The Gallatin has been one of the best nearby fishing options. Expect a good amount of ice and slush floating down the river with the recent cold weather. To best avoid these tricky conditions head up into the canyon. Don't worry about getting out early, fishing will heat up with the water temperatures. Nymphing is the most productive method for the Winter season. Try different stonefly patterns in natural colors like coffee and black. Smaller golden stones are also a good option. For a dropper fly I have liked a flashback #16 Hare's Ear, a #14-16 gold lightning bug, and a small zebra midge in black.
The Gallatin River is one of the more scenic, blue-ribbon trout waters found in the Bozeman area. The river changes in character from a small mountain stream near its headwaters in Yellowstone National Park to a medium-sized, classic western river once it flows into the Gallatin Valley. The middle portion of the river flows through the Gallatin Canyon and is characterized by pocket water and swift currents. Once it leaves the canyon stretch, the river slows its pace with much of the trout water being found in a classic riffle, pool, and run water types. The Gallatin River is noted for having very clean, cold water throughout its course and served as the setting in which much of "A River Runs Through It" was filmed.