Montana regulators have approved a Canadian company's plans to expand the Golden Sunlight gold mine near Whitehall.
Tuesday's Department of Environmental Quality decision allows Barrick Gold Corp. to expand one pit and open another.
New mining will occur on 68 acres and produce almost 53 million tons of waste rock.
DEQ officials say the expansion will extend the 200-worker mine's life by two years to 2017.
The DEQ permit requires that polluted water from mining be captured and treated.
It also requires Barrick to prepare a plan to use the wall of the new mine pit for bat and raptor habitat. The company also must put a ground movement monitoring system in place to ensure safe access to the pit when operations cease.