Grupo Mexico spent much of August and September responding to issues created by an August 6 spill of 40,000 m3 of acidic copper sulfate solution from its Buenavista del Cobre mine into the Bacanuchi River in Sonora state, Mexico. The Bacanuchi is a tributary to the Sonora River, which was also contaminated.
Grupo Mexico established a $151 million trust fund to pay for cleanup and was working to overcome the impact of the spill on communities in the affected areas. However, the company continued to be beset by negative media coverage and contentious statements from government officials.
On September 22, Grupo Mexico responded to news reports of a second spill, saying, "There was no second discharge of acid copper sulfate solution from any of the dams of Buenavista del Cobre. As a consequence of hurricane Odil, Tinajas 1 and Tinajas 2 dams filled up with rainwater, a situation that was timely notified on September 18 to the corresponding authorities. Mexican Environmental Protection Agency (PROFEPA) informed that discharge derived from the rainwater contained some ferrous substances but was below levels considered a risk to human health.
"On September 20, water measurements conducted by PROFEPA, the National Water Commission, and the company reported normal acidity levels in the Bacanuchi and Sonora rivers."
The Buenavista mine produced 115,800 mt of copper in concentrates and 66,400 mt of copper cathode in 2013. Grupo Mexico in currently investing $3.7 billion in a project to expand the mine's production capacity by 175%.