FISHABLE
Water temp 32°F (0.4°C), ice-affected gauges but spring-fed flows remain stable. Browns feeding in afternoon. Best fishing noon-dark.Au Sable River
Current Hatch Activity
Midge activity on warmer afternoons when water temps creep above 33°F. Fish black streamers with slow strips in deeper runs or nymph the slow pools with small mayfly patterns (#16-20). Best window is noon to late afternoon. USGS gauges ice-affected but spring-fed character keeps flows fishable.
FISHABLE
Black streamer (Woolly Bugger #6-8, Zoo Cougar #4) slow-stripped, or nymph rig with Pheasant Tail #16-18 + Zebra Midge #20-22 in deeper pools
Quick Reference
100 CFS at Grayling, 550 CFS at Red Oak, 1,100 CFS at Mio typical. Wade safely up to 1,300 CFS. Above 1,600 CFS requires a boat.
45-65°F optimal. Spring-fed origins keep temps remarkably stable—one of the most consistent rivers in the country.
Spring-fed stability means consistent hatches and predictable fishing. High flows in spring from snowmelt, but the river returns to normal quickly.
Exceptional clarity due to spring-fed origins. Clear water year-round except during extreme high-water events.
What "Fishable" Means Here
Arguably the finest brown trout water east of the Rockies. Trophy browns, brook trout, and rainbows throughout 100 miles of river. The 'Holy Waters' section is fly-only, catch-and-release.
Seasonal Patterns
spring
March through May brings excellent hatches. Hendricksons, Sulphurs, and March Browns draw fish up. The Au Sable's legendary hatches begin here.
summer
June through August features prolific hatches. Hex hatches in June are world-famous. Tricos, terrestrials, and night fishing for trophy browns. This is prime time.
fall
September through November sees brown trout spawning activity. Streamers produce trophy fish. BWOs and October caddis provide dry fly opportunities. Less crowded.
winter
December through February offers solitary fishing. Browns remain active. Midges and small nymphs in slower water. The river rewards patient, technical anglers.
Alerts
Alternative Waters
Pere Marquette River
Michigan alternative with salmon and steelhead optionsManistee River
Larger water nearby with diverse fishing opportunitiesRiver Intel Weekly
Weekly flow updates and fishing intel.
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