Sonora ranchers: Mine's 'unethical' water pumping leaving them dry

CANANEA, Sonora — In her eight decades on a remote ranch on the outskirts of Cananea, Maria del Socorro Hernandez Cuen, 84, said her well has never gone dry, until this year.

Outside the rugged home where she’s lived since age 2 — where the Sonora River used to flow, sprinkled with fish and crawdads — the trees are dying, their shriveled fruits falling from the branches, victims of an ongoing drought.

But it’s only been since March, when mining giant Grupo Mexico started transporting truckloads of water pumped from the Sonora River basin to its copper mine in Cananea, that she began having to rely on neighbors to bring her bottled water for drinking, cooking and cleaning.

“I’ve never seen it dry,” she said of her well, speaking in Spanish. “So many years here, and they (friends) tell me now I’ll have to sell. I’m not going to sell. I’m going to keep fighting.”

On a neighboring property, ranch hand Alfredo Yanez del Río said the water level in his well is at least eight feet below normal, so low that the pump isn’t strong enough to bring water to the surface.

Twenty miles south along the same river, in the town of Bacoachi, Ernesto Acuña fielded calls day and night from neighbors angry that they don’t have water.

In his nine years as manager of the two wells that serve Bacoachi’s 2,000 residents, he’s never been so stressed, Acuña said, sitting at his kitchen table in late July. Children have stayed home from school due to the scarcity of water, he said. He’s been shutting down the wells’ pumps at night, in the hopes the wells will recharge overnight so homes have water in the morning.

“It’s a lot of pressure for me,” he said in Spanish. “Until now, we’d never had problems.”

While droughts have come and gone over the years, residents here say unrelenting groundwater pumping to fuel Grupo Mexico’s Buenavista del Cobre copper mine in Cananea is a major factor in the declining water table, threatening the mostly small-scale ranching communities along the Sonora River and their children’s futures.

The volume of the mine’s water use became highly visible this spring, as dozens of water trucks, at times 60 trucks per hour, began traversing the scenic highway known as the “Ruta Río Sonora,” which tracks the Sonora River and the historic communities along it.

Each water truck carried 30,000 liters of water from new wells further south on Sonora River, destined for the mine in Cananea.

Locals say they felt the hit to their water supply almost immediately, particularly in Bacoachi, so they took action.

“We all saw it happening,” said Pedro Vejar, 36, a Bacoachi rancher and garlic farmer. “The trucks were working almost all day, from 4 in the morning to 12 at night. … That’s why the whole town made the decision to stop the trucks.”

Forming the “Committee in Defense of Water,” residents hailing from Sonora River towns as far south as Arizpe have mounted an ongoing road blockade, manned 24 hours a day, to prevent the water trucks from reaching the mine.

For more than two months they’ve maintained the blockade, allowing all traffic to pass except for the water trucks, despite exhaustion, intimidation from state police and from the powerful mining company itself, they say.

Grupo Mexico has fired workers for speaking out against the mine in the past, said Eduardo Ríos, local rancher, environmentalist and protester.

“We’re fighting a monster in Grupo Mexico,” he said.

Grupo Mexico: No ‘improper’ water use

Grupo Mexico, which owns Tucson-based Asarco, has agreed to halt the use of water trucks “until we have new official information on the state of the aquifers,” the company said in a statement to the Star.

“The health of the watersheds and the availability of water for consumption, the activities of the people of the communities and for the needs of the company are a priority for Grupo México,” according to the statement, written in Spanish. “We absolutely deny that there is improper use of water by the company or that it is contrary to the care of the resource in the region.”

Grupo Mexico also said nationwide, mining uses 1% of the country’s water, through pumping permits known as concessions, granted by Mexico’s water commission, Conagua.

But that national figure doesn’t reflect the situation in this part of northern Sonora. Here, the mine’s concessions account for 57% of water pumped from the aquifers, according to a 2023 report from Mexico’s environmental ministry, Semarnat.

Protesters accuse the federal water commission, as well as the Sonora governor’s office, of putting the mine’s interests over the rights of the people, pointing to Mexican law that says water allocations must prioritize human consumption.

“The water law is very clear: It’s first for human use,” Vejar said in Spanish. “If there’s a surplus, it’s for ranching and farming. In the case of more surplus, it’s for industry. Here, they’re giving the priority to the industry.”

Mining defines historic town

A mile above sea level, Cananea is the starting point for both the San Pedro River, which flows north into Arizona, and the Sonora River, which flows south. Tributaries including the Bacanuchi and Bacoachi rivers make up the Sonora River basin.

Mining has defined this town since the late 18th century, and looms large in the background of daily life here, said Cananea native Humberto de Hoyos, whose father worked as chief engineer for the mine before Grupo Mexico acquired it.

An elevated view of the open-pit copper mine, its blue-green concentration pools or its tailings ponds are visible from most neighborhoods in the hilly town.

Production has increased since Grupo Mexico bought the mine in 1990, and Buenavista del Cobre is now the third-largest copper mine in the world, Grupo Mexico says.

“Grupo Mexico every year comes out and says, ‘Our production went up a certain percent, we’re building more,’” said de Hoyos, who is one of the organizers of the highway blockade. “But they never figured out where they were going to get the water from, and now they’re having problems.”

Grupo Mexico also pumps groundwater from the San Pedro Basin, just northeast of Cananea, where long-time residents have been saying for years their wells are going dry, de Hoyos said.

Decades ago many families on the ejido lands above the San Pedro leased their water rights to the mining company, some for as little as 30,000 pesos per year, less than $2,000, de Hoyos said. Some are now trying to get out of those contracts, as their wells go dry, but the mine is putting up legal roadblocks to ending the agreements, he said.

Locals say the San Pedro Basin is in trouble. Data from Mexico’s water commission, Conagua, show there’s a deficit of 6.7 million cubic meters of water in the San Pedro basin, a figure that water advocates say is an underestimate.

And since 2005, Grupo Mexico’s water concession has allowed it to pump 19.5 million cubic meters annually from the same aquifer, nearly three times the volume of the water deficit.

Combined with an ongoing drought and scant natural recharge to the San Pedro aquifer, residents in northern Sonora are warning Arizonans that their declining water table will affect Upper San Pedro Basin north of the border, too.

Water experts in Arizona and Sonora say more research is needed to better understand how groundwater pumping on the San Pedro in Mexico impacts the same aquifer in Arizona.

“I imagine in Sierra Vista, they’re going to understand soon,” Vejar said.

Back on the Sonora River, wells that have served communities for 100 years are drying up, and natural ponds, known as ojos de agua, that survived previous droughts have disappeared.

Hydrologist Agustin Robles Morua of the Sonora Institute of Technology, in Obregón, said locals are witnessing first-hand what is borne out by recent research that he took part in along the Bacoachi and Bacanuchi Rivers, two tributaries of the Sonora River.

“These people live on the river, they are seeing the impacts themselves. They can see the trees dying, they can see the water levels are no longer what they used to be,” he said. “They have a lot of empirical knowledge gathered over many years of living in the region and knowing when something is wrong.”

To Robles Morua, the citizen protesters are “heroes” facing off against a powerful company that’s also one of the few sources of employment in the area, outside ranching.

“They are the only ones that are really fighting for the sustainable use of the most important resource in the region, which is water,” he said. “In my opinion all of these environmental activists are heroes. They’re fighting against the government agencies, they’re going against a private company that has all of the resources in the world.”

And a future without access to groundwater isn’t hard for them to imagine, he said.

“They already have evidence of what happened in San Pedro River,” he said. “They don’t want same to happen on Sonora (River) side.”

Grupo Mexico moves wells

In a statement to the Star, Conagua’s Northwestern Basin director Jesus Antonio Cruz Varela said the Buenavista mine’s water extraction from the Bacoachi River hasn’t increased since 2015. Conagua has implemented remote measurement at water sources to ensure that extractions don’t exceed the volumes of water granted, the statement said.

Activists point out that the mine’s concession from the Bacoachi aquifer — 16.7 million cubic meters of water per year, pumped from 46 wells — exceeds Conagua’s own estimate that the Bacoachi has an availability of 4 million cubic meters of groundwater.

In 2021, Grupo Mexico got Conagua’s permission to relocate some of its wells further south on the Sonora River, near Bacoachi, intending to transport the water via a planned aqueduct. After the aqueduct was rejected by the federal government, Grupo Mexico acknowledged water availability problems in a February 2024 report to investors, mentioning an alternate plan that likely referred to the water trucks.

“In the second half of 2023, we experienced a reduction of fresh water in our Buenavista operation as a consequence of a lack of permits that we expect to receive for building a pipeline,” the report said. “For 2024, the company has decided to transport water through other means to secure the needed supply, which will allow Buenavista to operate at full capacity.”

In moving its wells southward, researchers say Grupo Mexico is following the water.

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“There is the intention of the company to move their wells from the northern part, where the aquifer is already depleted, to the southern part where water still exists,” hydrologist Dr. Adrián Pedrozo Acuña said a July interview with Mexican journalist Ana Francisca Vega about the water controversy.

Users are allowed to move their concessions, as long as they stay within the same aquifer, Pedrozo Acuña told Vega.

That is legal, he said, but that doesn’t mean it’s ethical.

Under Mexican law, in times of severe drought, the government is supposed to impose mandatory reductions in industrial water use, but that hasn’t happened, said Bacoachi resident Fernando Ramirez, who also organized the highway blockade.

Restrictions were proposed at a June 19 meeting of a council that weighs in on decisions about the basin, but it was rejected by citizen members who demanded a halt to the mine’s groundwater pumping from the new wells further south on the Sonora River, not just a reduction, said Katy Treviño, Conagua’s technical director.

Water availability disputed

Pedrozo, head of the Mexican Institute of Water Technology, led a recent study that concluded the aquifers beneath two of the Sonora River’s tributaries, the Bacoachi and Bacanuchi rivers, have declined since they were last measured 20 years ago. The study, released this year, was done in collaboration with Mexico’s environmental ministry, Semarnat, the parent agency over Conagua, and the Sonora Institute of Technology.

Researchers, including Robles Morua, recorded drops in groundwater levels of between 5 meters and 25 meters, with the steepest declines at the northern end of the Sonora River basin, closest to the mine, according to the report, which was based on groundwater-level measurements combined with satellite data from NASA’s water-storage observation program, GRACE.

The report warned that Grupo Mexico’s “current strategy of drilling wells in the southern part of the aquifer and transporting water through aqueducts to the north for use is not sustainable, if extraction volumes are maintained. This issue is of critical importance in an aquifer whose historical evolution shows significant declines. Continuing with this strategy increases the potential risk for communities to access water resources and accelerates the overexploitation of aquifers.”

In contrast, last year Conagua updated the status of the Bacoachi aquifer — one of the aquifers that makes up the Sonora River basin — from having a deficit of more than 3 million cubic meters in 2020, to an availability of 4 million cubic meters in 2023.

That determination of water availability green-lights the agency to grant more pumping concessions from the Bacoachi aquifer, de Hoyos said.

“We find that very strange, because these last five years have been the worst drought in the last century,” de Hoyos said. “So how can we have more water when we have such a drought?”

Cruz Varela, of Conagua, questioned the validity of Semarnat study’s methods. Conagua’s assessments are calculated from allowable pumping volumes and climatology data, and informed by raw data from multiple past studies, in accordance with federal standards, the agency said.

In response to the disagreement between the two federal agencies, Conagua and Semarnat, Sonora Gov. Alfonso Durazo has said a new study should be undertaken.

Protesters accuse Conagua, as well as the state government, of favoring the mine by dismissing the results of Semarnat’s study. They cite Mexican president Andrés Manuel López Obrador, who in 2022 announced that a Conagua official had improperly granted water concessions to Grupo Mexico and then went to work for the mining company.

López Obrador, who campaigned on tackling government corruption, told reporters at the time, “We have not yet finished cleaning, purifying public life, because this perverse practice was well-rooted.”

In written comments to the Star, Durazo’s office said in Spanish that the state government supports the ranching and farming communities, and maintains “constant communication and coordination” with federal authorities responsible for ensuring legality and proper documentation of environmental projects in Sonora, “prioritizing the care of natural resources, flora and fauna of the region.”

The statement also described an ongoing “Sonora Water Plan,” that aims to “guarantee water supply for the next 30 years and provide a solution, once and for all, to the problem that has been increasing, without remedial actions, throughout past state administrations.”

‘Water defenders’ continue blockade

Standing in the shade of a large tree at the highway blockade, dozens of ranchers, farmers and their families, many wearing reflective safety vests, mingle under a large blue shade structure in late July. They wave as vehicles pass, honking their horns in support.

A rancher grills chicken over a fire, as others heat up corn tortillas and distribute tacos de tinga, filled with shredded chicken in garlic-tomato sauce, a squeeze of lime and a spoonful of salsa.

Standing near a hand-drawn banner that reads, “Water is not sold, it is cared for and defended,” rancher Norberto Espinoza, who traveled north from Arizpe, says in his 62 years he’s experienced severe droughts, but there was always surface water in certain mountain springs and ponds where his cattle watered.

They’re all dry now, he said.

There’s a strong sense of solidarity here, said Vejar, the Bacoachi rancher who’s been helping to man the blockade for weeks.

“We’re fighting for a just cause. We’re farmers, we’re ranchers, above all, we’re residents. We’re all affected by the looting of water by Grupo Mexico,” he said in Spanish. “The (Sonora River) basin is very small. These aquifers are not capable of industrial exploitation.”

Too frail to join the highway blockade in person, 84-year-old Hernandez Cuen said she sends coffee and snacks to support the protesters.

Since the blockade began two months ago, and the mine’s nearby pumping stopped, Bacoachi’s wells have recovered significantly, Acuña said.

Many activists at the blockade also say their lives were changed by contamination from the Buenavista del Cobre mine’s devastating toxic spill almost exactly 10 years ago, on Aug. 6, 2014.

People who were affected, and human rights advocates, maintain Grupo Mexico has skirted its obligations to account for the extensive environmental damage and health effects stemming from the spill that contaminated the Bacanuchi River, and subsequently the Sonora River that it feeds into.

At the roadblock, Arizpe farmer Jose Luis Espinoza Montoya, 60, lifted up his right pant leg to reveal scarred and irritated skin that he says resulted from dipping his legs into contaminated river water before he heard about the toxic spill. It took Grupo Mexico 25 hours after discovering the spill to notify authorities. Family members who cultivate garlic in fields near the river had their toenails turn black and fall off, he said.

Espinoza Montoya still has bone pain and blood tests he shared with the Star show heavy metals in his system. He received less than $1,500 in compensation from Grupo Mexico, he said.

“They left us abandoned,” he said.

The blockade has held up in the face of intimidation from law enforcement, organizers say — except for one day when dozens of police officers, and a state government representative, arrived and forced a small group of protesters to let five water trucks pass.

Espinoza said the government official told protesters, “These trucks are passing one way or another, sí o sí.“

Soon after, more than 100 additional protesters arrived to fortify the blockade, he said.

Durazo’s office said the police presence was to ensure the safety of the protesters, not to support the mining company.

‘Can’t compete with the mine’

With water access increasingly threatened, some ranchers in northern Sonora are implementing sustainability principles and water-retention strategies, with support from an initiative of Sky Island Alliance, a Tucson nonprofit focused on conservation in the Sky Island mountain ranges of the U.S. and Mexico.

That includes installing rainwater-harvesting systems, and techniques to support balanced flora and fauna on ranchers’ land that can help retain moisture in the soil.

After a late July rain, Eduardo Ríos opened the lid to his 5,000-liter rainwater-harvesting tank to find it full to the brim. Three tubes from various roofs nearby direct excess rainwater to this tank, collecting rainwater for his garden — filled with chiles, tomato and zucchini plants — and dozens of fruit trees scattered across his family’s cattle ranch on ejido land in rural Cananea.

Ríos splashed his hand into the cool, clear water a few times.

“Pure water from the sky,” he said in Spanish.

Figs, peaches, quince and pears trees are among the ranch’s fruit trees. Slender acorn trees are rising from a shaded arroyo that passes by his fields.

Those young trees survived thanks to a suggestion from Sky Island Alliance, which has been working with Ríos for the past four years. The nonprofit advised fencing off the arroyo to keep cattle out and protect the budding trees, which would otherwise be trampled or eaten.

Ríos has carefully tracked water levels in the creek bed behind his ranch for eight years, using a device dug into the center of the creek, a tributary of the Sonora River.

The previously stable water level, about 75 centimeters below the creek bed, dropped to a depth of 100 centimeters once the mine began pumping further south on the Sonora River, he said.

Regular ranchers can’t afford to dig wells anywhere near as deep as Grupo Mexico’s, he said.

“We can’t compete with the mine,” he said.

Vejar, back at the highway blockade, says the mine’s water use is an existential threat. Bacoachi was founded in the 17th century by indigenous communities, including the Yaqui, Ópata and Pima, who farmed along the Sonora River, Vejar said.

“If this water extraction continues, they’re going to erase us, these pueblos much older than the mining industry,” he said.

He’s worried about the future for his 16-year-old daughter and two sons, ages 9 and 4.

“A pueblo without water isn’t worth anything, nor my house, nor my lands,” Vejar said. “So we have to do what we can and fight until the last, because that’s all we have.”