Bighorn Tailwater Trout: Steady Flows, Midges, and Nymphs for Winter Success

Name’s Artificial Lure, checking in from the Big Horn country. We don’t worry about tides out here – the Bighorn’s a tailwater, so Yellowtail Dam is our “moon,” and flows have been steady and very wade‑friendly according to recent USGS flow summaries. Mornings are starting out cold in the teens and low 20s, climbing into the upper 30s and low 40s with light wind and high clouds, pretty classic December tailwater weather per the latest National Weather Service round‑up for south‑central Montana. Sunrise is right around 7:45 a.m., sunset just after 4:30 p.m., giving us a tight but very fishable winter window. Montana Outdoor’s mid‑December trout report says winter fishing has “officially arrived” statewide, with the big tailwaters like the Bighorn still producing good trout despite the chill. Fish activity’s concentrated in the soft stuff: deeper seams, slow walking‑pace runs, and the heads and tails of the big wintering holes. Midday has been best, roughly 11 to 3, when that weak sun finally penetrates and bumps the water temps a degree or two. Recent word from local guides along the river is that most boats are still seeing solid numbers – 20‑plus fish days if you stay on the nymph game – with the mix running heavy to **rainbows** in the 14–18 inch class and plenty of **browns** from 16–20, plus the odd bruiser over 22 inches. Whitefish are thick in the deeper lanes, which is a good sign you’re in the right speed of water. Nymphing is king right now. The best producers have been: - **Small midge patterns** in sizes 18–22: zebra midges (black, red), thread midges, small midge emergers under a yarn or bubble indicator. - **Baetis nymphs** and tiny **pseudos**: olive or brown mayfly nymphs in 18–20 as your top fly. - A **scud or sowbug** in tan, gray, or orange as the anchor; the Bighorn’s grocery store is still full of them. - For spin anglers, small **marabou jigs**, 1/16–1/8 ounce in black, olive, or brown, drifted slow along the bottom. When the clouds stack up and the breeze lays down, there are still sporadic mid‑day midge clusters. Keep a size 20–22 **Griffith’s gnat** or tiny midge cluster handy; the trout won’t go crazy on top, but patient heads‑up fishing can pick off a half‑dozen nice rainbows in the slicks. Streamer fans should think small and slow. A lightly weighted **olive or black Woolly Bugger**, micro sculpin, or thin white baitfish stripped just enough to wiggle has been moving a few bigger browns off the ledges. Forget the hero swings; keep it tight to the bank, low and slow. For bait where it’s legal in the broader Bighorn country (check regs carefully on the main river), nightcrawlers threaded on a small hook and bounced through the slower winter pools, or a pinch of salmon eggs, have been putting pan‑sized trout and whitefish in the bucket on nearby smaller creeks and ponds. A couple local hot spots to circle: - **Afterbay to 3 Mile**: Classic winter drift. Work the inside bends and the softer shelves; the big buckets This content was created in partnership and with the help of Artificial Intelligence AI.