Boulder River Fishing Report
This Boulder River fishing report is valid from October 5 through October 15, 2025.
The Boulder is very low, but it has come up slightly. Fish the lower river in the afternoons. Above Natural Bridge will be ice water.
- Hatches: BWO.
- Dry Flies: BWO imitations, maybe small hoppers on the warmest days.
- Nymphs & Wets: Various BWO-sized mayflies (see the report for the Yellowstone), medium-sized Girdle Bugs and other stoneflies.
- Streamers: Woolly Buggers, Sparkle Minnows, small jig-nymph streamers.
Learn more about fishing the Boulder.
Learn more about our float trips, including on the Boulder.
Boulder River Streamflow Data
This stream gauge is near Big Timber, right at the bottom of the Boulder near its confluence with the Yellowstone. The Boulder actually runs slightly higher near the Boulder Forks Fishing Access, since a great deal of water is pulled off for irrigation downstream. Further upstream, the Boulder is much smaller, since the East and West Boulder both come in near Boulder Forks.
Flows under 300cfs are fishable on foot, 300-500 on foot or floating in an ultralight raft, 500-1500 both on foot and floating, and 1500 to 2500 only floating.
Boulder River streamflow data.
Boulder River Fishing Report – Relevant Links
Note: We update our general fishing report far more often than our fishery-specific reports like this one, especially between November and April.
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