Montana’s Boulder River is a hidden, fly fishing gem of the upper Yellowstone Drainage. Small, fast, and aptly named, the Boulder is hard to beat. The river’s out of the way location, combined with its proximity to other major, better known, rivers, tend to keep fishing pressure in the moderate range. Like the Stillwater, movies such as The Horse Whisper and A River Runs Through It chose areas on this river to film their breathtaking scenes.
Our floats on the Boulder, depending on water levels, start below the Natural Bridge State Monument a stretch excellent for dry fly fisherman and streamer fisherman alike. Using large streamers in the many deep holes and along the undercut banks is a wonderful way to catch the rivers large brown trout. For the dry fly angler, the Boulder River has excellent caddisfly hatches throughout the summer. Just use a large hopper, floating it right along the banks, picking up brown trout and rainbow trout as you go. A person on a Montana fly fishing trip in July should always have lots and lots of hoppers.
During the summer, due to the relatively low fishing pressure, standard dry flies like the Parachute Adams and Elk Hair Caddis work very well. Of course, as the Boulder River flows through ranch country with lots of hay fields, it is also prime hopper fishing water come late July through August.
Golden Stones - early July can boast some excellent dry fly and nymphing for good size trout. Mayflies - July has excellent numbers of PMDs. Caddis - July and early August have our annual summer Caddis. Caddis, Elk Hair Caddis, and small Pheasant tail droppers are most effective. Terrestrials - Hoppers and beetles are excellent options as the August heat sets in.