Samarco has said that the volume of tailings released from the dam burst at its Brazilian iron ore mine was significantly lower than initial estimates of more than 50 million cubic metres.
On 5 November, the Fundão dam at the company's Germano mining site near the town of Mariana in Minas Gerais ruptured, reportedly killing 17 people.
Following its 60-day update, Samarco confirmed that the volume of tailings released was around 32 million cubic metres.
Around 85% of the tailings were retained within 85km of the dam.
The company also undertook various activities to stabilise the situation and avoid more material from entering the Rio Doce system.
As part of these measures, Samarco constructed dikes to contain tailings and revegetation along the Gualaxo and Doce rivers.
Furthermore, the company is planning dredging of the Candonga hydroelectric dam in order to improve water quality.
Samarco's team used sonar techniques to study a 670km stretch ranging between the mouth of the Rio Doce and Risoleta Neves hydropower plant.
They detected fish living in areas affected by the turbidity plume and also in unaffected tributaries of the river.
The company is also planning to carry out monitoring studies to determine the identity of species present.