Chris Izworski, reporting from Michigan on the current state of the Thunder Bay River, finds conditions that deserve serious consideration from anglers willing to make the drive to Alpena County. The river is running at 528 cubic feet per second, nearly dead on the historical median for this date, which places it in that sweet spot where a trout angler can actually fish without fighting water that’s either too low or running away from you. The gauge height of 12.24 feet tells you nothing profound on its own, but paired with the flow data it confirms that the Thunder Bay is tracking normally for early May. This river does not get the press that the Au Sable or Manistee command, and that fact alone makes it worth knowing.

Why the Thunder Bay Gets Overlooked

The Thunder Bay flows through northeast lower Michigan in a region that doesn’t have the same tradition of trout tourism as the mainstream rivers further south. The access points around Herron, Bolton, and the Atlanta region upper reaches exist quietly, without the infrastructure of crowded parking areas and worn footpaths that define the more famous water. If you fish here, you are making a deliberate choice rather than following a guidebook recommendation. That choice, right now, is paying off. The systematic conditions rating for today is Fishing Well, and the tagline attached to it is straightforward: Worth the drive.

This is not hyperbole designed to fill column space. The river holds brown trout in its upper reaches and steelhead in the lower sections as it flows toward Lake Huron, making it a true freestone with character and variety. Browns in the upper water, the possibility of chrome in the lower sections, and minimal pressure from other anglers. The Thunder Bay remains underutilized and underappreciated, which in May, when the serious hatches are building, translates to an afternoon where you might actually be alone on water holding feeding fish.

The May Hatch Window and Tonight’s Opportunity

Early May on a Michigan trout stream is when the Hendricksons fade but the sulphurs, caddis, and stoneflies begin their sustained push. The Blue-Winged Olives will be emerging during overcast stretches, which you should fish with emerger patterns like the RS2 in size 18 on fine 5X or 6X fluorocarbon tippet. The real event, however, arrives this evening. The sulphur hatch typically peaks from 7 to 9 p.m. on northeast Michigan rivers, and your golden hour window tonight runs from 7:17 p.m. to sunset at 8:47 p.m. You have a 90-minute window where the light quality is ideal and the bugs are coming off the water. Fish the Comparadun or Parachute in size 14, and if the hatch becomes heavy, switch to a Sparkle Dun in size 16 and focus on the rise lanes in the flat water.

The Grannom caddis are also active, and if conditions remain overcast through the afternoon, you should have opportunity with the Elk Hair Caddis in size 14, skittered across the surface in the riffles. The Early Brown Stoneflies are present too, meaning the wet fly and nymph option remains viable throughout the day. A Hare’s Ear Nymph in size 12 swung through fast water can connect fish before the dry fly window even opens.

Flow, Temperature, and Your Decision

The water temperature data from the USGS gauge is not available today, which means you should plan to arrive early enough to feel the water yourself and observe what the trout are doing. The flow of 528 cfs running at 99 percent of the historical median suggests stable conditions, unlikely to change dramatically unless significant rain arrives in the forecast. The river is in the middle 50 percent of its typical range for May 7, which is exactly where you want it: not too high, not too low, with good definition in the current and readable water structure.

Check the current steelhead regulations for Lake Huron tributaries before you go, as the general trout rules apply but steelhead seasons and restrictions can shift. Access the upper reaches around Atlanta and Bolton for brown trout, then decide whether the lower sections near Herron are worth your time based on what you learn about current steelhead conditions.

The Thunder Bay is fishing well today and the drive is justified. Plan to be on the water by mid-afternoon, focus on the nymph and wet fly until the sulphur emergence begins, then shift to dry flies for the evening window. This river will reward attention and a willingness to explore water that doesn’t appear on every angler’s mental map.

For live gauge data and detailed flow information, check https://michigantroutreport.com.