Au Sable South Branch
🍃 Natural River
Crawford / Roscommon Co. · 40 mi · Class Riffles
512CFS/ 5.93 ft
Above Optimal→Stable
Water temp: 44°F — Hypothermia risk, wear a drysuit
Optimal: 100–400 CFS · USGS #04135700
Length
Difficulty
Optimal
Avg Flow
Hist. Median
USGS Gauge
Michigan Natural River
Quieter and more intimate than the main stem Au Sable, the South Branch winds through state forest with wild brook trout in every pool. A peaceful escape for anglers and paddlers seeking solitude. Designated a Michigan Natural River, the 40-mile South Branch is narrowest and wildest from Chase Bridge to Smith Bridge before widening on the lower reach to Roscommon.
Trip sections
Chase Bridge to Smith Bridge — upper reach, narrow and wild
Smith Bridge to Roscommon — lower reach, wider meanders
Outfitters
South Branch Canoe Livery
Canoe and kayak rentals on the South Branch
72-Hour Flow Forecast
NOAA NWPSLoading forecast...
10-Year Flow Patterns
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Your Optimal Range
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Data Quality
River conditions are community-verified. CFS ranges, difficulty ratings, and trip sections may not reflect every flow level or seasonal change. Always check current conditions, scout unfamiliar rapids, and paddle within your skill level. If you spot an error, use the Improve This River button at the top of the page — your local knowledge is what makes this atlas accurate.