HELENA, Mont. (AP) – An oil and gas company faces criminal charges for a 2011 oil spill prosecutors say polluted a stream in northwestern Montana.

A federal grand jury indictment unsealed Tuesday charges FX Drilling Co. and field supervisor Quay Geza Torok with negligent discharge of oil into waters of the United States and failure to immediately notify federal authorities of the spill.

Prosecutors say Torok discovered a 3-inch line connecting two oil wells had broken on an oil field located on the Blackfeet Indian Reservation on June 12, 2011. They say the spilled oil and production fluid, estimated at up to 840 gallons, made its way to Cut Bank Creek nearly a mile away.

Attorneys representing the company and Torok said Wednesday there is no evidence the spill reached the stream.