the Rio Conchos farmers’ interpretation. “The only way they deliver water to the United States,” she said, “is basically water that spills over the reservoirs.”
But she also explained that this view of the treaty was increasingly problematic: Climatic conditions have changed, and Mexico can no longer rely on aguas broncas for deliveries.
The most recent five-year stretch, 2020-2025, offered a case in point. Mexican agricultural interests “were able to capture the water,” she told me, “but they should have delivered more. And they didn’t. So now, we’re here.”
And where is “here?” Much like La Boquilla, Falcon and Amistad reservoirs have reached record-low levels. Mexico, as of late April, owed the States about 1.21 million acre-feet of water. Mexico could carry some of its deficit into the next five-year cycle, but the postponed debt would become enormous.
These problems have come to a head in the Conchos Valley. Time and again, I asked farmers and water managers whether they would willingly make their 2025 deliveries to Texas. They threw up their hands in what amounted to a collective shrug: “With what water?”
Sergio Ogaz, conservation coordinator at SRL Unidad Conchos, told me La Boquilla was so low there would be no 2025 irrigation season for district farmers at all. No water for Mexico. No water for Texas.
“We’ve had only one year where irrigation was restricted to zero,” Ogaz said. “And that was 30 years ago.”
That year, 1995, looms large in farmers’ memories. Not only does it mark a time when crops failed and the local economy sundered; it also reminds people of when their communities changed, and their families separated as their loved ones traveled off in search of other ways to make a living.
In Santa Cruz de Rosales, five miles west of Delicias, Alonso Márquez climbed down from a dually pickup truck hauling a trailer full of chiles and invited me to join him at a dusty desk in an office at the back of a barn. A manager on a 250-acre farm, Márquez told me the operation employed about 55 people.
“Now,” he lamented, “they’re telling us we won’t get any water. And if there’s no water, we can’t plant. And if we can’t plant, we can’t pay our employees.”
Agriculture accounts for 90 percent of the Conchos Valley economy, fetching an estimated $400 million annually. But it also consumes 89 percent of the water used in the state. The Centro Sur region’s economic base thus runs on water—a quickly vanishing resource. “Many people think it only affects those of us who work here,” Márquez said, “but people in the city are also impacted. If we don’t make money here, nobody goes to the restaurants to eat or the stores to buy.”
“Undocumented migration was most likely from areas experiencing extreme drought.”
Márquez’s comments touched on a recurrent theme across dozens of interviews. So tightly coupled was the economy to agriculture, and so heavily dependent was agriculture on water, that the drought had already begun to insinuate itself into all segments of society, affecting people from all walks of life. “It’s the fertilizers, the machinery, the mechanics to fix the tractors, the seed sellers—all of that,” Márquez said.
And the ramifications rippled beyond even the secondary farming services. For example, Montañez, the fisherman at La Boquilla Reservoir, introduced me to representatives from four fishing cooperatives. These cooperatives include about 130 families who live off selling fish they catch in the reservoir. As drought and agricultural extractions depleted the vast lake, fisheries collapsed. Their daily catches became so sparse they could no longer afford the gas it costs to power their trucks and boats.
Meanwhile, their settlements, which used to line the edges of the lake, were left stranded miles from shore. These villages—El Sepulvedeño and El Toro—used to draw domestic water directly from the lake. Today, the lake has receded so far they no longer have access to water for basic household needs.
A similar crisis threatens residents of Boquilla, the colorful, touristy town at the foot of the dam. Boquilla takes domestic water directly from the reservoir. But lowering lake levels began contaminating their water supply with sediments that have collected at the bottom during the lake’s century-long existence. In the fall of 2024, several residents turned on their taps for me, showing dirt-filled water the color of café con leche.
Back in the barn in Rosales, Márquez told me he had only seen one year as bad as this. “I was very young,” he said. “It was before I worked here. It was in ’95. Nothing was planted that year either.”
Márquez grew up in a small village of some 500, a “pueblito” known as La Garita. During the debilitating droughts of the mid-1990s, the work dried up along with the water, and La Garita emptied out. Márquez estimated half the population migrated to “el norte.” Many homes in La Garita remain abandoned.
“There are many, many small towns here where the people have already gotten their papers and are there [in the United States],” Márquez told me. “When there’s no work, you have to look for something. And those of us who stay here, well, we stay here talking. I talk at home and the subject [of migration] comes up.”
Migrating north represents a well-worn path in the Centro Sur region. Since farmers possess property and can prove a long-term income, many can obtain temporary visas. With these, some travel to work during the irrigation off-season in dairies, construction, or Texas oil fields, and they use their earnings to invest in their farms back home.
Prolonged drought likely intensifies this trend. A 2022 study published in the Proceedings of the National Academy of Sciences connects climate change with rising migration from agricultural regions in Mexico. “Undocumented migration was most likely from areas experiencing extreme drought,” the study concluded, “and migrants were less likely to return to their communities of origin when extreme weather persisted.”
Grappling with the region’s unrelenting drought, the IBWC recently adopted novel—and controversial—changes to the 1944 treaty.
As written, the treaty obligates Mexico to deliver 1.75 million acre feet every five years. But it also contains an “extraordinary drought” provision that allows the nation to carry over a water debt into the next five-year cycle. In other words, whatever amount Mexico owes by October of this year, the close of the current five-year cycle, could be paid off in the next five-year cycle, which concludes in 2030.
After months of negotiation, the IBWC in November passed Minute 331, an amendment to the treaty that granted Mexico more flexibility in the timing and sources of their water deliveries. Prior to Minute 331, Mexico could transfer water out of Falcon and Amistad reservoirs, but only during the next five-year cycle. Minute 331 allows Mexico to make those transfers during the current cycle. As a result of this change, South Texas farmers could begin receiving transferred water during the present irrigation season, as opposed to having to wait until October.
During past droughts, Mexico has sometimes tapped two rivers in addition to the six Rio Grande tributaries mentioned above: the Rio San Juan and the Rio Alamo. The new amendment allows Mexico to begin delivering water from those rivers immediately, without having to wait for the next cycle.
The IBWC contends Minute 331 will make Mexico’s deliveries more reliable and predictable. But the negotiations have rankled South Texas irrigators who say the change doesn’t go far enough to ensure Mexico delivers in full.
“Mexico is in a drought,” said Anthony Stambaugh, general manager for Hidalgo County Irrigation District No. 2. “That’s accurate today. But that wasn’t true for the whole five-year cycle.”
In 2022, a major storm system traveled up the Rio Grande corridor, unleashing torrential rains that filled Mexico’s dams to capacity. But the country did not take that opportunity to send water to Texas. “We only got what they couldn’t capture in their reservoirs,” Stambaugh said.
Rosa Elva Muñiz Meza of Julimes (Eduardo Talamantes)
Moreover, the San Juan and Alamo rivers reach the Rio Grande too far downstream to be captured by Starr County’s Falcon Dam—at the western extreme of the Rio Grande Valley—meaning downriver farmers in Hidalgo and Cameron counties contend they cannot capture that water for irrigation, even though Mexico is credited for delivering it. IBWC hydrologists pushed back against that claim in a December citizens forum, saying water from these rivers can be retained at Hidalgo County’s Anzalduas Dam, but Stambaugh told me that is a diversion dam not meant for irrigation storage.
For all the blame and attention placed on Mexico’s Rio Conchos, South Texas water depletions reflect a much broader, binational problem, ex-IBWC Commissioner Giner said. “In South Texas, they’re so focused on Mexico’s water [rather than water from Texas tributaries] because that’s the only number they know.”
To counteract this, the IBWC recently launched a binational water-accounting effort. The program measures all tributaries whose waters make it into Falcon and Amistad, thus giving water users a fuller panorama.
Even in the wettest of the past four decades—1981-1990—the Rio Conchos never contributed more than 16 percent of the water allocated to the United States at Falcon and Amistad reservoirs, according to IBWC data.
That same data shows a steady downtrend in volumes from all sources over the last 45 years, including important U.S. tributaries of the Rio Grande such as the Pecos and Devils rivers, as well as numerous unnamed springs and tributaries in Texas.
“In South Texas, your problem is not just Mexico’s water,” Giner said. “You’ve got a lot of problems with U.S. tributaries, too. And so, they really need to coalesce [in South Texas] and find those efficiencies.”
To enter the Mexican pueblo of Julimes, you drive across a high bridge that spans the Rio Conchos above an open dale of flood-irrigated pecan orchards and hayfields. In 2022, I met with a group of women there who had established a civil association around the defense of agricultural water.
Calling themselves “Las Adelitas,” the group formed in the throes of the 2020 rebellion. Their name popularly describes women who fought to support the Mexican Revolution in the early 1900s. “La Adelita,” a famous Mexican folk song, was likely inspired by a real woman fighter from Juárez. By 2024, the group from Julimes had changed their name to “Las Valentinas,” after another revolutionary woman. These Valentinas linked their struggle to keep water in Mexico to the romanticized ethos of the revolution.
“My husband had to migrate to the U.S.,” said Rosa Elva Muñiz Meza, a Valentina. “I was left here with everything. I was left with the children in school, with what little we planted, and with the dairy cows—which is what we lived on.”
Muñiz’s husband migrated in the 1990s, because the drought had gotten so bad the family feared they would lose their farm. Like many emigrants from the Centro Sur, her husband never intended to permanently leave. Muñiz emphasized: He was migrating in order to keep his family in place.
Her husband has since returned. But the dairy portion of their farm has shuttered. Now, both her young-adult children reside north of the Rio Grande. “Those of us who live here have a lot of family who’ve migrated,” Muñiz told me. “A lot. It’s how we get ahead, how we sustain ourselves. But it’s also very hard to live apart.”
Migration and the fight to defend water are cut from the same strategic cloth, said Eliza Cardona, a Valentina from Julimes. Farmers seek to cling to their land, their lives, and their tenuous place in a drought-stricken world.
“We separated our families for years,” Cardona said, “but this is how many small farmers have survived. Now, they want to take away our little pieces of land, where we have worked, where we have endured. So, you can imagine our fight for water: With teeth, shovels, sticks, and rosaries, we fight those who want to take from us.”
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