On Sunday, the leak continued in a gypsum waste water pond at the mine site.
A company spokesman told Yle that it is expected that a safety dam will be completed during the day. Leakage outside the mining area was stopped late on Sunday.
Operations continued to fully plug the breach in the gypsum waste water pond, even though most of the water had been drained by Sunday afternoon.
Around 200 people were involved in the effort, including soldiers from the Kainuu Brigade and local volunteer fire fighters.