Why has the Colorado River Delta in Mexico dried up?

BAJA CALIFORNIA, Mexico — Manuel Machado Gerardo watched the mighty Colorado River Delta die perhaps more clearly than any man alive.

Taking the final drags from his cigarette, he steps outside his home to greet the 112-degree heat and survey the hundreds of acres of northern Mexico farmland he's owned for decades.

At 78 years old, he walks slowly with a limp and a slight hunch in his back. But he's surprisingly agile for his age, some youth preserved by his dry, witty humor and an insistence that he still work his farm, where for 56 years Gerardo has grown everything the fertile Mexicali Valley would allow.

Pushed up against the U.S. border in the Mexican state of Baja California, the Mexicali Valley houses the final 100 miles of the Colorado River. Thousands of miles of winding tributaries take snowmelt from the lush Rocky Mountains through the high country of Wyoming, Colorado and Utah and into the red rock desert of the American southwest, emptying into the Mexicali Valley and eventually the Sea of Cortez.

The reality is grim at the end of the river. The population growth, government policies and climate change that have brought the Colorado to its knees are palpable.

In Mexico, the river is a shell of its former self, in many places conveyed by concrete canals to bring water to farmers, while the natural riverbed goes dry. Tijuana, Baja California's largest city that relies on the Colorado River, is slipping further into crisis as entire communities are hit with random water blackouts. And advocates have little faith that the Mexican government and its rotating door of bureaucrats can deliver real solutions.

Yet for the second time in years, much of the river was alive again thanks to a recent treaty between the U.S., Mexico and a handful of nongovernmental organizations that allocated water to the ecosystem.

Water returned to parts of the river that had been reduced to dust, bolstering environmental remediation projects and giving communities in the Mexicali Valley a reason to hope.

Life was the same, but with water

Standing beside his nephew and godson, Gerardo opened a book — "A Photographic History of the Colorado River," the cover read, in Spanish — and flipped through several pages. He stopped at a black-and-white image of a steamboat, taken near present-day Yuma, Arizona, in 1876. Dozens of passengers stand on the deck, behind them what appears to be a large lake, or even the ocean.

"This was taken 20, 30 kilometers from (here)," he says, pointing north.

The demise of the Colorado River Delta began in 1944 when Gerardo was an infant, after the U.S. and Mexico signed a treaty allocating 1.5 million acre-feet of water south of the border. The river was still nearly 10 miles wide at some sections, spanning the rugged mountains west of the Mexicali Valley to Yuma, Arizona. Steamboats shuttled horses, then cars, from Mexicali to San Luis across the rich delta that jaguars, beavers, deer and coyotes once called home.

"On the map the Delta was bisected by the river, but in fact the river was nowhere and everywhere, for he could not decide which of a hundred green lagoons offered the most pleasant and least speedy path to the Gulf," wrote American author Aldo Leopold in 1922.

As a kid Gerardo would swim in the river's sprawling meanders and cook fish on its shores, sitting in the shade of the towering cottonwood trees that lined the riverbank. The years passed, and his childhood playground began to disappear.

With the treaty came a new approach to managing the river, and Mexican officials decided the 1.5 million acre-feet allotted to them would be used exclusively for human consumption, mainly agriculture, industry and municipal use. On paper, the ecosystem of the delta was now an afterthought.

Then came the Morelos Dam in 1950, and the Glen Canyon Dam in 1966. By 1980, the population of the American West had nearly tripled since the treaty was signed, with cities across the basin vying for a sip of the Colorado River.

The Mexicali Valley was also experiencing an agricultural boom, as farmers moved to the fertile sliver of northern Mexico.

"We could plant wheat, and immediately after the harvest we had to use the land because we had so much water. There was an abundance, the land here produced all year. We didn't have to stop at all," said Gerardo, who bought his first tract of farmland in the valley in 1964 when he was 22 years old.

"Life was basically the same back then, but with water," he said in Spanish with a wry smile.

By 1985, over 80% of the natural ecosystem of the Colorado River Delta was lost as more farmers flocked to the valley. A system of canals snaked through the desert, diverting nearly all the water from the Colorado. Decades of drought also started to take its toll as the river bed went dry and the water table started to collapse.

A few times each year, tides drove the Sea of Cortez through the delta and into the river — but the once lush expanse, where for thousands of years snowmelt from the Rocky Mountains emptied into the Pacific Ocean, turned to dust.

"It's sad. And it's people who are responsible," said Gerardo. "Mostly the government, they're responsible for the lack of conservation."

When asked about the future of the Mexicali Valley and whether drought and the government's policies will lead to its demise, Gerardo speaks with a cynical wisdom that comes from having a front-row seat to decades of climate change.

"I've seen the climate change, and the pollution of the seas. I might not (live to) see it, but it will be because of the lack of water. It's a huge problem. And it will get worse," he said.

In Tijuana, a river runs rancid

Now surrounded by the looming steel wall along the U.S. border, the Morelos Dam marks the beginning of the Colorado River's journey through Mexico.

From there, an estimated 20% of the country's allotted Colorado River water goes to Tijuana, home to 2 million people.

Running parallel to the U.S. border wall, a lone aqueduct pumps water across the barren desert north of the now dry Laguna Salada, climbing 3,000 vertical feet over the rugged Sierra de Juarez and through La Rumorosa, the mountain pass towering above the Mexicali Valley. The pipeline then empties into the Tijuana River, a mostly dry watershed.

The river and its tributaries wind down the high country before hitting a concrete canal on the outskirts of Tijuana, where roughly 5,200 liters of Colorado River water is conveyed every second. From the canal, the water is diverted to different areas of Tijuana through seven different pipelines, treated and maintained by the El Florido Water Treatment Plant.

The infrastructure that takes Rocky Mountain snowmelt on a 160-mile journey from the Morelos Dam to Tijuana is a magnificent feat of engineering. Yet it hardly addresses the pervasive issues in Tijuana that leave thousands of the city's most vulnerable residents without water.

"We're probably going to get the water cut soon. It could be any day," said Adriana Mendoza, a 22-year-old mother of three whose house is perched high above Los Laureles, a fast-growing, low-income community in northern Tijuana that consists of mostly rented land, with illegal squatters encroaching on the hillside.

"Monthly, they cut the water for a whole week, or sometimes two weeks, in different neighborhoods. Every month," Mendoza said.

The system is further strained by the city's rapid growth that doubled Tijuana's population since 2000. Every day, people from across Mexico move to the city, some fleeing violence or economic hardship, only to resettle in neighborhoods that lack reliable access to water.

"We have it on our minds all the time," says Jose Lopez, who moved to Los Laureles in May. "We have a regular life, a normal life, except we are thinking all the time about water."

The government delivers water to a single home about 200 yards from where Lopez lives. There, a jury-rigged system of white PVC pipe pumps water to a handful of other nearby residents, including Lopez, who uses a small garden hose to fill 50-gallon barrels that his family uses to clean dishes and clothes, and go to the bathroom. Technically, the system is illegal, but without it Lopez would have no water — he's tried, repeatedly, to contact the water authority since moving to Los Laureles, but gets no response.

"The government should come and see the way we're living our life. Because they always stay in their offices, they have no idea what's going on here. There's a big difference here from communities where there's money involved," Lopez said.

The neighborhood where Lopez lives is also not connected to a sewage system, and the creek that runs through the heart of Los Laureles is sometimes filled with untreated sewage that eventually empties into the ocean. Treating it would require funds that the government doesn't have.

"They're broke, the water authority has no money," says Margarita Diaz, a longtime advocate for pollution monitoring and water infrastructure. Her organization, Proyecto Fronterizo , has repeatedly undermined the government's messaging that the beaches are clean and the water is safe.

"I don't want to blame all the government, but it's a reality in Tijuana. They're short (on) resources, and there's a lot of people," she said, standing near the northernmost point of Baja-California's picturesque coastline, marred by perhaps the most visceral example of the water authority's financial woes.

Below the overlook, Diaz points to a raging torrent of raw sewage spilling into the ocean and turning the water around it brown and foamy, almost like an oil spill.

Diaz says there are 19 new communities in northern Tijuana — including some in Los Laureles, where Lopez lives — that are not connected to a sewage treatment plant and simply empty their waste into the watershed. Plus the treatment plant that would typically serve the area has been defunct since 2017.

If the city invested in a robust sewage treatment system, Diaz says that could both curb pollution, and provide running water to people like Lopez.

"A lot of these problems, they would be solved," Diaz says, wincing as the wind shifts and the stench of raw sewage overtakes the salty, ocean breeze.

The situation in Tijuana is prophetic, Diaz says. If Baja California doesn't make drastic changes to the way it allocates water while investing in new treatment systems, the problems that Lopez and his neighbors deal with could become widespread across northwest Mexico.

But despite her years of research that point to an increasingly unsustainable situation in Tijuana, she says government officials often respond with apathy.

"We won't have more water. It's going down and down, and it's frightening that (the government) isn't looking at this like it's a big deal," said Diaz. "Hello, it's water!"

Raising the river

The reality of the Colorado River in Mexico is at times bleak, and it's hard to fault the lack of optimism from people like Diaz. But back in the Mexicali Valley a few miles from Gerardo's farm lies a reason for hope.

"The last time I saw (the river) like this was 30 years ago," said Ricardo Mozqueda Martinez, a politician in the Mexicali Valley, on a hot June morning.

Martinez was one of dozens who showed up to a community cleanup day at the Vada Carranza Bridge, a community park situated on a picturesque stretch of the Colorado River.

Just a few years ago, the section of river was completely dry.

But as Martinez spoke, kids fished for smallmouth bass and catfish while hungry pelicans, grebes and herons flew overhead. Volunteers from the Sonoran Institute, The Nature Conservancy and other organizations picked up trash from the river's banks, before jumping in the water to escape the early afternoon heat.

In 2014, Mexico and the U.S. ratified Minute 319 , which allowed about 0.5 cubic meters each second to flow from the Morelos Dam through the natural riverbed and into the delta. By the end of spring, the pulse flow delivered 130 million cubic meters to the riverbed, briefly reuniting the Colorado River and the Sea of Cortez for the first time since 1998.

And roughly seven years later, the Colorado River was again reconnected with the delta, with another treaty between the U.S. and Mexico allowing water to be delivered to a number of restoration sites through a series of irrigation canals. Signed in 2017, Minute 323 permits Mexico to continue to store water in Lake Mead, funds restoration projects in the delta, and allows a surplus of water to be shared.

The first surplus delivery began in 2021 in the spring and summer months to mimic traditional runoff. And this spring, 765 liters of water each second again barreled out of a pipeline about 45 miles southeast of Mexicali City, filling parts of the dry riverbed and turning the beach near the Vada Carranza Bridge into a desert oasis.

Though the connection of the delta and the river was short lived — environmental groups say it lasted for about 24 hours in June — it was meaningful.

"When we started this, there was a lack of trust that this could even happen," said Edgar Carrera with the Nature Conservancy, who has been working as a biologist in the delta for the last decade.

The treaty is made possible by cooperation between the U.S. and Mexican governments, and a coalition of nongovernmental organizations called Raise the River that for years have been restoring the riparian zones along the delta.

At the south end of the Mexicali Valley is the Laguna Grande restoration site, perhaps the most visual example of the coalition's success.

In 2008, the area was a sorry sight — invasive salt cedar shrubs had choked out the native cottonwood trees, eliminating bird and mammal habitats, and decimating the soil health. The river's weak flow was unable to breach the sediment clogging much of its natural channels.

Today, it's a lush jungle, with massive cottonwood trees rising above the desert like a mirage.

The Sonoran Institute started by clearing out the invasive vegetation and planting native trees. They dug small channels diverting water away from the riverbed to restore the riparian soil health and create a dense forest along the river.

Over the next 10 years, the ecosystem rebounded. The number of bird species recorded in the area jumped from 50 to 350, feeding on the fish that returned to the river, while a small population of beavers moved in — Carlos Restrepo, a monitoring specialist for the Sonoran Institute, says "Laguna Grande is the last stand for the beavers in Mexico."

"We always take the water from the ecosystem, and this is the first time that we are working to put it back in. We don't want it, we want the river to have it," said Restrepo, standing in the shade of Laguna Grande's robust forest.

"You don't need to have the whole forest growing along the river to have benefits," he said, "but if you implement little patches or medium-sized patches, along the whole stretch of the river, you will see benefits."

The restoration of Laguna Grande, and a handful of other sections of Mexico's Colorado River, hasn't just brought back to the ecosystem — it's given new life to its surrounding communities, where many residents forgot the river ever existed.

"You watch it die, it disappears and you forget about it. But then older adults visit Laguna Grande and something clicks — 'this is where my dad used to bring me when I was a kid,' they'll say and then start crying," said Gabriela González Olimón. "It's so beautiful."

A biologist and environmental education coordinator for the Sonoran Institute, Olimón gives educational tours of Laguna Grande. She's hoping to get more funding for full-time park rangers and infrastructure for visitors so the site can operate as a national protected area.

"If you do this for 10 years in a row, certainly there will be beneficial effects for the ecosystem and the communities," Olimón said.

Still, there are farmers in the valley who think allocating water to the ecosystem is at odds with their industry. Back at his farm, Gerardo scoffs at that idea. The restoration, and the water flowing through the river, have his full endorsement.

"We all have the same interest in the long run," he said, sitting in the shade of his garage, surrounded by dozens of antique tractors.

"It makes me happy to see we are getting water to the river," he said, "... We had so many parties, we had so many reunions eating fish by the river. I missed seeing it."

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