Click here for interactive Gallatin river map From Montana Fish, Wildlife and Parks
The Gallatin River itself is just about twelve miles long from its origin at the confluence of the West and East Gallatin rivers to Three Forks, Montana, where it joins the Jefferson and Madison rivers to form the Missouri River.
Perhaps more noteworthy as trout waters through much of the year are the West Gallatin and East Gallatin Rivers.
The West Gallatin begins in Yellowstone National Park and runs right along Highway 191 for almost all of its length. Its clear, pristine waters beckon fly fishermen all along the route with hatches that include salmonflies, caddis and a variety of mayflies.
The East Gallatin flows through agricultural land in the Gallatin Valley and holds some beautiful brown trout that wait under overhanging brush and undercut banks. Unlike the West Gallatin, which is more of a crystal-clear mountain river, the East Gallatin is often a bit turbid and offers great fishing during grasshopper time and is a good water for trying minnow-imitating nymphs.
The Gallatin River below the confluence of its forks suffers from sedimentation and warm water temperatures, dewatering, and the presence of M. cerebralis, the causative agent of whirling disease. Trout populations decline in the lower river due to these factors and a variety of other cumulative impacts.
