A new report estimates that the socio-environmental damage from the 2015 tailings dam failure at the Samarco Mine in Brazil is about $6.7 billion (37.6 billion reais).

Reuters reported that the study was conducted by consultancy Lactec at the request of Brazilian federal prosecutors to measure the costs of the disaster.

The report comes as Brazilian authorities, Samarco and Samarco co-owners BHP Group and Vale SA enter the final phases of a re-negotiation of a 2016 settlement related to the disaster.

The dam collapse near the town of Mariana killed 19 people and severely polluted the Rio Doce river, compromising the waterway all the way to its outlet in the Atlantic Ocean.

“We did an environmental valuation and we're giving a base to prosecutors so they have a reference point with which to make future decisions,” said Renata Cristine da Silva Gonçalves, a researcher at Lactec.

“We don't have any way to define what prosecutors will do with the results of the study,” she added.

Samarco told Reuters it would comment on the matter as soon as possible.