The Gallatin River is pretty blown out now. It will be even worse after the next 2 hot days. You might get lucky if you chuck a streamer or nymph rig tight to pockets along the bank or in the slowest moving water you can find. I would wait until the river drops again.
Gallatin River Webcam – Located at Karst, which is about 1/2 way between Bozeman and Big Sky on HWY 191.