Toxic wastewater from copper mine spills into river in northern Mexico

By Matthew Brennan
20 August 2014

Over 10 million gallons of toxic wastewater leached from a copper mine near the town of Cananea in northern Mexico spilled into the nearby Bacanuchi River on August 6. Reports indicate that copper waste tailings containing sulfuric acid and heavy metals leaked for more than a day from a holding tank into the river after heavy storms hit the region.

Residents downstream from the Buenavista del Cobre mine – one of the largest porphyry copper deposits in the world located 25 miles from the US border – began reporting on August 7 that the river had turned bright orange and contained a “rotten smell”. These reports came nearly 24 hours after the spill began. There was no adequate warning from either mine operators or state regulatory officials. On August 10, Mexico’s National Water Commission (NWC) cut off municipal water supplies to seven towns along the river, affecting a population of well over 20,000 people. Local farmers were told not to let their livestock drink the water three days after the spill.

Reports indicate that an orange slick now covers at least 40 miles of the river, which is itself a tributary of the much larger Sonora River. Some of the water supply to the state’s capital Hermosillo, a city of 800,000 people located along the Sonora River, has also been cut off.

The delay in notification by both mine officials and state agencies has been accompanied by reports of widespread fish die-off in the river, as well as cattle deaths. Agriculture is the leading industry in the northwestern state of Sonora, followed by copper, silver and gold mining. Mine officials and the NWC have sent water tanker trucks to temporarily replace the municipal water supply that was cut last week. Already reports are emerging that these trucks are running dry too quickly.

A woman from Arizpe with two children, who was turned away from a water truck after supplies had run out, also voiced concern about food to AFP news services, “If they kill a cow, we don't know if we can eat it... They say if the (cattle) drink just a little water (from the river), they get infected.”

Another farmer told news agency Terra: “The trouble is nobody’s telling us much about the spill. We don’t even have milk because the cows drank the water, and we don’t know what the chemicals have in them. People are panicking, we are being told not to touch any water or to take a bath.”

In addition to the sulfuric acid used for processing extracted copper from the mine, the leached wastewater also contains heavy metals such as arsenic and cadmium, which can cause nausea, vomiting, skin inflation, and various forms of cancer in cases of high-level exposure.

Jaime Salazar Varela, a chemical engineering and metallurgy expert from the University of Sonora, told news agencies: “As far as I know, this is the worst environmental problem that has ever occurred in Sonora…Particularly concerning are the high levels of metals in the river, which are already being independently verified. While acids can be neutralized, the heavy metals are very difficult and expensive to remove. These will have long term effects on the kidneys and livers of people in the area.”

Mexico’s Department of Environmental Protection (PROFEPA) has called for mine operators to lead the cleanup efforts, and to provide the “implementation of a total remediation plan” in the affected areas over the next five years. Mining officials have thus far dumped 100 tons of lime onto the river, in an effort to try to neutralize the acid, and are constructing dams to stem the spill.

PROFEPA’s decision amounts to an absolution of any criminal responsibility of the mine owners, and allows the perpetrators of this potentially deadly negligence to self-report any deleterious environmental damages or legal violations going forward. This is in line with the government’s long-standing cover-up of the crimes of Mexico’s industrial mining giants.

The Buenavista del Cobre copper mine is a subsidiary of Grupo Mexico, the largest mining company in the country and one of the biggest throughout Latin America. It is principally owned by Mexico’s second richest individual, German Larrea ($16 billion).

Grupo Mexico has a sordid history of flouting mine safety regulations, enforcing brutal working conditions, and avoiding any serious consequences after decades of negligence. In 2006 for instance, 65 miners died in a methane gas explosion at the Pasta de Conchos mine in Coahuila, days after miners had openly expressed concern about poor safety conditions.

This past February, five miners died in the San Luis de Potosi coal mine, after the cage they were riding broke and fell 750 meters down a lift shaft. The Mexican Miners’ Union (SNTMMSRM) wrote an open letter accusing the company of flagrantly disregarding years of complaints, and contracting out health regulations enforcement to the lowest bidder.

A US subsidiary of Grupo Mexico, Asarco, paid the United States government $1.79 billion to settle hazardous waste lawsuits across 19 different states as recently as 2009.

Another report from 2009 by a Cananea occupational health and safety (OHS) team concluded that there were over 200 serious health hazards at the Buenavista copper processing facilities, the same facility which housed the holding pond that leaked into the Sonoran River tributary last week.

Thus far, Grupo Mexico (which reported an increase of $509 million in profit in the second quarter of this year alone, a 74 percent increase from the first quarter) officials have responded with open indifference, downplaying the significance of the spill.

Juan Rebolledo, vice president for international relations, told media outlets: “The content of these acids is not toxic in itself…There's no problem, nor any serious consequence for the population, as long as we take adequate precautions and the company pours lime into the river, as it is currently doing."

The company has refused to confirm what chemicals specifically were released into the river. Residents have speculated that cyanide may also have been included, which the company denied on its Facebook page.

Fear of potential cyanide contamination is founded on concrete experience. Just one year ago, in August 2013, a trailer truck containing cyanide for processing in the Sonora’s Canadian-owned Mulatos gold and silver mine overturned and released the poisonous chemical in the Rio Yaqui River, resulting in a mass fish and plant life die-off and another shortage of drinking water.

The spill in Cananea also came days before the Mexican government formally opened up its state-owned oil and electricity sectors to privatization. The minerals industry was also largely state-owned up until 1982. As of 2005, it had been reported that the mines in Mexico average around 50 accidents a year.

There are obvious parallels to Freedom Industries’ chemical spill near Charleston, West Virginia in January of this year. In that eerily similar scenario 300,000 people had their drinking and bathing water cut off for nearly five days, and no criminal charges were brought against mine owners who had placed the lives of potentially millions in jeopardy. The longer term effects of these spills are yet to be determined.

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