 Montana Power Company originally built the dam, PPL Corporation purchased it in 1997 and sold it to NorthWestern Corporation in 2014.Since the dam's construction in the Missouri River gorge, it has flooded a fair portion of the Great Falls - the cascades between Grand Fall and Crooked Falls, which lies several miles upstream - and reduced the flow over Great Falls to such an extent that much of the bedrock is visible.The dam was constructed on top of a cascade that Lewis and Clark observed to lie just upstream of Grand Fall.