This summer, the Rio Grande dried up in places that it never had before. For more than 100 miles through wild and scenic country, its snaking, sandy bed cradled only a series of warm, stagnant pools. 

In the canyons of Big Bend National Park, visitors gawked at the conspicuous absence of the Great River whose arching path gives this rugged region its name. 

Out here in the quiet desert, it’s easy to forget this meek waterway supports 6 million people in two countries. Vast distances hide the relationships at play. 

Go 150 miles upstream from the canyons of Big Bend, up with Rio Conchos and you’ll find the sprawling orchards of Chihuahua State, Mexico, population 3.7 million.

Go 500 miles downstream and you’ll hit the Rio Grande Valley of Texas, with 46 bustling cities and towns, a billion-dollar agricultural sector and 1.3 million people—even more live across the river in Mexico.

Just over a century ago, this was a rolling, sometimes raging waterway, swelling in regular cycles to smash through canyons and swallow landscapes from horizon to horizon as it flows from snowy mountains 1,890 miles to the sea. 

When this once-mighty river showed its cracking bottom in the distant desert this May, it flashed a critical warning of conflicts and shortages ahead for the growing populations in both Texas and Mexico that depend on its dwindling supply. Indeed, by July the largest reservoir that relies on its flow had surpassed its record low. 

“The impact is coming very quickly,” said Maria-Elena Giner, commissioner of the International Boundary and Water Commission, a small federal agency assigned the big business of sharing the Rio Grande and Colorado with Mexico. She was addressing worried irrigators in far South Texas, a world away from the canyons of Big Bend who gathered  in late July for a town hall meeting to help prepare for shortages that were creeping down river. 

What many Texans don’t realize is that these farmers, like everyone in the booming Rio Grande Valley, rely on water that flows out of Mexico. They do so thanks to a 1944 U.S.-Mexico treaty, which requires Mexico to send water from its northern mountains to Texas farmers in five-year cycles (in exchange for U.S. water from the Colorado River at the Baja California border). 

When the river dried up in the canyons of Big Bend, it happened because Mexico wasn’t sending any water. 

“Only about 14 percent of Mexico’s water deliveries have been made,” said Giner, at the town hall in Weslaco. “There’s a real issue going on right now and we recognize that.” (Giner understands cross-border issues better than most Texans: She grew up in Ciudad Juarez while attending school in El Paso.)

In Texas, 70 percent of the water in the river comes from the mountains of northeastern Mexico, where years of deepening drought have already reached crisis levels. Mexico’s third-largest city, Monterrey, which depends on other rivers in that region, already is rationing water. Hundreds of miles away in the north Mexican state of Chihuahua, deadly clashes broke out in 2020 over authorities’ attempts to ship water to Texas, as the treaty requires. Since then, Mexican authorities haven’t tried to come up with the water that is owed, but that debt comes due in 2025. 

As the floodgates on north Mexican dams have stayed closed, spigots in the RGV have largely remained open. As reservoirs approach their record lows, that’s about to change. 

“Irrigation users have really been subject over the past several months to curtailments and cuts,” said Bobby Jankecka, a commissioner with the Texas Commission on Environmental Quality, which manages the Rio Grande. “That horrible reality is now about to expand. Our municipal, our industrial and our domestic users are now going to be prepared to face those sorts of curtailments.”

This problem didn’t sneak up on anyone. More than a century of development has sliced the wild river into pieces and hemmed it into the narrow ditch it occupies today. Because of New Mexico’s water rights, Rocky Mountain snowmelt hasn’t hit South Texas in 80 years. Below El Paso, a 200-mile stretch has run dry regularly since the 1980s.

At the river’s end in the Valley, close calls have come before, all since the mid-1990s. Each time, big storms saved the day. 

“Whenever we start talking about water scarcity it seems to rain just in time to put it off for a little bit longer,” Xochitl Torres-Small, undersecretary for rural development at the U.S. Department of Agriculture, told Valley farmers in this summer’s town hall. But that won’t work forever.

“We can’t put it off for a little bit longer right now,” she said.

‘Pumps and Motors’

Most of this problem comes down to the Rio Conchos, the largest single water source and, effectively, the Texas’ river’s headwaters. It flows—or lately, it doesn’t —from the Western Sierra Madre of Chihuahua into the Rio Grande between Ojinaga, Mexico, and Presidio, Texas. 

Today a meek Conchos dribbles into the Rio Grande’s dry bed in a dusty, yellow grassland. Farmers around here grow mostly hay now.  

Yet, this valley used to teem with muddy wetlands, back when the two rivers that nursed it were mighty. Spanish explorers in the 16th Century dubbed it La Junta de los Rios—the Meeting of the Rivers. They found some 10,000 people in a dozen villages of two-story mud brick homes raising crops along a 50-mile stretch of fertile floodplain.

“This has been farming country for thousands of years,” said Enrique Madrid, an Indigenous historian with long gray hair and a mustache, adjusting his glasses as he thumbed through his published English translation of Spanish explorations here.

As he speaks, Madrid, the son of the town librarian, pulls books and binders from tall shelves and stacked boxes that fill the living room of the small home where he’s lived all his life in the one-road town of Redford, population 23. (It’s seen better days, he said.)

He flips to an illustration of when his own ancestors tended fields along the rivers’ muddy banks but built their homes a safe distance away. Then he scans his shelf, picks out the Journal of Big Bend Studies, Volume 8, 1996, and finds his entry, “Native American and Mestizo Farming at La Junta de los Rios,” about how farmers here used the natural rhythm of epic floods to channel water through earthworks to their crops.

This place, like the rest of the Rio Grande, wasn’t part of the Republic of Texas that seceded from Mexico in 1836. Only after the U.S. invaded Mexico did it annex the river’s northern bank in 1848, along with all the southwestern territories, including the Rio Grande’s headwaters in Colorado and New Mexico.

After that, the days were numbered for traditional farming in La Junta de los Rios, and for the ancient floods that sustained it. Enterprising immigrants poured in. Railroads brought people and heavy machinery—not just here but upstream in New Mexico and down the Valley as well. 

“The Anglos brought in pumps and motors,” Madrid said, chuckling in his worn-out armchair. “They think they can do better than all these poor people who’ve been here 20,000 years.” 

Soon, hundreds of wood-fired pumps were drawing water onto new orchards and fields far upriver in New Mexico and Colorado. By 1916, a massive dam was built to catch Rocky Mountain snowmelt in New Mexico before it rushed into Texas. 

Just like that, La Junta de los Rios was gone, its northern arm severed, the floods that nursed its wetlands over. The old Rio Grande was broken in two—one river that flowed from the Rockies to El Paso and a second Rio Grande that flows from the Rio Conchos, through Texas to the Gulf.

For the century since, the Conchos alone has watered this valley. Mechanical pumps enabled farming without floods. But little by little, the Conchos faltered, too. Mexicans built dams and planted orchards in Chihuahua, as well. This summer, the Conchos stopped running altogether, turning its path through the old Junta de los Rios into a muddy trench.

In the town of Redford, a farmer and retired Customs and Border Protection worker named Esteban Mesa peered into the shallow water where his irrigation pump tapped the Rio Grande, 15 miles below the mouth of the Conchos. He said he had never seen it so low.

“The climate is changing,” Mesa said as temperatures exceeded 100 degrees during late morning in May. “I feel the heat of the sun more.”

He recounted the recent rains here—three-quarters of an inch back in June 2021 and four-tenths of an inch that October.

“I don’t know what’s going to happen,” said his wife, Josefina, who grew up in Redford when agriculture thrived. “When there’s no water, what can you do?”

Madrid, the local historian who lives down the street, thinks he knows.

“All the cities on this river are going to fight for the water,” he said.

‘I’ve Never Seen It So Dry’

This dry spell spreads far beyond the old Junta de los Rios. Across a swath of North America, scientists have identified more than two decades of unusual dryness, as wilted cactus in the Chihuahua Desert attest.

About 150 miles downstream from the mouth of the Conchos, a 74-year-old retired backcountry firefighter named Guadalupe Davila points out where his own tiny village of Boquillas used to grow its food.

“All this used to be full of crops,” he said, standing atop a rock ledge and waving his hand over the sandy desert valley. 

The crops grew thanks to rain that fell in the Sierra Madre to the south then rushed past Boquillas on its way to the Rio Grande. A network of crumbling canals built by local families show how they formerly channeled pulses that washed down the mountains into fields of corn, beans, squash, tomatoes and chiles.

That was almost 30 years ago. Today, no gardens remain. One man raises hay on what little water still arrives, Davila said, pointing to a distant greenish-tan patch in the sand. For the most part, people gave up in the late 1990s. Too many dry years wrecked farmers’ labors and investments. Even though wet years have come, the rain isn’t reliable anymore. Now, a truck comes to town once a week selling produce.

“I’ve never seen it so dry like it is now,” Davila said as he scanned the parched valley. “There’s no grass.”

‘The Bucket is Almost Empty’

After Boquillas, the Rio Grande squiggles through about 220 miles of wild canyons and pristine, sparsely-inhabited country until it hits the dam that forms the Amistad Reservoir. Here, the free-flowing river ends for good. Afterwards, its flows are man-made.

This dam, completed in 1969, spans six miles to catch the floods that roll down the river and store them in its massive lake, from which millions drink.

This “lake” is like a giant bank, holding the accounts of hundreds of downstream users – cities and irrigation districts in Texas and Mexico (where all water is owned and managed by the federal government). The banker—the TCEQ Rio Grande watermaster—knows exactly how much each user has in each account. When a user wants to make a withdrawal, they ask the watermaster. When new water flows into the lake, the watermaster divides it up, giving priority to municipal users and state reservers.

Lately, not much water is flowing in. Amistad is 29 percent full—lower than it’s ever been. Its downstream counterpart, Falcon Lake, is at 14 percent. Communities there have asked the state to help extend pump intakes to reach its final dregs.

Yet from the gates of Amistad, water still rushes forth, past a half dozen cities of the Middle Rio Grande, which so far seem reluctant to confront the mounting crisis.

“The bucket is almost empty,” said Martin Castro, Watershed Science Director with the Rio Grande International Study Center in Laredo. “We’re heading towards a point of no return.”

‘We Need Help’

Laredo forms part of the largest metro area on the Rio Grande below the Conchos. Founded in 1755, it’s better known today as “los Dos Laredos” since U.S. annexation converted the river into an international border. About 260,000 people live in Laredo, Texas, and another 425,000 across the river in Nuevo Laredo, Tamaulipas.

Leaders there are aware of upcoming shortfalls. Laredo owns rights to pull 61,825 acre-feet, about 20 billion gallons, from Amistad each year. In 2021, the city’s 50-year water plan said its population would outgrow the water supply by 2040. Its top recommendation: run a pipeline between 70 and 150 miles to an aquifer in another county and import tens of millions of gallons of water per day. Laredo has 18 years to make that happen.

“The river, we cannot rely on it any longer,” Castro said from the Rio Grande study center, which is housed near the river in a former U.S. Army base built in 1849, the year after the United States claimed this northern bank.

Yet the city has no means to pay for an alternative water source. At a recent meeting of the Laredo city council, mayor Pete Saenz said the city desperately hoped for federal funding from the recent infrastructure bill in order to make the water pipeline happen.

“We need help. We cannot do it alone locally. It would throw us into a horrendous financial bind as a community for us to try to attempt to bring water,” Saenz told the council. “If somehow the state says no, we have no choice. We’d have to suspend basically everything that we have just to address that supplemental water.”

Tricia Cortez, the study center’s executive director, believes that the city’s 2040 timeline may be overly optimistic. Its projections only consider population growth, and do not take into account that drying and warming trends identified in this region will continue to deepen, she said. They assume a constant climate that no longer exists.

If the drying trend persists, Laredo has even less time to find more water.  

“No one is coming to figure it out for us,” Cortez said. “There is no institution taking the lead on adapting to these big changes that are coming.”

For many people, the crisis seems easy to miss—as evidenced by the 10 million gallons of water Laredo sprays on its lawns everyday. To the untrained eye, the robust river rushing each day under bridges between the Dos Laredos creates the impression of a strong water supply. But that’s only an illusion.

This is not just water in a free-flowing river. It’s a commodity in a giant irrigation ditch, and every last drop is spoken for. That water leaves Amistad in a steady sequence of meticulously measured releases, bound each time for specific downstream customers. As such, the river levels in Laredo may even rise during drought, as downstream farmers order more water to offset dry soils.

It’s bound for the thirstiest users in this entire system: the lush cropland and sprawling boomtowns of the Lower Rio Grande Valley in Texas.

‘The Magic Valley’

About two hours’ drive south from Laredo, the highway dips from yellow grasslands into the vibrant green of irrigated fields and orchards.

This broad, low floodplain runs for some 70 miles until it meets the sea at Laguna Madre. Although it is known as the Valley, the Rio Grande Delta would be more accurate. Here the river used to rise above the low hills that crest the Valley and spill floods from distant mountains into a shifting array of tentacles that spread out towards the sea. Water almost always abounded. 

Yet unlike the old Junta de los Rios, more than 600 miles upstream in the desert, the delta was never a historical hub for agriculture. The farming way of life here is relatively new, dating to the 20th Century.

Before Spanish times, native people kept their distance from the raging river, whose thrashing course often wiped out any village or farm within miles. Dry land one day could be marshland the next. The water’s invasions came in floods roaring down the great river, and in hurricanes roaring up from the Gulf. Semi-nomadic groups made seasonal visits, but the climate was unwelcoming, said Francisco Guajardo, director of the Museum of South Texas History in Edinburg. “This place was not a desirable place to live.”

The Spanish founded ranches along the Rio Grande starting in the 1700s. Tejano cowboys grazed enormous herds of Iberian cattle on the open range for more than a century before the U.S.-Mexico war brought this land under Texan control.

After that, eager entrepreneurs swept in and saw the potential that pumps and motors could bring to this fertile floodplain with seemingly limitless water. When a Wisconsin-born farmer’s crop of Rio Grande sugar cane won first prize at the 1904 World’s Fair, the rush was on.

“The Rio Grande Valley comes to be branded as the ‘Magic Valley.’ So all these land development companies begin to import all these palm trees from the Caribbean Islands,” Guajardo said. “You have a windfall of investment in an agricultural economy.”

Midwestern developers bought up massive tracts and imported pumps the size of houses, powered by heaping cords of firewood, to spread water across a million acres of alluvial soil and grow premium tropical crops like citrus and sugarcane, plus all kinds of vegetables. Fast-growing cities followed: McAllen, Edinburg, Pharr, Harlingen, Weslaco—all founded after 1900. 

Back then they pumped freely from a rushing river. Today it’s a different story. 

“We just don’t have the kind of water to be able to do a whole other century worth of agriculture,” Guajardo said. “Something has to give.”

Agriculture has declined in recent decades, as U.S. distributors began looking to cheaper producers in Mexico and Guatemala. It’s still a cultural pillar for the community and a 1.1 billion dollar sector—far smaller than the Valley’s $7 billion consumer shopping sector. 

The advent of NAFTA and manufacturing in the border zone after 1994, the logistics boom, the burgeoning border security business and an inviting climate for retirees on a budget have all helped grow this line of farming towns into a solid strip of suburban sprawl lining 60 miles of roaring interstate highway. 

“We are a delta community that has not only forgotten, in many cases, but is oblivious to the river,” said Jude Benavides, an associate professor of environmental science at the University of Texas Rio Grande Valley. “Now it’s pretty much out of sight, out of mind for most people.” 

Former farmer Rusty McDaniel guesses that during the 18 years he’s managed Hidalgo County Irrigation District 1 in Edinburg, he’s watched two-thirds of its acreage turned from farmland to suburban development. At 73 with bright white hair, he said he’s the average age for a farmer here. Most are retiring—cashing out on family land for big bucks from developers amid a real estate boom. 

“Look at these homes. They’re all sold. This was just blank land,” said McDaniel, pointing out his office window at a brand new subdivision.

When McDaniel grew up here, the region fed itself with a surplus of fresh vegetables. Now most supermarket produce comes from far away. 

“The ag is going away,” he said.

With ag sales go water rights, signed over to the cities and their public utility departments. The region’s two largest Texas cities, McAllen and Brownsville, have both doubled in population since the 1980s. The third largest, Edinburg, has quadrupled in that time. And the growth isn’t stopping. 

In McAllen, about 60 percent of municipal water use goes to water lawns, according to Jim Darling, a former McAllen mayor and head of the Region M Water Planning Group.

“I’d say the average citizen has no concept of where the water comes from,” he said from his office atop McAllen’s Rio Grande Bank tower. 

Water planners, however, are keenly aware of the drought on the Conchos and of the low levels of Amistad, he said. They know that shortages are coming. 

“We’re praying for a hurricane,” Darling said, then corrected himself, sensitive to the region’s traumatic hurricane history. “For a benevolent tropical storm.” 

Timely rains have always saved the day before. September is peak storm season and the region’s wettest month. If this month disappoints, next summer will see unprecedented water restrictions. 

Despite the Valley’s suburban boom, irrigators still use most of the water. So, those restrictions will hit farmers first, and hardest. Already, some farmers are facing curtailments. 

“It’s starting to feel like a water shortage,” said Jose Silva, a citrus farmer and growth care manager for the Edinburg Citrus Association in July. 

‘Gonna Get Real Interesting’

In a green grove outside Edinburg, Silva parks his pickup truck beside a small pump station and a one-acre pond. Another similar setup lies nearby, and another can be seen in the distance.

Silva manages 1,500 acres like this for the ECA on behalf of investors, absentee owners and a few local farmers. He checks the notes on his clipboard. This pump ran the day before for 9.7 hours and moved 536,000 gallons into the little reservoir, from which it slowly dripped about 61 gallons at the roots of each tree in this 40-acre orchard.

“Those trees will just suck that water up pretty quick,” he said as he drove the rows and surveyed the sprinklers dribbling at each tree’s base. 

This efficient drip irrigation method is used on about 20 percent of the citrus fields here, he said. The other 80 percent still flood entire fields, using twice as much water. Historically, the water savings of drip irrigation haven’t mattered much to farmers here, who pay only $10 per acre-foot—about 326,000 gallons.

Even that’s changing for farmers like him, Silva said. In addition to the groves he manages, Silva raises his own 8.5-acre plot of oranges. His irrigation district, the Donna Irrigation District, is low on water and hasn’t been able to provide the irrigation he needs.

“It’s not a good feeling for me right now,” he said. “To be honest, we’ve never had to deal with this.”

The shortage has forced him to buy excess water from neighboring districts for $30 an acre-foot, three times what he usually pays (but well below the $1,000 his brother-in-law pays in California). Soon, however, he knows the other districts will need the water for themselves.

So far, at least, others have kept the spigots wide open for most of the groves that Silva manages.

“You look at these canals, you wouldn’t think there’s a water shortage,” he said as he passed a flowing irrigation ditch.

So far, seven of the region’s 32 irrigation districts have implemented restrictions.

Cameron County Irrigation District No. 2 imposed restrictions in April 2021. Back then, the district announced farmers were only guaranteed a supply sufficient for one full crop on their acreage. In September, the district dropped the figure to one-quarter of a crop. In January, it fell to three-tenths.

Manager Sonia Lambert said the district has imposed restrictions on users twice before, in 1999 and in 2012. Each time, they lasted only weeks before big rains broke the drought.  

“Never has it lasted this long,” Lambert said. “It’s a pretty scary situation, not knowing how long this is going to continue.”

Each district has its own threshold for restrictions. Cameron County No. 2 started early because it’s a big user. On the rural edge of the Rio Grande Valley, almost all of its farmers still flood fields, including sugar cane, the region’s thirstiest crop and one of the most water-intensive in the world. It requires up to 1.6 million gallons per acre per year during dry times. 

The more populous urban districts haven’t been affected. The largest urban water supplier, Hidalgo County Irrigation District No. 2, is still sitting on a healthy reserve, said its manager, Sonny Hinojosa. His district pumps water to cities like McAllen, Edinburg, Alamo, San Juan and Pharr.

“Should nothing change, we’re a year away from restricting,” he said, crunching numbers on a white board at his office in San Benito. 

Hinojosa, a veteran Valley water authority with a crisp white button-down tucked into dark blue jeans, has been through this before—in  2002. During two consecutive five-year cycles, Mexico had paid less than half the water it owed Texas farmers under the 1944 treaty—the first two times it had ever come up short. Rio Grande reservoirs sunk to record low levels.

“Mexico had the water and they just chose to use it instead of delivering to the U.S.,” Hinojosa said. “By the time we realized what happened, it was too late.”

Valley irrigators were losing crops, so they rallied and asked the state government for help. 

“Since there was no water to give us, instead they gave us money,” he said. 

But the crisis ended suddenly with heavy flooding in November 2002; the near years brought ample rain. By 2005 the reservoirs were nearly full. Years of plenty ensued. Big storms in the Conchos basin sent water gushing down the Big Bend canyons and into Amistad, which spilled over its brim in 2008 and 2010.

Then the wet years ended; 2011 was one of record drought. But Amistad was full, so Valley farmers watered through the dry years undamaged. From 100 percent in 2010, the reservoir plummeted to 30 percent by 2013, before rain in 2014 put it back over 50 percent.

During those years, Mexico fell behind on its water payments again. In 2015 it ended a five-year cycle 250,000 acre-feet in debt. By the next cycle’s end in 2020, Mexico was behind again. Even though its own reservoirs were low, the country faced pressure from the Trump administration to pay up.

In Chihuahua state, Mexican authorities opened the dam gates at La Boquilla, the largest reservoir in the Conchos basin, 150 miles from the Texas border, sending its waters into the Rio Grande.

Local communities protested the release of their water to pay debts to Texas. Two days after the gates were opened, a mob of farmers armed with clubs forced their ways into the dam facility and shut off the valve. Clashes with the Mexican national guard left two people dead.

So Mexico hastily devised a legal trick to pay off its debt, signing over rights to all of its water already stored in the Falcon reservoir. Since then, it hasn’t tried again to release water from La Boquilla, which is 28 percent full now 50 percent full after recent heavy rains.

“Mexico has overdeveloped their water supply,” Hinojosa said. “They’re farming desert land. They increased their acreage with water that should have gone to the U.S. And it was U.S. companies doing it.”

“It’s gonna get real interesting,” he said, leaning back into his leather chair. 

Farmers here have no idea how long they’ll have to wait for water from the Conchos. 

Mexico has until 2025—the end of this cycle—until it becomes officially delinquent on water payments. Even then, the 1944 treaty allows for one delinquent cycle—“in the event of extraordinary drought or serious accident”—to be paid up in the next. So Mexico has until 2030 until it would officially violate the treaty (which it previously did in 2002).

“Every time that Mexico falls behind in complying with the treaty, there is no question that Texas agricultural interests in the Rio Grande Valley are the ones that bear the most significant impacts,” said Carlos Rubinstein, former head of the Texas Water Development Board.

If Mexico violates the treaty, he said, “it’s up to the U.S. State Department to ensure it is honored.”

That could be done, Rubinstein said, by withholding water from the Colorado River that the U.S. owes Mexico. But no no one knows what would happen if Mexico’s debt comes due on water it simply doesn’t have.

‘Grave Consequences’

In the Sierra Madres of Mexico’s north, the river basins that feed the Rio Grande ran bone dry this summer after six consecutive years of low rainfall.

“Many of the rivers that used to be permanent, now they don’t exist,” said Oscar Leal, water program coordinator at Pronatura Noreste, an environmental nonprofit based in Monterrey, the largest city in northern Mexico.

With 5.3 million people, Monterrey is the third largest metro area in Mexico, and one of its richest. Like the Texas Valley cities, its population has doubled since the 1980s. There, authorities have been rationing water since June. Most households get water for just a few hours each morning—others not at all.

Through Monterrey runs the (mostly) dry bed of the Rio Santa Catarina, which later hits the Rio San Juan, which joins the Rio Grande downstream from both binational reservoirs, Amistad and Falcon, so its waters don’t contribute to the reservoirs that sustain South Texas cities and farmers, leaving it outside the U.S.-Mexico standoff.   

It’s the Rio Conchos, more than any other, that South Texas depends on to keep its reservoirs full. That river flows out of the vast state of Chihuahua, hundreds of miles from the Rio Grande Valley in the deserts and mountains that border West Texas. 

Chihuahua State boasts its own booming pollution and thriving, $3 billion agricultural sector, largely watered by the Rio Conchos system. Its eponymous capital city has a million people in its metro area. It, too, has doubled its population since the late 1980s. 

Pecan groves have become a major industry in Chihuahua. The state’s pecan harvest more than tripled between 2000 and 2017 according to the Mexican Commission on Nut Production. Today Chihuahua is the world’s second leading exporter of nuts, after the U.S. It is also Mexico’s top producer of apples.

One study found that the depth of irrigation wells for apple orchards in Chihuahua grew from an average of about 200 feet in 1980 to almost 1,600 feet in 2010 as aquifers levels receded.

It isn’t the first time that farming has boomed in these dry, fertile valleys, according to Marusia Renteria at the Universidad Autónoma de Chihuahua. The story of the last time around raises a grim specter for where the future may be headed. 

Seven centuries ago, the Paquimé civilization flourished in Chihuahua. Major works of water infrastructure enabled 3,000 people to farm with a great network of fields, canals, cisterns, reservoirs and drains, capturing and storing water when it rushed down surrounding mountains. They built multi-story stone cities and impressive public works. 

Then the mountain rains faltered. The Paquimé’s decline, Renteria said, lines up with a goliath dry spell from about 1350 to 1450. It was part of an era of drying thought to have brought several civilizations of the American southwest to their demise.  

Scientists call it a “mega-drought”—although some wet years come, too many dry ones make intensive farming impossible. 

By the time the Spanish arrived in Chihuahua, the Paquimé’s cropland had disappeared back into the desert. Their canals were abandoned, their cities crumbled and their civilization dispersed into wandering bands.

Today the farms and canals are back. This time 3.7 million people live in the state of Chihuahua. As years of recurring drought persist across this wide region and beyond, Chihuahuenses can’t help but ponder if this is another big drought that may force Mexico, a few years down the line, to choose between its own needs and its water debt to Texas. 

“We are legally obligated, between countries, to comply with the treaty,” Renteria said. “It’s risky to say it, but these are two countries we are talking about. There are grave consequences that this could bring.”