Aside from being a very good fishery, the Gallatin River was the river seen in almost all of the fishing scenes in the great movie "A River Runs Through It". As a fly fisherman, you need to be aware that this is primarily a river for wading and has good access through most of its length. In the summer months you need to know that the river sections close to Big Sky are full of recreational "white water" floaters. On average, the fish (rainbows, browns and cutthroat) are not large. If you are looking for the larger fish, you will need to fish the lower sections closer to Three Forks.
Gallatin - by Gallatin River Guides
Gallatin River - by bigskyfishing,com
GALLATIN RIVER FISHING GUIDE - by Montana Anglers
Gallatin River Fly Fishing - by Montana Fishing Outfitters