**TITLE:** Dam Collapse in Mariana
On the afternoon of November 5, 2015, a quiet subdistrict in the interior of Minas Gerais was swallowed by a wave of mud that no one managed to predict in time to contain. The Fundão dam, controlled by the mining company Samarco, ruptured and released 62 million cubic meters of mining tailings over the valley below, destroying entire communities, contaminating one of Brazil’s most important rivers, and marking one of the country’s worst environmental crises in history.
The disaster occurred in the subdistrict of Bento Rodrigues, 35 kilometers from the center of the municipality of Mariana, in Minas Gerais. The Fundão dam was part of the Germano Mine, located in the district of Santa Rita Durão, and was controlled by Samarco Mineração S.A.—a joint venture between two of the world’s largest mining companies: Brazil’s Vale S.A. and the Anglo-Australian BHP Billiton. The structure had been built to store tailings from iron ore extraction in the region and was undergoing a heightening process at the time, as the reservoir had already reached its maximum capacity.
Around 3:30 p.m. that afternoon, a team of outsourced workers was sent to the site after an initial leak in the containment was detected. They were attempting to drain part of the reservoir to relieve pressure when, about fifty minutes later, at 4:20 p.m., the dam suffered a definitive rupture. A massive wave of tailings sludge surged into the Santarém creek valley, flooding everything in its path with devastating speed and volume. The subdistricts of Bento Rodrigues and Paracatu de Baixo, both in the mudflow’s path, were almost completely destroyed. Other villages and districts along the Gualaxo River valley were also affected.
Bento Rodrigues was completely cut off by land after the disaster. Access to the area depended on unpaved rural roads that were overtaken by mud, making it impossible for firefighters and rescue teams to reach the site by ground. Search and rescue efforts could only be carried out with helicopter support, significantly delaying operations during the most critical hours. The situation was worsened by the fact that neither the mining company nor the neighboring communities had contingency plans or defined escape routes for residents in case of a rupture. There was a school in the affected area, but teachers managed to evacuate the students in time before the building was reached by the flood.
By 6:30 p.m. that same day, the tailings had reached the Doce River. The impact on the river was immediate and severe. The Doce River basin drains an area of approximately 86,715 square kilometers, with 86% in Minas Gerais and the remainder in Espírito Santo. In total, 230 municipalities depend directly or indirectly on the waters of this river. The arrival of the mining sludge disrupted the water supply for entire cities along its course. On November 9, the city of Governador Valadares suspended water intake from the Doce River. The following day, the municipality declared a State of Public Calamity due to water shortages. On November 13, the Brazilian Army set up a free water distribution point in the city center, supplied by Samarco.
The wave of mud continued its course toward the sea. On November 16, it reached the municipality of Baixo Guandu, in the northwest of Espírito Santo, leading the local government to suspend water supply from the Doce River. The tailings traveled hundreds of kilometers until they reached the river’s mouth and mixed with ocean waters, contaminating the marine environment with a load of debris whose effects, according to experts, would take at least a hundred years to fully dissipate.
The damage to the Doce River’s biodiversity was deemed catastrophic. The Brazilian Institute of the Environment and Renewable Natural Resources (Ibama) reported that, of the 80 fish species in the river, 11 were already threatened with extinction before the disaster, and 12 were endemic to that basin, found exclusively there. After the disaster, concerns about the definitive extinction of these endemic species grew significantly, especially due to the immediate fish kill and habitat destruction. The long-term effects on species that use the estuary at some stage of their life cycle and on marine fish near the river’s mouth remained uncertain for years.
Samarco initially reported that two dams had ruptured: Fundão and Santarém. On November 16, the company corrected the information: only the Fundão dam had failed. The tailings from Fundão had overflowed the Santarém dam without breaching it, creating confusion in the initial communications about the accident’s extent. The total volume of 62 million cubic meters released made the event the world’s largest disaster involving tailings dams and the biggest environmental impact in Brazil’s industrial history.
Investigations into the disaster’s responsibilities unfolded into complex legal proceedings in the following years, involving Samarco and its parent companies. The repair of infrastructure damage in the municipality of Mariana was estimated by the city government at around 100 million reais. Communities like Bento Rodrigues had to be completely relocated. The Doce River, which for centuries had sustained thousands of fishing and farming families along its banks, remained for years as a symbol of a mineral extraction model that, in that November of 2015, cruelly revealed its environmental and human cost.