Chris Izworski, reporting from Michigan on the current state of the Au Gres River, finds a stream running slightly elevated for late September but well within fishable range. The gauge at the U.S. 23 crossing reads 37 cubic feet per second, which puts today at 112 percent of the historical median for this date. The water is moving with a touch more authority than usual, but not so much that it should deter anyone considering the drive into Arenac County.

Why the Au Gres Matters in September

The Au Gres is the sort of river that gets overlooked while anglers make the pilgrimage to more famous names. It flows through the northeastern Lower Peninsula on its way to Saginaw Bay, and the upper reaches, where the water comes cold and clean from the Ogemaw Hills, hold genuine brown trout and the occasional steelhead. September is when this river becomes worth your time. The water has cooled enough that browns begin thinking about spawning grounds. The crowds have thinned to almost nothing. If you fish here now, you fish alone or nearly so, which changes everything about what the river offers.

The freestone character means the Au Gres responds quickly to rain and runoff, but it also clears relatively fast once the rain stops. Access from the Au Gres area and along Arenac County roads gives you options without the parking-lot complications of southern Michigan’s most popular streams. Check current steelhead regulations before you go, as this is classified as a Saginaw Bay tributary, but general trout rules apply to browns.

Reading Today’s Water

At 37 cfs, the river sits just slightly above where it typically runs on September 22. This is not a problem. The gauge height of 5.2 feet tells you the stream is moving purposefully through its channel without pushing into the banks or turning murky. Browns will be in their usual September positions: in the deeper runs, behind structure, in the softer water along the banks where they can hold without fighting current all day. The slightly elevated flow means they may be less spooky than they would be in drought conditions, though you will still need to fish carefully. Cold water and spawning season make them cautious.

Water temperature data from the gauge is unavailable today, but at this time of year, expect the upper sections to be in the low to mid-50s Fahrenheit. Cool enough to keep trout active and interested in food, which matters for your fly selection and presentation.

Hatches Worth Your Time

September on the Au Gres centers on small mayflies and the opportunistic fishing that comes with them. Blue-winged olives are your bread and butter. They emerge in small numbers throughout the day when conditions stay overcast and cool, which late September often delivers. Fish a Parachute BWO in size 16 or a Sparkle Dun, keeping your tippet to 5X or 6X and working deliberately through the runs. If the hatch gets heavy enough to pull fish up, switch to an RS2 nymph fished just below the surface. The rise forms will be subtle, so watch the specific seam you are fishing rather than scanning the whole river.

Tricos appear in the pre-dawn hours, and if you are willing to be on the water by first light, the spinner fall from roughly sunrise to 9 a.m. can produce aggressive fishing. This is size 20 work with 6X or 7X tippet and a long leader. Choose a single rising fish and present to it repeatedly rather than covering water. CDC Trico Spinners and Poly Wing Tricos are the right patterns.

Fall caddis are also active in the afternoons. Orange Elk Hair Caddis in size 14 works both as an attractor and as a reasonable match to what is actually emerging. Fish the runs and riffles with a slight skating motion. Terrestrials, too, have their place along the grassy and undercut banks. A foam beetle tight to the bank, allowed to sit or given just the smallest twitch, can produce surprise takes from fish that have seen nothing but drifting nymphs all summer.

The Evening Window

Sunset today comes at 7:34 p.m., with the best dry-fly window running from roughly 6:04 p.m. through dark. This is when blue-winged olives and fall caddis often produce their heaviest hatches. If you can be on the water from mid-afternoon through the evening, you will have caught the two best windows of the day: the afternoon emergence and the longer golden hour. The water will still be cool and responsive as light fades.

The Honest Read

The Au Gres is fishing well today. The conditions rating confirms it: worth the drive. You are not fighting high water, and you are not dealing with the blown-out conditions that plague other freestone streams when September rain stacks up. The fish are present, the hatches are on, and solitude is almost guaranteed. If you are within reasonable striking distance of Arenac County, this is a day to go.

For live gauge data and updates, check https://michigantroutreport.com.