Bighorn River Fall Fishing Roundup: Nymphs, Smallies, and Grizzly Bears

Good morning from Big Horn, Montana—this is Artificial Lure with your September 17th fishing report brought to you by the banks of the mighty Bighorn River. Fall’s rolled into the valley: cool mornings in the low 50s, highs expected near 73, and a light dusting of fog on the water at sunrise, which hit at 6:51 a.m. tonight’s sunset’s lined up for 7:23 p.m. Let’s talk river first—flows are steady after last week’s rains pushed just enough water to liven things up, but streams themselves are still running low. According to the September 14th Bighorn River update on Montana Outdoor Radio Show, nymphs are the ticket right now; those set on dry flies are working hard for every take. The big browns and rainbows are feeding deep, with patterns like San Juan Worms, Zebra Midges, and Pheasant Tails getting solid action. Fish are still biting, but you’ll want to get your fly down and move slow. Anglers floating from Afterbay to 3 Mile have been reporting between 12 and 20 fish per rod—mostly healthy rainbows but a fair mix of browns, averaging 14-17 inches, with a few slabs over 20 in the net. Spin anglers have found success on smaller Rapalas and soft plastics, especially those with a hint of orange or gold. The bite is best early and slowing by late morning, so don’t sleep in—get rods in by first light. If you fancy hunting warmwater fish, local reservoirs like Yellowtail and Bighorn Lake are producing steady smallmouth with the usual tubes and Ned rigs, and perch are hitting well off the weed edges. Pike activity is just starting to ramp up as waters cool, especially near drop-offs and submerged timber. Pablo Reservoir’s also noted for perch if you’re looking to fill a bucket. Nightcrawlers or three-inch paddletails in white or chartreuse are local favorites. For the fly guys chasing something different, the upper creeks are still holding brookies and the odd cutthroat, though you’ll have to hike for them as levels are low. Smaller hoppers and bead-head nymphs are your best bet in skinny water. Lake Mary Ronan is turning on for perch, and Kokanee salmon are starting to show signs of spawn—try casting Cowbell rigs, Wedding Rings, or a little glow hook below a dodger in 30–40 feet of water. As for tidal activity: no coastal tides here, so you can set your watch by the river flows. Hot spots this week? The Afterbay stretch continues to be a crowd-pleaser for numbers, but the faster riffles just above the 3 Mile Access are turning up the biggest fish. If you want more solitude, make the run up to Bighorn Lake’s southern bays for smallmouth and the occasional walleye. For bait, stick with the classics: nightcrawlers, leeches, and for artificial, lean into black or olive streamers, or a gold Panther Martin spinner if you’re casting hardware. Word from Zimmer Tackle is Mack Days are getting hotter—the big fish are on the move, so don’t be afraid to go deep or try something wild for trigger bites. Don’t forget to watch for wildlife, and as always, pac This content was created in partnership and with the help of Artificial Intelligence AI.