Yellowstone National Park Fishing Report - September 11, 2025
Here's this week's Yellowstone National Park Fishing Report.
The big news out of Yellowstone this week is the full re-opening of the Firehole, Madison, and Gibbon Rivers for the Fall season. Hoot Owl Angling Restrictions have been lifted.
Firehole River
We are excited to have this gem of a river open again for the fall season, and the upcoming forecast looks good to see some fall hatches of baetis mayflies and rising trout. On sunnier afternoons consider reaching back into that terrestrial box and drifting small ants and hoppers along grassy, undercut banks.
Madison River (in YNP)
The Madison in the Park has been fishing well since it reopened, and we’re starting to see the first migratory fish of the season trickle upstream from Hebgen Lake. With cooler, wetter weather in the forecast this week, we anticipate a few more lake-run fish making their way into the system.
While this isn’t yet the full push of fish we’ll see by late September or October, it’s a promising start—and these early arrivals are often more aggressive and more responsive to Trout Spey tactics or a well-presented streamer. If you’re eager to get a jump on the fall migration, now’s a great time to start exploring.
Northeast Corner – Slough, Soda Butte & Lamar
Keep a close eye on flows up in the Cutthroat Corner this week You can check on the Lamar Flows HERE. If the forecast holds true we may see enough rain to muddy the Lamar and possibly Soda Butte. If they remain clear expect to see sparse hatches of Heptagenia, Hecuba, and Baetis mayflies all bringing fish to the surface in the afternoons. Slough should remain fishable, and will be a good option to find fish rising to hatches of Hecuba and Baetis mayflies.
Yellowstone River – Caldera Stretch
September can be a terrific month to find technical dry fly targets on this section of the Yellowstone River. The fish that remain in the system this time of year are often large, and wise. So, don't go without your A-Game. Long casts, long leaders, and good drifts are required to fool these feeding fish. This will remain a spinner game (size #12-18 in rusty) in the mornings, but be prepared to find fish feeding on emerging mayflies (size # 16-18 in olive), often just below the surface.
Gallatin River
The Park stretch of the Gallatin River will benefit from some overcast afternoons in the form of mayfly hatches and rising trout. As has been increasingly the case on the Gallatin this September, the fish you are looking for are formidable opponents by this late stage in the season. They have seen all forms of trout stream foolishness, and will respond only to perfect drifts presented from a stealthy approach. If you're up for the challenge, these can be some of the best fish of the season. If trophy hunting isn't your thing there is still a healthy population of trout in the Park stretch eager to reward a well presented nymph under a dry fly.
