I'm not quite as childish as a liberal, but if the land/river ratio is there.....
Here you go.

Which river? The Gallatin River, Yellowstone River, and Boulder River in Montana were used for filming, but not the actual Blackfoot River.

This is a canyon that the Gallatin River runs through. Would this do? Does Yellowstone National Park offer what you are thinking of?
Blackfoot river, Montanna
