Madison River Ennis to Three Forks Hatch Chart

Southwest Montana. Below Ennis Lake dam the Madison transforms — it emerges as a wide, braided, powerful river that cuts through Bear Trap Canyon before spreading into broad gravel flats on its way to Three Forks, where it joins the Jefferson and Gallatin to form the Missouri River.

The lower Madison is defined by its brown trout, including some of the largest in Montana. Rainbows are present throughout but browns dominate, particularly in the canyon and the lower braids. The Bear Trap Canyon section is wilderness — walk-in only, physically demanding, and rewarding. The water from the canyon mouth to Three Forks is more accessible with multiple public fishing access sites.

This stretch is famous for its fall brown trout run, when large fish move up from Ennis Lake to spawn. September and October can produce exceptional streamer and dry-fly fishing for trophy-class browns. Summer hatches are solid but less celebrated than the upper valley — the river is wide and fast, and fish are spread out.

Check current Montana FWP regulations before you go. The Bear Trap Canyon is a BLM Wilderness Study Area — review access rules before planning a wade trip into the canyon.

Shop by type: dry flies, nymphs, Euro nymphs, hoppers and terrestrials, streamers.

Year at a glance

Month	Primary hatches	Also carry	Typical sizes
Jan	Midges	Streamers for post-spawn browns	18-22
Feb	Midges, BWO	Small stonefly nymphs, streamers	16-22
Mar	BWO, midges	Streamers, stonefly nymphs	16-22
Apr	BWO, March Brown	Early caddis, streamers	12-18
May	Caddis, BWO	Stonefly nymphs, runoff likely	Caddis 14-16, BWO 16-20
Jun	Caddis, PMD, golden stone	Salmonfly possible in canyon	PMD 16-18, stones 6-10
Jul	PMD, caddis, yellow sally	Hoppers start, tricos on flat water	14-18
Aug	Hoppers, caddis, tricos	Ants, beetles, late PMD	Hopper 8-12, trico 20-22
Sep	Hoppers, BWO, mahogany dun	Streamers — brown trout run begins	10-18, BWO 18-20
Oct	BWO, mahogany dun, streamers	October caddis, midges	BWO 18-22, caddis 8-12
Nov	Midges, BWO	Streamers for post-spawn fish	18-22
Dec	Midges	Small nymphs, streamers	18-22

January

Cold water and post-spawn fish recovering in deep holding water. Midge fishing can produce on calm afternoons. Streamer fishing for resident fish is worth trying in the canyon and the deeper braids below.

Midges - 18-22. Zebra midge or small Euro nymph in a two-fly rig through slow tailouts.
Streamers — dark and heavy in slow, deep runs.

February

Olives begin on overcast afternoons. Midge clustering in back eddies can bring fish to the surface on warmer days. The lower braids near Three Forks are often more accessible and fishable than the canyon in winter.

Midges and BWO on gray days.
Pheasant tail nymphs subsurface.
Streamers in deeper slots.

March

BWO pick up on cloudy afternoons. The river begins to show some life. Streamer fishing can be productive as water temperatures slowly rise and browns become more active ahead of the runoff season.

BWO - 16-20. Dry and Barr's Baetis emerger.
Streamers — olive and black swung through runs and braids.
Small dark stonefly nymphs along the bottom.

April

March Browns and olives provide dry-fly opportunities on gray days. Caddis begin late in the month. Runoff typically starts building toward the end of April — fish while you can before flows push.

BWO and March Brown, 12-18.
Early dark caddis at dusk.
Streamers in off-color water as flows build.

May

Caddis can be excellent in early May. The river typically blows out mid-month with snowmelt runoff. The lower braids near Three Forks clear faster than the canyon — check stream gauges before making the trip.

Caddis - 14-16. Elk hair caddis and the caddis assortment early in the month.
Stonefly nymphs 6-10 from nymphs.
BWO on overcast days when flows allow.

June

As runoff clears — usually mid-to-late June — the lower Madison comes into form. Caddis and PMDs provide the primary dry-fly action. Some salmonfly activity in the Bear Trap Canyon, though less concentrated than the upper valley. The lower braids fish well for nymphing when flows are still elevated.

Caddis - 14-16. Elk hair caddis in the evenings.
PMD - 16-18. Pale Morning Dun mornings with a pheasant tail dropper.
Golden stone - 6-10 in the canyon and faster runs. A salmonfly dry if adults are on the water.
Yellow sally - 14-16 in riffled sections.

July

Solid summer fishing throughout. PMDs taper off mid-month as hoppers take over. Tricos on the flatter lower braids near Three Forks in the morning. The canyon is worth the hike for solitude and aggressive fish.

PMD - 16-18. Pale Morning Dun with a pheasant tail dropper.
Early hoppers along grass banks — hoppers and terrestrials.
Trico - 20-22. Morning spinner falls on flat water near Three Forks.
Caddis evenings. Elk hair.

August

Hopper fishing is good but the lower Madison's character — wide, fast, and braided — means hoppers work best tight to grassy banks and in the slower side channels rather than the main current. Trico spinner falls in the morning near Three Forks. Fish early; the canyon can be brutally hot by afternoon.

Hoppers - 8-12. Focus on slower edges, side channels, and bank structure. Shop hoppers and terrestrials. Hopper-dropper with a small nymph.
Trico - 20-22 on the lower flats near Three Forks.
Ants and beetles in foam lines.
Evening caddis.

September

The lower Madison's signature month. As water cools, large brown trout begin moving up from Ennis Lake into the river to stage for the spawn. These fish — often 18–24 inches or better — are aggressive and respond to streamers, large dries, and well-placed nymphs. Hoppers hold through mid-September. Mahogany duns and BWO provide afternoon dry-fly action. This is when the lower Madison earns its trophy-river reputation.

Hoppers and ants through mid-September.
Mahogany dun - 14-16 on cloudy afternoons.
BWO - parachute BWO and Baetis emerger, 18-20.
Streamers — the primary tool for big migrating browns. Streamers in olive, black, and brown at first and last light and through shaded deep runs.

October

Peak month for trophy brown trout on the lower Madison. Spawning fish are in the river in numbers — target pre-spawn fish holding and feeding, not fish actively on redds. October caddis and olives on warmer afternoons. Streamer fishing through the canyon and the deep braids can be the best of the year.

October caddis - 8-12, large orange dry on warmer afternoons.
Mahogany dun and BWO on gray days.
Midges in slow water and tailouts.
Streamers — heavy, dark patterns through deep holding water. The canyon earns its reputation this month.

November

Spawn winding down. Post-spawn fish are recovering in deeper, slower water. BWO and midges on calm afternoons. Streamer fishing remains productive as fish are still concentrated from the run.

BWO and midges, 18-22.
Streamers in deep runs and canyon pools.
Small nymphs through tailouts.

December

Midge and streamer program. Cold water, short days. The lower braids near Three Forks are the most accessible option in winter.

Zebra midge and small nymphs.
Olive or black streamers in the deeper slots.

A western dry and nymph assortment covers the summer season. Add a full streamer box, hoppers, mahogany duns, and trico patterns for the complete lower Madison experience — and bring your biggest brown trout flies for September and October.