Could get very costly as the pollution cloud from the disaster...

Could get very costly as the pollution cloud from the disaster enters the major river system of the state of Espirito Santo (Pop 3.8m) - the Rio Doce (Sweet River).  The sweet river is perhaps not as sweet as it used to be.

Just read this on Samarco website.

QUOTE
Samarco is paying attention to any impact on Espírito Santo and is in constant contact with the competent authorities regarding to the accident in the dams of Fundão and Santarém, in Minas Gerais. The expansion of the smudge that advances in Rio Doce is being constantly monitored by the company. Samarco is taking all necessary measures to mitigate the generated environmental impacts and, if necessary, to help municipalities and communities in possible occurrences. The collection of water samples in the affected areas has already started and will continue until normalization of the situation. It is important to mention that the company is, at this moment, concentrating its efforts in assisting the people affected.
ENDQUOTE

From Wiki
The Doce River (literally the "sweet river"; Rio Doce in Portuguese) is a river in southeast Brazil, which has an extension of 853 km. It is formed by the junction of the Piranga and the Carmo^[1] near the historical city of Ouro Preto, whose sources are located in the foothills of the Mantiqueira and Espinhaço mountain chains at altitudes of about 1,200 m. It flows in a northeastern direction via Ipatinga, makes a wide curve near Governador Valadares, and flows in a southeastern direction passing through Conselheiro Pena, to enter the Atlantic Ocean near Linhares in Espírito Santo state. Its main tributaries are the Piracicaba, Casca, Matipó, Caratinga-Cuieté, Manhuaçu, Santo Antônio and Suaçuí Grande, in Minas Gerais; the Pancas, Guandu, and São José, in Espírito Santo.

The economy of the basin is based on the following activities:

1. agriculture: dairy and beef cattle, pig raising, coffee, sugar cane, fruits and vegetables and cocoa;
2. industry: siderurgy, metallurgy, mechanical, chemical, food, alcohol, textile, leather, paper and paper pulp; and
3. mining: iron, gold, bauxite, manganese, and precious stones.