Toxic Spill in Sonora The tip of the iceberg

by Sinai Guevara

September 15, 2014

On August 8th, millions of gallons ofcopper sulphate, sulphuric acid and heavy metals were spilled from a Grupo Mexico mine into the Sonora river located at Sonora state, Mexico. It is being calledthe worst ecological disaster in Mexican history.

Also, for the first time in Mexico’s history, the The Environmental Protection Agency (PROFEPA) has been forced to file a legal complaint against the mining company making them completely responsible for the discharged toxins.

The scandal and the evident lack of resources available to alleviate this disaster, has forced the federal government to announce the creation of a trust, by which Grupo Mexico will pay 2 thousand million MXN, (151,630,000 USD) to repair the environmental damages. This trust is aside from the trivial fines and penalties (3 million USD), that have been taxed to the company until now.

Thousands of people affected

The families affected dont have water supplied directly to their houses, and depend upon water from wells which may become contaminated by the spill. Due to this, the pollution threatens at least 22 thousand people living in the seven surrounding municipalities: Aconchi, Arizpe, Banamichi, Bavicora, Hermosillo, San Felipe and Ures.

It is important to have information about the quality of well water and other drinking water supplies in the affected area. Exposure to toxic heavy metals in the long term can cause damage to a number of organs including the liver, the lungs, and the renal and reproductive systems and have been linked with hepatitis, cancer and osteoporosis. Some toxic metals may affect the neurological system, and have been associated with diseases such as Alzheimers and Parkinsons, It is, therefore, important to prevent exposures to these metals via drinking water supplies.

Greenpeace does water sampling


Greenpeace went to Sonora on the last week of August, near the zone affected by the spill in Cananea, to document the situation over the affected area and also to carry out sampling on different areas of the Bacanuchi River. We were attempting to gatherdata onthe quality of drinking waterand the quantities of heavy metals present in the water. The results of this study will be given to the media in mid-October.

Also, on the day of the accident, people living in that zone took a water sample and sentthem to a laboratory. The results showed that the toxic metals arsenic, cadmium copper and chromium were all present at concentrations above World Health Organisation advisory limits for drinking water. The concentration of aluminium was also reported to be extremely high.

It is necessary to carry out survey work to try and fully understand the actual and potential future impacts of the spill in order to carry out effective remediation work on contaminated sediments and river banks.

However, this spill is not just affecting the communities that are near the river. It is also affecting the rights of others, like the Yaqui tribe that have being fighting for years to avoid the restriction of water use for agricultural activities in exchange for the water to reach the urban areas of Hermosillo through the Independence aqueduct, which was suspended by the Supreme Court. This mandate could be disobeyed because the Sonora River that fed the Molinito dam, which carried the water to the Hermosillo city was polluted.

Only a few days after this toxic spill in Sonora, a ProyectoMagistrals mine triggered another spill on the town of El Oro, in Durango, polluting 2 thousand cubic meters of water with cyanide, which is potentially lethal.

The tip of the iceberg

The population is now supplied by bottled water.

The population is now supplied by bottled water.

The message that the government is giving to the citizens, and to future investors, is that Mexico it is still a paradise for people to pollute.

The Sonora spill is just the tip of the iceberg on the pollution of Mexican rivers.

According to the Nacional Committee of Water, near 70% of the Mexican rivers present some type of contamination, but nothing is being done to reverse it, and much less to prevent it.

Over the last two decades, companieshave been operatingin a country with a very lax vigilance and verification that has had terrible consequences. The promise of new jobs and economic improvementshas been offset bythe costlydegradation of ecosystems. With the new Environmental Responsibility Law, which came into effect on July 7th, 2013, damages are only analyzedafter they occur. It’s pay or damage repair without taking into accountthe full cost.

Mining is one of the most polluting industries

The method of miningminerals and the waste and damage it generatesmake the mining industry one of the most polluting industries, but not the only one. We should not take out of our sight that the recent structural reforms in Mexico openedthe door to the consolidation ofan extractive model of natural resources, which is ignoring the environmental justice for the communities and ecosystems. Economic profits are prioritized over human rights.

Greenpeace joins to the demands of the affected communities in Sonora. We demandthat the commitment of the Grupo Mexico company, the state and federal government, is fully met so a true remediation exists, which should include:

  • Full recognition by Grupo Mexico company of the social and environmental effects of the spill on the 7 municipalities around the spill zone.
  • Complete drainage of the Sonora and Bacanuchi rivers, so the water of rivers and wells could be used again for irrigation and human consumption as well as for the environmental balance.
  • Reparation of the environmental, health and socio-economic damages caused by this contaminant leak; even if some consequences appear years later, as may be the case of health issues.
  • Transparent and public access to the information derived from the sampling and of the agreed measures and actions taken by the company and government.
  • A public mid and long term contingency plan for environmental and health issues.
  • The immediate and permanent closure of the Buenavista mine.
  • Inspection to the other facilities of Grupo Mexico, in order to avoid future accidents in other country regions.

The main sources of water pollution

  • Municipalwater
  • Leaching from landfills
  • Water coming from productive activities, mainly industrial, agricultural and mining activities.
  • Toxic industries: Some of the substances discharged by the industrial activity in the rivers and lakes of the planet are highly toxic and have direct effects on living organisms and human health. In most instances, safer alternativesexist.

Seeking solutions

At Greenpeace we advocate caution as the only way to prevent such unfortunate accidents like this recent spill in Sonora.

Having precautionary laws as the proposal made by the citizenry Water for All Water for Life, would prevent the affected populations of being ignored.

SinceFebruary 8th, 2012 , more than 460 researchers and members of social organizations from 28 states have participated in the preparation of this citizens’ initiative , which has as main objectives:

  • Water for everyone, ecosystems and food sovereignty
  • End to pollution, overfishing and destruction of watersheds and aquifers
  • End vulnerability to floods and droughts

Viewand sign the proposal here

The urgent need to act now


Cattle drinking water of the Bacanuchi River, polluted by the spill.

According to the National Water Commission, 70% of national rivers have some degree of contamination, but little is being done to reverse it, much less to prevent it.

– Sina Guevara

Greenpeace Mexico

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