Warm River

About Warm River

Warm River is a spring-fed tributary of the Henrys Fork, located near Ashton, Idaho. Its name comes from the consistent, moderate water temperature year-round, a result of its origins from Warm River Spring. This spring emerges on the flank of the Yellowstone Caldera, providing a stable flow that makes the river fishable when other waters might be high or frozen. The Warm River itself is a smaller stream, best fished by wading. It flows into the Henrys Fork where the Mesa Falls road crosses. The lower section of the Warm River is stocked with Rainbow Trout near the campground. Hiking upstream from here, or venturing into the deeper canyon, will put you into wild populations of Rainbow, Brown, and Brook Trout. Mountain Whitefish are also present. The consistent water temperature supports insect hatches throughout much of the year, making it a prime spot for dry fly fishing. You’ll need to pay close attention to the prevalent insect life and approach carefully. The banks can be steep in places, especially as you move into the canyon, so be mindful of your footing. The Warm River offers opportunities for Rainbow, Brown, and Brook Trout, with some of these fish growing to respectable sizes. Mountain Whitefish are also a common catch. Insect hatches occur consistently, providing food for the trout. Look for Caddis and Stoneflies, as well as smaller mayflies like Baetis. When the dry fly bite is on, try patterns like Elk Hair Caddis, Parachute Adams, or small Stimulators. If the fish are holding deeper, a nymph fished under an indicator or tight-lined can be very effective. Consider Bitch Creek Nymphs, Hare's Ears, or Prince Nymphs. Streamers can work well, especially early or late in the day, for larger trout. Try Woolly Buggers or Sculpin patterns. When working the water, focus on riffles, pools, and seams along the banks, especially where there's any kind of structure like undercut banks or submerged rocks. The stocked Rainbow Trout will often be found in the faster water near the campground. The wild trout upstream will be more selective and require a stealthier approach. Be prepared to wade and cover a lot of water. Anglers often share this river, so be courteous and give other fly fishers space. Keep your casts tight and your drifts clean.