Fishing Report Updated September 5, 2021
This Yellowstone Park fishing report is valid from September 5 until the first serious cold snap, usually around September 20.
The next two weeks will be exceptionally crowded on famous waters near the road (Soda Butte Creek, I’m looking at you) and on waters that host fall-run brown trout. Everybody who says to themselves “I’m going to go fish Yellowstone Park after Labor Day because the summer crowds will be gone” comes between now and the first good cold snap and makes their own crowd. The roads won’t be quite as busy, but the roadside fisheries will be just as busy or busier than they were in July. To shed the crowds somewhat, fish first or last light AND/OR hike into rough-water fisheries like the Yellowstone in its Black and Grand Canyons.
Most small streams are too low now, and geothermal fisheries like the Firehole and Lower Gibbon will run too warm with this week’s heat. Stick to the bigger, rougher waters without much geyser influence until it cools off some.
The Yellowstone River is best in its Black and Grand Canyons, especially away from the roads where crowds haven’t been fishing (and won’t be). Hopper-dropper rigs are the main draw, but if they aren’t eating these, throw streamers. Look for Tan Drake and BWO hatches around midday.
The Gardner River is still a bit warm downstream of Boiling River but is fishing well upstream. Hopper-dropper rigs are good here too, but Euro-nymphing with a heavy stonefly and a medium-sized attractor nymph will produce a whole lot more fish. Wade closer rather than casting farther! The brook trout water upstream from Osprey Falls is basically done for the year.
The Lamar River, Soda Butte Creek, and Slough Creek will be crowded most days they are clear. You are probably better off fishing late in the day than first thing in the morning. Crowds will be lower at either end of the day than they will be 10:30 to 4:00. Absent a hatch, nymph with slender mayfly nymphs and midge pupae (a black and copper Zebra Midge is money). This tactic will draw some fish before they really get active. Hatches may include BWO, Flavs (#14-16 Green Drakes), Tan Drakes, midges, and maybe a handful of large (#10) full-size Green Drakes. Small hoppers, ants, and beetles can also work. Soda Butte, lower Slough, and the roadside sections of the Lamar may be horrifically crowded during the middle part of the day, especially when the buffalo prevent accessing one of the three areas and push everybody into the other two.
The Firehole River and Gibbon River are still not good choices. The Firehole is still too warm and may very well have low fish numbers after a long and brutal summer. The lower Gibbon is likewise going to be a touch too warm for another two weeks. If you want to fish the Gibbon, stick to the water above Norris Geyser Basin. Hoppers should be out.
The Madison River in YNP is generally too warm, but the shallow riffles downstream of 9-Mile Bridge allow cool night air to mix with the river. This in turn means the fall-run browns are starting to nose into the area near the West Entrance. This fishing will be best first thing in the morning. Swing streamers and big soft hackles for bragging rights, though most fish are caught on a large stonefly nymph trailing some sort of egg or attractor nymph.