Au Sable River

The Au Sable River flows roughly 138 miles across the northern Lower Peninsula of Michigan, gathering near Grayling and winding east through pine and hardwood country to empty into Lake Huron at Oscoda. Cold, clear and spring-fed, it is one of the most celebrated trout streams in the eastern United States.

The upper river — the famous “Holy Waters” below Grayling — is a fly-fishing shrine for wild brown trout, with a flies-only, catch-and-release ethic that helped launch the modern conservation movement; Trout Unlimited was founded on the Au Sable in 1959. The river also gave rise to the distinctive Au Sable riverboat, a long, shallow-draft wooden craft built for guiding anglers.

Beyond fishing, the Au Sable is a paddler's river, host to the grueling overnight Au Sable River Canoe Marathon, and a recreation corridor of state forest campgrounds, riverside trails and a National Scenic Byway. Much of its length is protected as a Michigan Natural River and a federally designated Wild and Scenic River.

Fly fishing for wild brown trout is the Au Sable's signature pursuit, centered on the catch-and-release Holy Waters below Grayling, but the river is just as loved by paddlers. Canoe and kayak liveries line the upper river, and the annual Au Sable River Canoe Marathon sends racers 120 miles through the night from Grayling to Oscoda.

State forest campgrounds, riverside trails and the River Road National Scenic Byway near the mouth add hiking, camping and wildlife viewing. The lower river's impoundments offer flatwater paddling and warmwater fishing as well.

Late spring through early summer brings the famous mayfly hatches — including the storied Hex hatch — and the best dry-fly fishing, while summer is prime for paddling the cool river on a hot day. Fall pairs good fishing with brilliant color along the banks.

Winter slows the river to a quiet, snowy corridor, though hardy anglers still fish the open, spring-fed upper stretches. Check Michigan DNR seasons and gear rules before you go.

The Au Sable was a travel and fishing route for the Anishinaabe long before the logging boom of the late 1800s, when white pine was floated down the river to mills and the surrounding forests were cut over. As the cutover land recovered, the river became famous for trout.

In 1959 a group of anglers gathered on the Au Sable to found Trout Unlimited, launching a national coldwater-conservation movement. The river's flies-only traditions and its purpose-built riverboats remain part of its living heritage.

The Au Sable is a classic spring-fed river: rain and snowmelt percolate through the sandy glacial outwash of the northern Lower Peninsula and emerge as cold, steady groundwater that keeps the river cool and clear even in summer — ideal trout conditions.

That sandy, glacially deposited landscape, left by the retreat of the last ice sheet, gives the river its stable flow and gravel runs, while a series of downstream dams creates the impoundments of the lower river.

The Au Sable corridor is excellent for wildlife watching: look for bald eagles, ospreys and great blue herons over the water, and beaver and otter along the banks at dawn and dusk. The surrounding jack-pine forests are the world's primary nesting ground for the endangered Kirtland's warbler, a bird-watching draw each spring.

Cold, clean water makes the Au Sable a stronghold for wild brown trout, along with brook and rainbow trout in places. The river corridor of cedar, pine and hardwood supports a rich web of life from mayflies to mammals.

Beaver, river otter, white-tailed deer and black bear range the banks; bald eagles, ospreys, herons and kingfishers hunt the water; and the river is part of the recovery range of the rare Kirtland's warbler, which nests in the surrounding jack-pine country.

The Au Sable is one of Michigan's premier trout rivers. The catch-and-release, flies-only Holy Waters from Burton's Landing to Wakeley Bridge hold strong populations of wild brown trout and are best known for prolific evening mayfly hatches in late spring and early summer.

Below the special-regulation water, the river offers a mix of trout and, in the impoundments, warmwater species. Always confirm current Michigan DNR gear, season and limit regulations for the stretch you plan to fish.

The river runs through Anishinaabe homeland and carries a deep angling culture that shaped American conservation. As the birthplace of Trout Unlimited and home of the Au Sable riverboat and the storied canoe marathon, it holds an outsized place in Michigan's outdoor identity.

Grayling, on Interstate 75 in the north-central Lower Peninsula, is the gateway to the upper river and its liveries, fly shops and the Holy Waters. The river then runs east through Mio and along the River Road Scenic Byway to its mouth at Oscoda on Lake Huron.

Dozens of public access sites, state forest campgrounds and bridges provide put-ins and take-outs along the way; a Michigan Recreation Passport is needed for state-managed sites.

The Au Sable's health rests on its cold groundwater and clean gravel, so protecting the watershed from sedimentation, warming and pollution is vital. Catch-and-release regulations, riverbank restoration and the work of groups like Trout Unlimited and the Anglers of the Au Sable help keep the fishery strong.

Much of the river is protected as a Michigan Natural River and a Wild and Scenic River, guarding its character against development.

The water is cold year-round — wear appropriate gear and watch for hypothermia on long paddles or wades, especially in spring. Currents, sweepers (fallen trees) and the dams on the lower river all demand caution; portage around dams and scout unfamiliar water.

Wading anglers should use a staff and felt-free traction, and everyone should carry insect protection during the heavy early-summer hatches.

Fishing is governed by Michigan DNR regulations, which vary by stretch — parts of the upper river are flies-only and catch-and-release, with special seasons and gear rules. A Michigan fishing license is required.

State forest campgrounds and access sites follow standard rules; a Recreation Passport is required for vehicle entry at state-managed sites, and dams must be portaged. Respect private land along the banks.

Grayling anchors the upper river, near Hartwick Pines State Park and its old-growth white pines. Downstream, Mio and the River Road Scenic Byway lead to Lumberman's Monument and the Lake Huron shore at Oscoda.

The surrounding Huron-Manistee National Forests, the Kirtland's warbler country, and the nearby South Branch (the “Mason Tract”) give anglers and paddlers a whole region to explore.

For the classic Au Sable experience, fish or float the Holy Waters below Grayling, and time a late-spring or early-summer evening for the mayfly hatches. Book liveries and lodging early around the July canoe marathon, when Grayling fills up.

Bring layers and bug protection, learn the catch-and-release rules before you cast, and consider hiring a guide and an Au Sable riverboat for a true taste of the river's tradition.