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226-acre lake in Judith Basin County, Montana. The lake tops out around 39 ft. The depth chart is built from real state fisheries GPS surveys, so the humps, channels and drop-offs you see are measured, not guessed. Here's the year, species by species, as the scoring engine sees it.
Drawn out, this is 226 acres of water rimmed by 2.2 miles of bank. Its 1.1 shoreline index means few bank features; the contours below do the pattern work. Roughly 20% of the water is 15 ft or less, the band where the food chain lives. Tip to tip the water measures near 0.9 mi with a 0.5-mi widest point. The water lies in Judith Basin County. Closest neighbour on DepthScout: Crystal Lake (Fergus), 23 mi southeast of here.
In spring, rainbow trout run shallow here, mostly 5 to 20 ft. Midsummer fish sit out in 8 to 30 ft before dropping to 8 to 39 ft for winter. Winter rainbow trout concentrate at Break off the point, a prime-rated drop-off around 33 ft. Fish it in early morning and the evening and you'll meet the bite. You won't need more than a dodger + spoon (deep troll) or a flutter spoon most summer days.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 5 to 20 ft | dawn & dusk | Main-lake point (7 ft) | Inline spinner (silver), Small spoon |
| Summer | 8 to 30 ft | dawn & dusk | Break off the point (33 ft) | Dodger + spoon (deep troll), Flutter spoon |
| Fall | 10 to 35 ft | dawn & dusk | Secondary point (8 ft) | Casting spoon, Jerkbait over shoals |
| Winter | 8 to 39 ft | dawn | Break off the point (33 ft) | Jigging spoon, Tube jig (white) |
Spring puts kokanee in skinny water — 10 to 30 ft is the zone. Warm water sends them out to 12 to 39 ft; cold water stacks them in 10 to 39 ft. Deep basin is the standout, a deep basin at roughly 39 ft, rated prime for summer kokanee. Plan around early morning in the warm months. A dodger + pink/orange squid on downrigger or a kokanee bug + corn covers the summer program.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 10 to 30 ft | dawn | Break off the point (33 ft) | Small dodger + squid (pink), Wedding-ring spinner + corn |
| Summer | 12 to 39 ft | dawn | Deep basin (39 ft) | Dodger + pink/orange squid on downrigger, Kokanee bug + corn |
| Fall | 5 to 39 ft | dawn | Deep basin (39 ft) | Dodger + squid (deeper red/purple), Small spoon |
| Winter | 10 to 39 ft | dawn | Deep basin (39 ft) | Small glow jig + corn or maggot, Tiny spoon |
Spring puts brook trout in skinny water — 2 to 15 ft is the zone. Warm water sends them out to 10 to 30 ft; cold water stacks them in 3 to 20 ft. Main-lake point is the standout, a point at roughly 7 ft, rated prime for spring brook trout. Plan around early morning and the evening in the warm months. A small spoon fished deep or a trolled lake-clear wobbler + worm covers the summer program.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 2 to 15 ft | dawn & dusk | Main-lake point (7 ft) | Small inline spinner (gold), Tiny spoon |
| Summer | 10 to 30 ft | dawn & dusk | Break off the point (33 ft) | Small spoon fished deep, Trolled lake-clear wobbler + worm |
| Fall | 2 to 15 ft | midday & dawn | Main-lake point (7 ft) | Small spoon (orange), Spinner |
| Winter | 3 to 20 ft | dawn | Shallow bay flat (5 ft) | Small jigging spoon, Tungsten jig + plastic |
Spring lake whitefish on Ackley Lake hold shallow, usually 12 to 39 ft. Depth-wise the year is flat: 12 to 39 ft in summer, 12 to 39 ft once it turns cold. The chart's best answer is Deep basin — deep basin, 39 ft, prime for summer. Prime time lands in early morning. The summer box starts with a blade bait vertical or a small jigging spoon.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 12 to 39 ft | midday & dawn | Break off the point (33 ft) | Small jig + waxworm, Blade bait (small) |
| Summer | 12 to 39 ft | dawn | Deep basin (39 ft) | Blade bait vertical, Small jigging spoon |
| Fall | 8 to 30 ft | dusk | Secondary point (8 ft) | Small spoon (gold), Jig + plastic larva |
| Winter | 12 to 39 ft | midday & dawn | Deep basin (39 ft) | Jigging spoon + bead chain, Tungsten jig + waxie |
When the water first warms, brown trout slide up into 3 to 25 ft. Summer is a 12 to 39 ft game here, winter a 5 to 35 ft one. Start at Break off the point. It's a drop-off holding about 33 ft of water and rates prime come summer. The feeding windows run after dark and early morning. Keep a spoon at the thermocline or a deep stickbait (night) rigged through the warm months.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 3 to 25 ft | dawn & dusk | Main-lake point (7 ft) | Stickbait off planer boards (shallow), Small spoon along mud lines |
| Summer | 12 to 39 ft | night & dawn | Break off the point (33 ft) | Spoon at the thermocline, Deep stickbait (night) |
| Fall | 5 to 30 ft | dusk & dawn | Main-lake point (7 ft) | Jerkbait over gravel, Casting spoon |
| Winter | 5 to 35 ft | dawn | Break off the point (33 ft) | Jigging spoon, Small stickbait (slow) |
Spring puts muskellunge in skinny water — 3 to 12 ft is the zone. As the season builds they drop to 8 to 25 ft, wintering in 15 to 35 ft. Summer muskellunge concentrate at Secondary point, a prime-rated point around 8 ft. Warm-month bites cluster around the evening and early morning. A double-10 bucktail or a topwater (walk-the-dog / creeper) covers the summer program.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 3 to 12 ft | dusk | Shallow bay flat (5 ft) | Smaller bucktail (#8 blades), 6" glide bait |
| Summer | 8 to 25 ft | dusk & dawn | Secondary point (8 ft) | Double-10 bucktail, Topwater (walk-the-dog / creeper) |
| Fall | 8 to 30 ft | midday & dusk | Secondary point (8 ft) | Big rubber (Bull Dawg style), 10"+ glide bait |
| Winter | 15 to 35 ft | midday | Break off the point (33 ft) | Large rubber, crawled slow |
7 pieces of structure are mapped here — Deep basin, around 39 ft, is the deepest of them.
Season dates, license requirements, and size and bag limits for Montana waters are set by the Montana Fish, Wildlife & Parks — and special regulations can apply to Ackley Lake specifically, so confirm the current rules before you fish.
Check the official Montana fishing regulations →
Ackley Lake is about 39 ft (12 m) deep at its deepest point. The depth chart here comes from real state fisheries GPS surveys, so the contours reflect measured depths.
Anglers target rainbow trout, kokanee, brook trout, lake whitefish, brown trout, muskellunge on Ackley Lake.
Deep basin is the top-rated area: a deep basin in about 39 ft of water that rates prime for kokanee in summer. The map above holds the full rated-spot list for every species and season.
For rainbow trout, the summer bite is best in early morning and the evening. Each species page section below lists the seasonal windows, and the map shows a live NOW badge when you're inside one.
Fishing on Ackley Lake is regulated by the Montana Fish, Wildlife & Parks. Check the official Montana regulations for current license requirements, season dates, and size and bag limits — special regulations can apply to this specific water.
Crystal Lake (Fergus) 23 mi · Kolar Reservoir 2 34 mi · Lake Sutherlin 44 mi · Newlan Reservoir 51 mi · Big Wall Pond 77 mi · Wadsworth Lake 78 mi · Gollaher Reservoir 81 mi · Hound Creek Reservoir 83 mi · Yellowstone River 84 mi · Canyon Ferry Reservoir 85 mi · Lewis Pond South 89 mi · Missouri River 90 mi
See how Ackley Lake stacks up: best rainbow trout lakes in Montana · best muskellunge lakes in Montana · best brown trout lakes in Montana · best brook trout lakes in Montana
Browse all Montana fishing maps or see every water on DepthScout. Bathymetry credit: state fisheries survey programs. 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.