AuSable River Trout Fishing Conditions

The stretch anglers call the Holy Water runs for roughly twelve miles between Grayling and Mio. Designated as flies-only, catch-and-release water by the Michigan DNR, this section has protected its wild brown trout population for decades. Fish here are educated, the current is honest, and the hatches are legendary. If you can fool a brown trout on the Holy Water, you can fish anywhere.

The AuSable is a freestone river fed by cold springs throughout its length, which keeps water temperatures in the trout-prime range well into summer when other rivers warm past the threshold. This makes the Holy Water a mid-July destination when most anglers have given up on surface fishing until fall. The springs also give the river its characteristic clarity — polarized glasses and patience let you see fish before you cast to them.

Best Hatches on the AuSable

The AuSable hatch calendar is among the richest in the Midwest. Season opens in late April with Hendricksons emerging on warm afternoons — the Red Quill and Hendrickson Dry in sizes 12-14 fished in the afternoon between 2pm and 4pm will draw willing browns. May brings the Grannom caddis hatch in explosive numbers, and a well-skated Elk Hair Caddis on the surface can produce frantic takes.

Late June marks the arrival of the Hexagenia limbata — the Hex hatch. Massive, golden mayflies emerge after dark on warm, still evenings, drawing the largest brown trout in the river to the surface for several weeks. The AuSable Holy Water is ground zero for Hex fishing in Michigan. Anglers plan trips months in advance for this single event. Fishing an Extended Body Hex Dun on a moonless night to a slurping brown you can hear but not see is as thrilling as trout fishing gets.

Sulphurs follow the Hex into July, offering evening surface fishing through the peak of summer. White Fly emerges in August on the main stem. Fall brings the Blue-Winged Olive back for a second act, often coinciding with pre-spawn brown trout that are aggressive and highly visible in shallow riffles.

River Sections

The North Branch near Lovells holds exceptional wild brook trout in addition to browns. It is smaller and more technical than the main stem, requiring careful wading and shorter casts. The South Branch near Luzerne runs cold and clear through a different character of landscape — more remote and less pressured than the Holy Water. The main stem below Mio transitions toward a more migratory fishery with steelhead and walleye mixing in during their seasons.

Access and Regulations

The State of Michigan maintains numerous public access sites along the AuSable. Burton's Landing, Wakeley Bridge, Canoe Harbor, and Parmalee Bridge are among the most used on the Holy Water stretch. The DNR has made significant investments in public access infrastructure on this river over the past two decades, and most of the prime water is reachable without trespassing.

The Holy Water between Burton's Landing and Wakeley Bridge is flies-only, artificial lures only, catch-and-release year-round. The North Branch has its own special regulations. Check the current Michigan DNR Fishing Guide for exact boundaries before you fish. Regulations on the AuSable are enforced, and the conservation officers know the water.

When to Go

Season opens the last Saturday of April. The best fishing of the year is May through early July — Hendricksons, caddis, March Browns, and the build toward the Hex. Summer fishing remains surprisingly good given the spring-fed water temperatures. Fall in October brings aggressive pre-spawn browns and the second BWO hatch of the year. Some of the largest fish of the season are caught on streamers in October and early November before the season closes.