The Mariana dam disaster, also known as the Bento Rodrigues or Samarco dam disaster, occurred on 5 November 2015, when the Fundão tailings dam at the Germano iron ore mine of the Samarco Mariana Mining Complex near Mariana, Minas Gerais, Brazil, suffered a catastrophic failure, resulting in flooding that devastated the downstream villages of Bento Rodrigues and Paracatu de Baixo, killing 19 people. The extent of the damage caused by the tailings dam collapse is the largest ever recorded with pollutants spread along 668 kilometres (415 mi) of watercourses.

Mariana is the oldest city in the state of Minas Gerais, Brazil. It is a tourist city, founded on July 16, 1696, and retains the characteristics of a baroque city, with its churches, buildings and museums. It was the first capital of Minas Gerais.