Civil protection authorities in Mexico have alerted the public to a toxic spill into the Bacanuchi river in the northern state of Sonora, from a copper mine run by a subsidiary of mining firm Grupo México, Buenavista del Cobre.
State officials warned people not to use water from the Bacanuchi river after it was observed that a 60km stretch of the river had turned an orange colour, due to a chemical used to dissolve copper from ore.
Following the reports of a new spillage, Grupo México said that heavy rains during Hurricane Odile caused two reservoirs at the mine to fill with water, prompting them to activate pumping teams to contain the situation.
The company has claimed that it has contained the spill.
A previous chemical discharge on 6 August contaminated the water supplies of at least 24,000 people in seven towns when around ten million gallons (40,000m³) of copper sulfate and heavy metals were released into the river.
After denying the accusations, the company has agreed to set-up a $150m trust to pay damages caused by the earlier spill and to fund a major clean-up operation.
According to the government, Grupo México's rights to use the mine will be temporarily or permanently suspended.
The Buenavista copper mine has an annual production of more than 200,000t.