(Photo: A canal diverts water from the Sao Francisco River, shown in 2010. Credit: Water Alternatives, Flickr Creative Commons)The collapse of a dam in Brazil that killed at least 84 people — with hundreds still missing — is sending contaminated water toward a large river that provides drinking water to communities in several states. The dam storing iron ore waste from Brazilian mining company Vale SA was breached on Friday.
Muddy water containing high concentrations of iron oxide has already affected the Parapoeba River, which flows into the larger Sao Francisco River. The Sao Francisco provides drinking water and water for irrigation to five of Brazil’s 26 states.
Authorities and companies involved in river water management are focusing on the Retiro Baixo hydroelectric dam, where they hope the contaminated water can be contained and cleaned before it is released toward the Sao Francisco, CBS News reports.
In the meantime, the Geological Survey of Brazil is monitoring the velocity of the mine waste, and estimates it will reach the dam between February 5 and February 10.
The Retiro Baixo hydroelectric plant has closed water intakes to “preserve its equipment,” but tests have been carried out and the dam is safe, says dam owner Eletrobras subsidiary Furnas. The company is in contact with authorities to evaluate mud displacement and to take necessary measures. The dam was inspected by the National Electric Energy Agency in 2018, writes CNBC.
Vale, the world’s biggest producer of iron ore, says it will reduce its annual output by about 10% in order to decommission dams that, like the Brunadinho dam, were built by the “upstream method.” Vale estimates that investments of around R$ 5 billion will be necessary to decommission its upstream dams and estimates that the decommissioning process will occur over the next 3 years.
In 2015, a dam at another mine partially owned by Vale (jointly with BHP Billiton) ruptured, killing 19 people and sending toxic mining waste into the Rio Doce, which eventually reached the Atlantic Ocean. At the time, that breach was called the “worst environmental catastrophe” in the country’s history (via Al Jazeera). Efforts are still underway to clean up the environmental damage from that failure.
Rivers affected by mining tailings like iron ore and other heavy metals can end up contaminated for decades, according Joao Paulo Machado Torres, a professor of Environmental Biophysics at the Federal University of Rio de Janeiro.
