Photo: Toxic spill in Mexico (@betoeliasm)
A toxic spill at a copper mine operated by a Grupo Mexico unit in the northwestern state of Sonora is the Mexican mining sector’s worst environmental disaster in recent history, the government said.
The mine operated by Buenavista del Cobre spilled a total of 40,000 cubic meters of copper sulfate acid into the Tinajas stream in the town of Cananea on Aug. 6.
“This incident at the mine, based on what some specialists in the area have told us, could be considered the worst environmental disaster in the country’s mining industry in modern times,” Environment and Natural Resources Secretary Juan Jose Guerra Abud said at a press conference on Tuesday.
A report by the National Water Commission, or Conagua, found that the spill was caused by a flawed polyethylene pipe at one of the mine’s leachate tanks and a faulty valve at another tank and placed the blame for the disaster squarely on the company.
But Buenavista del Cobre, the Grupo Mexico unit, says studies show the spill was caused by an unforeseeable increase in rainfall, which triggered a rise in the level of water and copper sulfate at a holding tank under construction at the copper mine.
“That’s absolutely false,” Guerra Abud said, adding that reports from the national weather service indicate that no such heavy rains occurred.
During the presentation of a report on the incident, he said the spill contaminated the 17.6-kilometer-long (11-mile-long) Tinajas stream and the Bacanuchi (64 kilometers) and Sonora (190 kilometers) rivers, as well as the 15.4-million-cubic-meter El Molinito reservoir.
The contaminants found in those waters include copper, arsenic, aluminum, cadmium, chromium, iron, manganese and lead.
On Aug. 18, the Profepa environmental protection agency filed a criminal complaint against Buenavista del Cobre and another Grupo Mexico unit, Minera Mexico, for their alleged role in the spill.
That complaint could lead to a fine of more than 40 million pesos (roughly $3 million) being imposed on Grupo Mexico, the world’s fourth-largest copper producer.
The Environment and Natural Resources Secretariat’s priority is “to apply, within the bounds of the law, the maximum allowable penalties and primarily to guarantee the environmental remediation of the site,” Guerra Abud said.
It is the company’s obligation to carry out that clean-up effort, he said, adding that the government will take the legal action necessary to ensure that work is completed.