A year after a devastating mine spill in Mexico, the United States is facing its own disaster as millions of gallons of mine wastewater were unleashed to a tributary of the Animas River in Colorado.

On Aug. 6, 2014, 11 million gallons of a copper sulfate solution poured out of a containment pond and polluted the Bacanuchi and Sonora rivers, affecting the livelihoods of more than 22,000 Sonorans about 25 miles from the Arizona border.

Contaminated water created by the mining company spraying sulfuric acid over piles of crushed ore was sent to a holding pond that breached, said Ann Maest, chief scientist with E-Tech International, a New-Mexico-based nonprofit that provides environmental technical support to communities in less industrialized countries.

At the Gold King Mine in Colorado, an Environmental Protection Agency crew accidentally triggered a blowout in an inactive mine that released about 3 million gallons of contaminated water created by rain and snowmelt contacting mine walls and wastes, she said.

But both were highly acidic — the Sonora spill more so — and carried high concentrations of toxic metals such as cadmium, copper and zinc, which in high concentrations can be harmful to humans and aquatic life. The predominant metals in both cases were the relatively less toxic aluminum and iron.

After both spills, fear and confusion reigned. People wanted to know if it was safe to drink the water, whether the sediment settled in the river was dangerous, and what the long-term effects would be.


In some ways, life along the Sonora River has returned to normal. Children are back in school, there is running water, fields are cultivated, cattle are being raised. The black or brown water tanks that dotted the landscape are mostly gone, residents say.

But people still don’t drink straight out of the water faucet if they can afford to buy 5-gallon water jugs. In school, children are given purified water. Farmers haven’t gone back to cultivating all their land.

“People were not prepared to sow last fall because they didn’t know if the wells would be reopened,” said Adolfo López, a former mayor of Banámichi who comes from a family of ranchers and farmers.

Before the spill, he said, for each 2½ acres sowed he harvested 6,000 pounds of peanuts and made 65,000 pesos, about $4,000. After the spill, he said, he was able to harvest only about 1,100 pounds of peanuts for each 2½ acres. And last year his family didn’t sow the entire 37 acres.

They weren’t alone. About 70 percent of the land in Banámichi wasn’t sowed last year, he said. People just didn’t know what to expect.

Fields adjacent to the river were soaked with contaminated water as rains from Hurricane Odile caused the river to swell a month after the spill. Wells within 1,600 feet of the river were initially closed.

Farmers and ranchers have received about $17 million for their losses out of a $125 million fund — under the current exchange rate — set up by Grupo México. But López said individuals got little of that.

Leading up to the anniversary of the mine spill, a committee of Mexican federal agencies that oversee water quality and environmental protection reviewed what they’ve done so far:

  • Paid $75 million to residents, farmers ranchers and to remediate the impacted zone;
  • Removed 6,000 cubic meters of contaminated silt up to 19 miles from the spill (the total impacted area is 168 miles);
  • Provided medical care to 360 people, most with skin problems and some with gastrointestinal, eye-related and neurological issues;
  • Created a portal with water test results by area and well, along with reports of where the money has gone.
Skepticism runs high

Many residents don’t believe the government claims.

“We don’t have any kind of certificate that says the area is clean,” said López. “There’s no tranquillity that our future generations will have a good quality of life in the river.”

Poder, a nonprofit that works to improve corporate transparency and accountability in Latin America, is helping about 600 residents and filing public information requests related to the spill and its aftermath. The group also has taken legal action to ensure that mining companies are more respectful of the environment and that the Mexican government raise the nation’s drinking-water standards to be more aligned with those in countries such as the United States. For instance, the level for arsenic is 2½ times higher than what’s allowed in the United States.

The government assured residents they would get water-treatment plants and a specialized medical clinic. Neither has happened, said Julieta Lamberti, a researcher with Poder.

Another firm has filed two class-action lawsuits, and a Cananea attorney is negotiating with the federal government’s committee on behalf of the residents of Bacanuchi, a small town closest to the spill.


Besides establishing the trust, Grupo México was fined $1.4 million. The company was using installations that weren’t finished and did not have the required operating permits, in violation of several federal laws, when the spill happened. Because the project was under construction, there were no overflow ponds or impermeable linings to contain it. A valve that could have stopped the spill hadn’t been installed.

The open-pit copper mine is en route to becoming the second-largest mine in the world in terms of production, Grupo México has said. In 2012, it announced a $4.1 billion investment, to be completed next year, that would increase annual copper production from 200,000 tons to 510,000 tons.

Grupo México and the Mexican government said the trust fund could increase if there was a need. But some residents say the money has only divided people.

“People are angry at each other because somebody got more than them,” said Tom Mattews, owner of Hotel Los Arcos in Banámichi.

He and other U.S. citizens who live along the Rio Sonora founded a nonprofit to push for cleanup at the mine site in Cananea and of the river, he said. The Rio Sonora Foundation, incorporated in Arizona, will work with researchers to do independent monitoring and blood testing. It will have an educational component and will work toward remediation and preventing future spills, said Jesus Romo, a Tucson attorney who also lives in Banámichi part time.

“The river is in extreme danger, but it’s not dead,” Romo said. “We are still in a position to prevent a catastrophe and fix what has been done.”

Heavy metals don’t disappear; they can only be diluted or change form. As acidity levels diminish, metals become solid and if the river is not moving fast, solids can sink and cover the river bottom, Maest said. They could be stirred up during a big storm when flows are much higher.

A point of concern to many is the Molinito reservoir downstream, which provides water to about 800,000 residents of the state’s capital of Hermosillo.

Whether metals that settle in sediment will cause a problem — the biggest unknown in both the Sonora and Animas spill — is a hot scientific question, said James Field, a professor in the department of chemical and environmental engineering at the University of Arizona and a researcher with the Superfund program.

“Some of the key questions are whether organisms that live in the sediments are taking up metals; if so that may be an avenue for metals to get into the food chain,” he said. And what happens if there is a change in water chemistry or acidity?


The Aug. 6 spill was not the first one in the region.

In 1979, a major spill from the same mining area contaminated the San Pedro River and killed aquatic life over a 60-mile stretch north of the border. Water samples showed high concentrations of heavy metals and high acidity.

Richard Kamp, who has studied mining-related water quality threats in Cananea and the watersheds, is working to form a consulting committee that could include a three-year monitoring program for water, sediment and soil in the Sonora River and a small stretch of the San Pedro River. Kamp is the director of E-Tech International.

Maest, who works with Kamp, said the well data she has seen looks fine, but it takes time for water to move from the river to groundwater. A watershed study would investigate other sources of contamination including naturally occurring metals and acid and pollution from activities such as agriculture and sewage disposal to put the mining inputs into perspective and prioritize watershed cleanup.

“That mine has long ways to go,” Kamp said, “and Cananea and the river deserve to be protected.”

Contact reporter Perla Trevizo at 573-4213 or ptrevizo@tucson.com. On Twitter: @Perla_Trevizo