Au Sable River
Fly fishing in Michigan · Intermediate · Best seasons: Spring, Summer, Fall
Target Species
Brown Trout, Brook Trout
About This Water
The Holy Water section is legendary for brown trout. Birthplace of Trout Unlimited.
Fishing Recommendations
The Au Sable River in Michigan is hallowed ground for fly anglers. Often referred to as the "Holy Waters," this river is the birthplace of Trout Unlimited and represents the pinnacle of Midwestern trout fishing. As your guide, I’m excited to break down why this river is a "bucket list" destination.
🎣 Location Overview
The Au Sable is a classic freestone-style river (though influenced by groundwater) that flows through the sandy pine barrens of Northern Lower Michigan. It is divided into three primary branches: the Main Stream, the North Branch, and the South Branch.
What makes it special is its stability. The sandy soil of the region acts as a massive filter, providing consistent cold-water temperatures and steady flows. The river is famous for its "cedar-sweepers"—fallen trees that line the banks, providing world-class cover for trout. The most famous stretch is the "Holy Waters," a 9-mile section from Burton’s Landing to Stephan Bridge that is strictly catch-and-release and "flies only."
🐟 Target Species & Behavior
- Brook Trout: These are the native gems of the Au Sable. You’ll find them in the colder headwaters and throughout the North and South branches. They are opportunistic feeders and will often rise to a dry fly even when no hatch is present. Look for them in faster ripples and near cold-water springs.
- Brown Trout: The Au Sable's browns are legendary for their size and wariness. While small browns are plentiful, the "trophy" fish (20"+) are primarily nocturnal. They hold deep in submerged log jams (structure is king here) and move into the shallows to feed during heavy hatches or under the cover of darkness.
📅 Best Times to Fish
- Spring (Late April – May): This is the start of the major hatch cycle. The Hendrickson hatch in late April/early May is the first big event of the year, bringing the larger fish to the surface during the afternoon.
- Summer (June – July): This is "Prime Time."
- The Hex: Late June to early July features the Hexagenia limbata (Giant Michigan Mayfly) hatch. This is a nocturnal event where the largest browns in the river feed on the surface.
- Terrestrials: August is fantastic for fishing ants, beetles, and grasshoppers along the cedar banks.
- Fall (September – October): As temperatures cool, the browns become aggressive as they prepare for the spawn. This is the best time for streamer fishing.
- Time of Day: During the heat of summer, midday fishing is slow. Focus on the "Magic Hour" (dusk) or go "Mousing" (fishing mouse patterns) from 11 PM to 3 AM.
🪰 Recommended Flies & Techniques
Top Fly Patterns
- Dry Flies: Roberts Yellow Drake (a local legend), Borchers Special, Adams (the original was tied nearby), Hendrickson (Dark and Light), and the massive Hexagenia patterns.
- Nymphs: Pheasant Tail (#14-18), Prince Nymph (#12-16), and the Au Sable Nano Krill.
- Streamers: Kelly Galloup’s Dungeon, Sculpin patterns, and the Zoo Cougar.
- Mousing: Master Splinter or any foam-backed mouse pattern.
Techniques
- The Reach Cast: The Au Sable has many micro-currents. A reach cast is essential to get a drag-free drift before your line gets pulled by the current.
- Pound the Wood: When fishing streamers or terrestrials, you must get your fly within inches of the fallen cedar trees. If you aren't snagging wood occasionally, you aren't fishing where the big browns live.
- Dry-Dropper: In the summer, a buoyant foam fly (like a Chubby Chernobyl) with a small pheasant tail dropper is deadly for Brookies.
💡 Pro Tips & Local Knowledge
- The "Au Sable River Boat": This is a unique, long, narrow wooden boat designed specifically for this river. If you have the chance to fish from one with a guide, do it—it’s the most traditional way to experience the water.
- Night Fishing (Mousing): Michigan is the home of modern mousing. Use a short, heavy leader (0X or 12lb fluorocarbon). Cast toward the bank and listen for the "slurp." Don't set the hook until you feel the weight of the fish.
- The Mason Tract: If you want solitude, hike into the Mason Tract on the South Branch. It is a scenic, undeveloped wilderness area with fantastic Brookie fishing.
- Sand is a Treadmill: The bottom is mostly sand and gravel. It’s easy wading, but the sand can shift. Use a wading staff if you are unfamiliar with the stretch.
⚠️ Important Information
- Regulations: Michigan has complex trout regulations. Many sections of the Au Sable are "Gear Restricted" (Artificial Lures/Flies only) and "Catch and Release Only." Always check the MDNR Trout Water Maps before casting.
- Licensing: You need a Michigan Fishing License (All-Species). You can buy these online or at local shops in Grayling or Mio.
- Etiquette: The Au Sable is a popular river. If you see another angler, give them plenty of space (at least two bends of the river). If you are floating, yield to the wading anglers by passing quietly behind them.
- Local Shops: Stop by Gates Au Sable Lodge or The Old Au Sable Fly Shop in Grayling. These are the hubs of local knowledge and will tell you exactly what is hatching that hour.
Bug Hatches & Matching Flies
| Hatch | Type | Peak months | Time of day | Hook sizes | Matching flies |
|---|---|---|---|---|---|
| Hendrickson Ephemerella subvariabilis | mayfly | April, May | Afternoon | #12-14 | Red Quill #12-14, Hendrickson Emerger #12-14, Pheasant Tail #12-14 |
| Blue Winged Olive Baetis spp. | mayfly | April, May, September, October | Overcast Afternoons | #18-22 | BWO Sparkle Dun #18-22, RS2 #20-22, BWO Parachute #18-20 |
| Grannom Caddis Brachycentrus | caddis | April, May | Mid-day | #14-16 | Grannom Pupa #14-16, Elk Hair Caddis (Olive/Grey) #14-16, Peacock Caddis #16 |
| Sulphur Ephemerella invaria/rotunda | mayfly | May, June | Evening | #14-18 | Sulphur Parachute #16-18, CDC Sulphur Emerger #14-18, Roberts Yellow Drake #14-16 |
| Brown Drake Ephemera simulans | mayfly | June | Dusk | #10-12 | Brown Drake Paradun #10-12, Brown Drake Spinner #10-12, Borchers Special #12 |
| Hex (Giant Michigan Mayfly) Hexagenia limbata | mayfly | June, July | Night | #4-8 | Hexagenia Spinner #4-6, Hex Paradrake #6-8, Wiggle Hex Nymph #6 |
| Isonychia (Slate Drake) Isonychia bicolor | mayfly | June, July, August, September | Late Afternoon | #10-12 | Iso Parachute #10-12, Zug Bug #10-12, Prince Nymph #10-14 |
| Trico Tricorythodes spp. | mayfly | July, August, September | Morning | #20-24 | Trico Spinner #20-24, Trico Drowned Spinner #22, Griffith's Gnat #20-22 |
| White Miller Ephoron leukon | mayfly | August | Late Evening | #12-14 | White Wulff #12-14, Ephoron Spinner #14, Light Cahill #14 |