Prosecutors in the Brazilian state of Minas Gerais found that 18 tailings dams at mines run by Vale require some work to guarantee their safety following heavy rains in recent months.

In a statement, state prosecutors said an analysis of 31 dams had revealed the need for the preventative measures, although they stressed there was no direct damage to the highest risk structures.

“Based on the data provided, 18 dams were found to present issues that must be resolved to avoid problems with the functioning of the structures,” prosecutors said, adding that all the 18 dams were run by Vale.

Reuters reported that prosecutors said Vale would have 10 days to present a report informing what action it would take.

Vale, in response to a request for comment, said it was conducting detailed evaluations of its dams to make necessary improvements, particularly looking at the issue of access which had been impacted by the rains.

In February 2021 Vale reached a $6.89 billion settlement with authorities in the state of Minas Gerais over the 2019 tailings failure at its mine in the town of Brumadinho in Minas Gerais. That dam failure resulted in the death of at least 259 people. Vale and BHP own the Samarco Mine where a dam collapse in 2015 left 19 people dead.