The Boulder River

Depending on water levels, our floats on the Boulder often begin near the Natural Bridge State Monument — a dramatic geological formation where the river disappears underground before re-emerging downstream. This stretch is excellent for dynamic angling, balancing dry fly opportunities with aggressive streamer fishing through deep canyon pools and boulder-strewn runs.

Anglers can utilize larger streamers in the river's many deep holes and along the undercut banks to entice predatory fish. Alternatively, switching to nimble dry fly presentations allows you to target the Boulder's robust Brown Trout population. During dry fly season, the clarity and structure offer numerous opportunities for sight fishing to rising fish — something the Boulder delivers with unusual consistency.

The Boulder's relatively low fishing pressure makes it an excellent option throughout the summer. Unlike the more well-known Yellowstone or Bighorn, the Boulder sees a fraction of the angling traffic — many days, you won't encounter another boat on the water. Later in the season, the river flows through ranch country with wide riffles and long banks — prime hopper fishing from late July through August.

Species & What to Expect

The Boulder supports Rainbow, Brown, and Brook Trout. Browns dominate the lower river and tend to be larger, favoring the deeper pools and structure where they can ambush prey. Rainbows are found throughout, particularly in the faster riffles and pocket water of the upper canyon sections. Brook Trout appear in the tributary creeks and upper headwaters.

Fish on the Boulder average 12 to 16 inches, with browns over 18 inches taken regularly on streamers and hoppers. The river's gradient and structure create a fast-paced fishing experience — you're constantly moving through new water, reading new seams, and adjusting presentations. Guides often describe the Boulder as the most "fun" river in the rotation because of the constant action and variety.

Access & Location

The Boulder River is one of our closest waters, located just minutes from the lodge in the Boulder River Valley south of Big Timber. The short drive means more time on the water and an easy, relaxed pace to the day. It's an ideal option for the first or last day of a package, or any day when you want to maximize fishing time without a long shuttle.