In the Mexican state of Sonora, a mining company recently discharged sulfuric acid into the Sonora River and its tributaries. The occurrence prompted the government to prohibit thousands of local residents from drinking from the rivers.
Additionally, the company responsible for the mining operation, Grupo Mexico, is accused of waiting too long before notifying the authorities about the incident. They apparently also lied about the spill’s causes.
Spill and Cover
On Thursday, August 7, some40 thousand cubic meters of sulfuric acidspilled from the copper mine Buenavista del Cobre (located in in Cananea) into local rivers. According to the company Operadora de Minas e Instalaciones Mineras, S.A. de C.V., owned by Grupo Mexico, massive rains caused one of the mine’s dams to overflow. However, Government inspectors concluded that one of the mine’s pipelines that transports the acid broke.
The acid then infiltrated the Bacanuchi River and eventually spread to the Sonora River, which is 261 miles (420 kilometers) long and carries around 171 million cubic meters per year. The inhabitants of the Arizpe municipality, some 31 miles downriver from the spill, observed “an unusual red shade” in the river and commented on its rare smell.
In addition to initially denying responsibility for the spill, the company is also accused of waiting 24 hours to notify authorities. Cesar Lagarda, a regional director of Mexico’s National Water Commission (CONAGUA), has declared that “the responsibility is 100% of the company […] they did not promptly report what happened and that qualifies them for severe sanctions; we are already imposing fines.”
CONAGUA has confirmed that the Sonora River now possesses high levels of contaminants. A week after the incident, the acid and minerals that polluted the water can be found some124 miles downriver. One article reports that there are now 1.78 milligrams of aluminum per liter, far over the maximum limit of 0.02 milligrams. When the spill wasfinally reported, local authorities ordered regional citizens not to touch the Sonora River, Bacanuchi River, and some of their tributaries’ waters.
Water service was suspended in several areas
Water service was suspended in seven municipalities, including Arizpe, Cananea, Banamichi, Baviacora, Aconchi and Ures. Water in Hermosillo, the state capital, was apparently partially suspended even though only 3% of the city’s water supply originates from the Sonora River. Government agencies provided water bottles to citizens affected by the suspension.
According to data from Mexico’s National Institute of Statistics and Geography and a 2010 census, Sonora has a population of 2.6 million citizens. Hermosillo comprises around 784 thousand people, while Cananea, the municipality most impacted by the acid spill, has more than 30,000 inhabitants.
Moreover, the spill’s timing is problematic. The Mexican daily “Milenio” explains that the region is emerging from a decade-long drought, and heavy rainfall means that the Sonora River and its tributaries are overflowing. Add acid and metals into these rivers, and it is not surprising that the local environment suffers.
Sonora – U.S. Trade Affected?
Besides the local population, local non-mining related industries, such as milk producers, were also affected. Additionally, and perhaps more worrisome, the state’s meat sector will be adversely influenced, as cattle ranchers are concerned about their animals drinking from the rivers. This is particularly problematic since cattle from Sonora is exported to the United States. If there is a real possibility that the animals have drunk contaminated water loaded with aluminum, they may have to be put down. This would translate into significant financial losses for Mexican cattle growers and would adversely impact U.S.-Sonora commerce.
In fact, just this past June, Sonoran cattle growers reported that Sonora is the Mexican state which exports the most cattle to the U.S. – over 300,000 heads of cattle were exported during the 2013-2014 period.
A Fitting Punishment?
If the Mexican government can be trusted, Grupo Mexico will face heavy fines and be subject to monitoring in order to ensure that it continues working to mitigate the pollution’s impact on the local environment. The company will have to test the rivers’ surface waters every 15 days for five years as well as the subterranean waterways.
Whether the company actually complies with these standards remains to be seen. Additionally, CONAGUA has announced that Grupo Mexico will be fined 1.2 million Mexican pesos (some $92,000 USD) for the incident. The company may also be fined by the Federal Prosecutor.
Mexico’s Secretariat of Economy highlights the importance of Sonora’s mining industry, as it is a major producer of copper. The state also produces 28% of Mexico’s gold, among other minerals. In other words, the recent acid spill will not persuade local authorities to ban mining projects in the state. We can only hope that Mexican authorities have learned from this new incident and will be more aggressive in monitoring mining companies in Sonora.