Below Ennis Lake the Madison drops through Bear Trap Canyon and then flattens out for the last thirty miles to Three Forks. It is a different river from the Upper: shallower, weedier, warmer, and closer to Bozeman. That combination makes it the most accessible reach and the one most often shut down by summer heat.
Lower Madison — Today's Report
Thursday, August 13, 2026
Live Data
Updated Aug 13, 7:05 AM MDT
Lower Madison Fishing Report
Ennis Dam to Three Forks
Water Temp (McAllister)69.3°F
Flow Rate (McAllister)1,220 CFS
Water ClarityGood
I'm going to be straight with you: skip the Lower today. The gauge below Ennis Dam read 69.6 degrees at five o'clock this morning. That's the overnight low, at the coolest hour of the day, and it's already knocking on 70. By early afternoon this water will be pushing into the mid 70s, and a trout hooked and fought at those temperatures has a real chance of dying no matter how gently you handle it. FWP has the standard hoot owl in place, closed 2 pm to midnight, but the legal window and the responsible window are two different things down here in August, and this week the responsible window is razor thin. The mechanics are the same every summer. Ennis Lake is a big shallow pan that soaks up sun all day and sends that heat straight downstream. The 1230 cfs coming out of the dam right now is decent volume, and clarity is actually good, but the river is shallow and wide below Bear Trap Canyon and it gains temperature fast once the sun is up. The weed growth is doing what it always does in August, growing like crazy, and you'll deal with drifting salad on most casts by mid morning. To be fair, this river fished very well earlier this summer. The brown drake and caddis fishing in late June and into July was legitimately phenomenal in the evenings, and the fish came out of it healthy. But those days are done for now. The fish are currently stressed and podded up in the deepest, coolest water they can find, the springs, the deeper slots up in Bear Trap, the mouths of the few cold trickles that come in. You can find them there and catch them, and I'd ask you not to. Pounding heat-stressed trout stacked in a thermal refuge is a bad look and worse biology. So when does it come back? September. The first run of cold nights knocks Ennis Lake down, the water drops back through the 60s, and the Lower turns back into one of the better fall fisheries in the area. Baetis show up on the cloudy days, the crayfish bite turns on hard, and streamer fishing through Bear Trap in October is some of my favorite fishing of the whole year. The canyon stretch also empties out once hunting season starts, and the access from Warm Springs down through Black's Ford gives you miles of water to yourself. That's worth waiting for. In the meantime, the answer is forty minutes up the road. The Upper Madison came out of the dam at 58.5 degrees this morning and is fishing well on an early start, and that's where every one of my trips is going this week. If you're set on something different, the reservoirs are an option too, with gulpers eating Callibaetis on Hebgen in the mornings. There's plenty of good fishing around right now. It just isn't here, and forcing it on this reach today does real damage to a fishery we all want healthy in September.
Tactics for today
If you absolutely must fish it, and I'd rather you didn't this week, make it a first light mission and be off the water by 9 or 10 am. Don't push to the legal 2 pm cutoff just because you can. Fish 2X or 3X tippet so fights stay short, keep every fish in the water, and forget the hero shots. Your best dawn play is a crayfish pattern dead drifted along the bottom through the deeper buckets, fished on a stout leader with enough weight to stay down. Hopper along the grass banks in the first hour can move a fish or two as well. One legitimate alternative down here that doesn't stress trout at all: the carp cruising the shallow flats toward Three Forks. They pull hard, they don't care about warm water, and stalking them with a crayfish fly on a six weight is a genuinely fun way to salvage an August day on the Lower.
Recommended Patterns
Lil Kim (copper) #4-8Clouser Crayfish #6-8Pheasant Tail #14-16BH Ascending Caddis (green) #16Morrish Hopper (tan) #10
The water
Water leaves Ennis Lake off the top, which means it arrives warm. That single fact drives most of what happens on this reach: early hatches in spring, excellent fishing in the shoulder seasons, and hoot owl restrictions through much of the summer.
Bear Trap Canyon, immediately below the dam, is BLM wilderness: a nine-mile walk-in canyon with pocket water and real whitewater. It holds up better in the heat than the valley water below it.
Downstream of the canyon the river spreads out shallow and weedy over a gravel bed. It fishes more like a big spring creek than a freestone, and the trout see a lot of flies.
Access
Bear Trap Canyon (BLM): Wilderness. The developed trailhead sits at the downstream end of the canyon, off Highway 84; the trail follows the bank about nine miles upstream toward the dam. No vehicles, and the whitewater has drowned experienced boaters. Wade it.
Warm Springs: Top of the valley float water, and the busiest launch on the reach.
Damselfly: Next launch below Warm Springs, above Black's Ford. Common short-float take-out.
Black's Ford: Mid-reach access with a ramp.
Cobblestone: Walk-in fishing access site with parking. No boat ramp.
Greycliff: Lower access toward the Three Forks end.
Readings come from USGS gauge 06041000 near McAllister, below Ennis Dam. Water temperature matters more than flow on this reach. Once it holds above 70°F, fishing is hard on the trout no matter what the flow looks like.
Frequently, from mid-July into August. When water temperatures stay high, Montana FWP closes fishing daily from 2 p.m. to midnight. The current report above shows today's water temperature; check FWP for the official restriction list.
When is the Mother's Day caddis hatch on the Lower Madison?
Usually the first two weeks of May, before runoff. It is the best-known hatch on this reach and can produce excellent dry fly fishing for a short window.
Can you fish Bear Trap Canyon?
Yes. It is BLM wilderness below Ennis Dam, reached on foot from the trailhead at the downstream end of the canyon off Highway 84. It holds cooler water than the valley section below it, which makes it a better bet in hot weather.
How warm is too warm on the Lower Madison?
Once water holds above about 70°F, hooked trout struggle to recover. That threshold is what triggers hoot owl restrictions, and it is worth respecting even on days when no restriction is in force.
