Vale SA’s decomissioned Xingu dam is at “imminent risk of collapsing,” according to a statement on Wednesday by the Regional Labor Department for the southeastern Brazilian state of Minas Gerais.

The Xingu tailings, or mining waste, dam in the town of Mariana, already devastated by a 2015 dam rupture which killed 19 people, had its risk level elevated last October by Brazil’s National Mining Agency. Although the Xingu dam stopped receiving mining waste in 1998, Vale still employs workers there to monitor its stability ahead of a planned decommissioning procedure.