The Blackfoot River is well-known to local anglers and floaters. It’s a lovely undammed river noted for its variety of fish habitats and its 30 miles of “recreation corridor,” [1] which allow easy public access to the river. Read Norman Maclean’s classic, A River Runs Through It, to get a feel for the place.
Links:
[1] http://www.moon.com/destinations/montana/missoula-and-northwestern-montana/the-swan-and-blackfoot-valleys/blackfoot-valley/recreation