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The Holy Water and beyond. Grayling to Mio, Michigan's most storied trout river. The river tops out around 8 ft. The contours are modeled from the water's real shoreline and maximum depth. Treat them as a rough guide, and never use them for navigation. The season-by-season read for each species follows, from the map's own numbers.
The outline encloses 1,754 acres, worked by 75.4 miles of shoreline. The 12.9 development index tells the story — a convoluted bank whose fishable edge far outruns the acreage. Nothing on this chart breaks 15 ft, which makes the whole surface littoral: weeds, bait and ambush cover everywhere. Call it 28.5 mi long by 2 mi wide at the broadest reach. It sits in Crawford County. Frog Lake (central) sits 10 mi northwest — the closest neighbouring chart.
Start shallow in spring: brown trout sit in 1 to 8 ft that time of year. They don't go far with the seasons — 2 to 8 ft covers summer, 1 to 8 ft covers winter. Top water on the chart: Current seam (mile 5.6), a current seam in the 4 ft range, prime in summer. Fish it in after dark and early morning and you'll meet the bite. Throw a spoon at the thermocline or a deep stickbait (night) until the fish tell you otherwise.
Depth note: when a documented seasonal range extends below this chart, the table shows the deepest mapped working water, not a verified holding depth.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 1 to 8 ft chart-limited; documented 3 to 25 ft | dawn & dusk | Mio Dam tailrace (7 ft) | Stickbait off planer boards (shallow), Small spoon along mud lines |
| Summer | 2 to 8 ft chart-limited; documented 25 to 60 ft | night & dawn | Current seam (mile 5.6) (4 ft) | Spoon at the thermocline, Deep stickbait (night) |
| Fall | 1 to 8 ft chart-limited; documented 5 to 30 ft | dusk & dawn | Mio Dam tailrace (7 ft) | Jerkbait over gravel, Casting spoon |
| Winter | 1 to 8 ft chart-limited; documented 5 to 35 ft | dawn | Mio Dam tailrace (7 ft) | Jigging spoon, Small stickbait (slow) |
When the water first warms, brook trout slide up into 1 to 8 ft. There's no big seasonal slide here — summer means 2 to 8 ft, winter 1 to 8 ft. If you only fish one area, make it Current seam (mile 5.6): a current seam around 4 ft that scores prime in spring. In summer the feeding windows fall in early morning and the evening. Keep a small spoon fished deep or a trolled lake-clear wobbler + worm rigged through the warm months.
Depth note: when a documented seasonal range extends below this chart, the table shows the deepest mapped working water, not a verified holding depth.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 1 to 8 ft chart-limited; documented 2 to 15 ft | dawn & dusk | Current seam (mile 5.6) (4 ft) | Small inline spinner (gold), Tiny spoon |
| Summer | 2 to 8 ft chart-limited; documented 10 to 30 ft | dawn & dusk | Current seam (mile 5.6) (4 ft) | Small spoon fished deep, Trolled lake-clear wobbler + worm |
| Fall | 1 to 8 ft chart-limited; documented 2 to 15 ft | midday & dawn | Current seam (mile 5.6) (4 ft) | Small spoon (orange), Spinner |
| Winter | 1 to 8 ft chart-limited; documented 3 to 20 ft | dawn | Current seam (mile 5.6) (4 ft) | Small jigging spoon, Tungsten jig + plastic |
Come spring, look for rainbow trout tight to the bank in 2 to 8 ft. Through summer count on 2 to 8 ft; the winter hold is 2 to 8 ft. Start at Current seam (mile 5.6). It's a current seam holding about 4 ft of water and rates prime come spring. Prime time lands in early morning and the evening. A dodger + spoon (deep troll) or a flutter spoon is the honest summer answer here.
Depth note: when a documented seasonal range extends below this chart, the table shows the deepest mapped working water, not a verified holding depth.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 2 to 8 ft chart-limited; documented 5 to 20 ft | dawn & dusk | Current seam (mile 5.6) (4 ft) | Inline spinner (silver), Small spoon |
| Summer | 2 to 8 ft chart-limited; documented 8 to 30 ft | dawn & dusk | Current seam (mile 5.6) (4 ft) | Dodger + spoon (deep troll), Flutter spoon |
| Fall | 2 to 8 ft chart-limited; documented 10 to 35 ft | dawn & dusk | Current seam (mile 5.6) (4 ft) | Casting spoon, Jerkbait over shoals |
| Winter | 2 to 8 ft chart-limited; documented 8 to 40 ft | dawn | Current seam (mile 5.6) (4 ft) | Jigging spoon, Tube jig (white) |
Spring puts rock bass in skinny water — 2 to 8 ft is the zone. Summer fish stay in 2 to 8 ft, and winter fish hold in 2 to 8 ft. Spring rock bass concentrate at Riffle & run (mile 10.0), a prime-rated rock pile around 3 ft. Warm-month bites cluster around the evening. A ned rig (small) or a marabou jig covers the summer program.
Depth note: when a documented seasonal range extends below this chart, the table shows the deepest mapped working water, not a verified holding depth.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 2 to 8 ft chart-limited; documented 2 to 10 ft | midday & dawn | Riffle & run (mile 10.0) (3 ft) | 1/16 oz jig + grub, Small inline spinner |
| Summer | 2 to 8 ft chart-limited; documented 5 to 20 ft | dusk | Riffle & run (mile 10.0) (3 ft) | Ned rig (small), Marabou jig |
| Fall | 2 to 8 ft chart-limited; documented 8 to 22 ft | midday | Riffle & run (mile 10.0) (3 ft) | Small tube jig, Inline spinner |
| Winter | 2 to 8 ft chart-limited; documented 12 to 30 ft | midday | Riffle & run (mile 10.0) (3 ft) | Tungsten jig + plastic, Small spoon + spike |
In spring, atlantic salmon run shallow here, mostly 1 to 8 ft. Summer keeps them at 2 to 8 ft, and they winter in 2 to 8 ft. Current seam (mile 5.6) is the standout, a current seam at roughly 4 ft, rated prime for spring atlantic salmon. Time it for early morning and the evening. You won't need more than a trolling spoon or a flasher + fly most summer days.
Depth note: when a documented seasonal range extends below this chart, the table shows the deepest mapped working water, not a verified holding depth.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 1 to 8 ft chart-limited; documented 5 to 30 ft | dawn & dusk | Current seam (mile 5.6) (4 ft) | Slim coastal spoon, Trolling spoon |
| Summer | 2 to 8 ft chart-limited; documented 20 to 70 ft | dawn & dusk | Tailout eddy (mile 37.6) (4 ft) | Trolling spoon, Flasher + fly |
| Fall | 1 to 8 ft chart-limited; documented 4 to 28 ft | dawn & dusk | Current seam (mile 5.6) (4 ft) | Casting spoon, Large streamer |
| Winter | 2 to 8 ft chart-limited; documented 10 to 45 ft | midday | Current seam (mile 5.6) (4 ft) | Slow coastal spoon |
Early season coho salmon use the shallows, holding in 1 to 8 ft. Even in summer they hold at 2 to 8 ft; winter keeps them in 2 to 8 ft. The chart's best answer is Mio Dam tailrace — dam tailrace, 7 ft, prime for spring. Best bite is early morning and the evening. Tie on a dodger + fly or a medium spoon above the thermocline and you're in the game.
Depth note: when a documented seasonal range extends below this chart, the table shows the deepest mapped working water, not a verified holding depth.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 1 to 8 ft chart-limited; documented 3 to 25 ft | dawn & dusk | Mio Dam tailrace (7 ft) | Small orange dodger + peanut fly, Thin spoon (orange/silver) |
| Summer | 2 to 8 ft chart-limited; documented 30 to 70 ft | dawn & dusk | Mio Dam tailrace (7 ft) | Dodger + fly, Medium spoon above the thermocline |
| Fall | 2 to 8 ft chart-limited; documented 8 to 40 ft | dawn & dusk | Mio Dam tailrace (7 ft) | Casting spoon, Spinner (chartreuse) |
| Winter | 2 to 8 ft chart-limited; documented 20 to 60 ft | midday | Mio Dam tailrace (7 ft) | Small spoon, slow troll |
Au Sable River carries 30 mapped structure features, topping out (or rather bottoming out) at Mio Dam tailrace, about 7 ft down.
Access data: Michigan DNR — Michigan Boating Access Sites. Confirm conditions and fees locally before you launch.
| Date | Species | Count | Size |
|---|---|---|---|
| Jun 1 | Rainbow trout | 5,076 | ~19.5" |
| May 20 | Rainbow trout | 37,117 | ~18.4" |
| May 18 | Rainbow trout | 34,133 | ~19.1" |
| May 13 | Atlantic salmon | 29,498 | ~19.4" |
| May 11 | Atlantic salmon | 7,750 | ~17" |
| Apr 29 | Rainbow trout | 3,100 | ~20" |
| Apr 29 | Rainbow trout | 3,099 | ~20" |
| Apr 28 | Rainbow trout | 5,699 | ~19.5" |
Source: Michigan DNR fish-stocking database, retrieved 2026-09-23.
Season dates, license requirements, and size and bag limits for Michigan waters are set by the Michigan DNR — and special regulations can apply to Au Sable River specifically, so confirm the current rules before you fish.
Check the official Michigan fishing regulations →
Au Sable River is about 8 ft (2 m) deep at its deepest point. The contours here are modeled from the water's real shape and maximum depth, so treat them as a rough guide.
Anglers target brown trout, brook trout, rainbow trout, rock bass, atlantic salmon, coho salmon on Au Sable River.
Current seam (mile 5.6) is the top-rated area: a current seam in about 4 ft of water that rates prime for rainbow trout in spring. Every other rated spot, per species and season, is on the map above.
For brown trout, the summer bite is best in after dark and early morning. Each species page section below lists the seasonal windows, and the map shows a live NOW badge when you're inside one.
Yes — per Michigan DNR fish-stocking database records, Au Sable River was most recently stocked Jun 1 with 5,076 rainbow trout. The full stocking history is listed above.
Fishing on Au Sable River is regulated by the Michigan DNR. Check the official Michigan regulations for current license requirements, season dates, and size and bag limits — special regulations can apply to this specific water.
Frog Lake (central) 10 mi · KP Lake 11 mi · Muskrat Lake 11 mi · Shupac Lake 11 mi · Jones Lake 12 mi · Little Bear Lake 12 mi · Shellenbarger Lake 13 mi · Snyder Lake 13 mi · Bear Lake 13 mi · Tea Lake 14 mi · Moon Lake 14 mi · West Twin Lake 15 mi
See how Au Sable River stacks up: best rainbow trout lakes in Michigan · best coho salmon lakes in Michigan · best brown trout lakes in Michigan · best brook trout lakes in Michigan
More water nearby: Crawford County fishing maps (11 charts). Browse all Michigan fishing maps. See every water on DepthScout. How we build these maps. Fish here with a sonar unit that logs? Send us your depth data and we'll improve this chart, credited to you. For fishing guidance only, never navigation.