Au Sable River (South Branch)
Current Conditions
Flows are around 133 cfs and holding steady, about normal for late August. Water was 59°F at the gauge. The hatch calendar has Trico on this water in August.
Au Sable River (South Branch) Fishing Report
The South Branch Mason Tract is in prime form. Wild browns are rising to sulphurs and brown drakes in the evenings, and the Hex hatch is building — watch water temps. The remote stretches between Chase and Smith Bridge are producing the best fish. Plan for a full-day wade-in — this is not a river you rush.
Live Flow Conditions
Hatch Calendar
Gear Recommendations
| Gear | fly Dry FlyRecommended | rod Nymphing | rod Euro Nymph | fish Streamer |
|---|---|---|---|---|
| Rod | 9ft 4-weight or 5-weight | 9ft 5-weight | 10.5ft 3-weight | 9ft 6-weight |
| Line | DT4F or WF5F floating | WF floating | Euro mono rig | WF floating or intermediate |
| Leader | 12ft tapered leader | 9ft to 4X | Long mono rig | 6ft to 1X |
| Tippet | 5X–6X fluorocarbon | 5X–6X | 6X fluorocarbon | 1X–2X |
| Waders | Chest waders (hip waders workable in summer) | Chest waders | Chest waders | Chest waders |
| Boots | Felt-soled or rubber wading boots | Felt-soled boots | Felt-soled boots | Felt-soled boots |
Find Your Guide
Local Fly Shops
Public Access Points
River History & Character
The South Branch of the Au Sable flows through what is arguably the most storied piece of fly fishing real estate in Michigan — the Mason Tract. This 1,500-acre wilderness preserve was gifted to the State of Michigan by auto executive Chase Salmon Osborn and later championed by Detroit newspaper publisher George Mason, whose estate donated the core 1,500 acres of wild river corridor in 1954. The South Branch winds for miles through remote cedar swamp and jack pine forest without a road crossing, creating a true wilderness wading experience rarely found in the Lower Peninsula. The river is designated flies-only and catch-and-release throughout much of the Mason Tract, and its population of large, wild brown trout rivals any stream in the state. The river runs cold, clear, and spring-fed year-round, making it one of the most thermally stable branches of the Au Sable system.