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39-acre lake near Montana. The lake tops out around 80 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. Below is the species-by-species picture, pulled from the same data the map uses.
Start shallow in spring: rainbow trout sit in 5 to 20 ft that time of year. By summer they slide out to 8 to 30 ft, and by winter most fish are in 8 to 40 ft. Main-lake point is the standout, a point at roughly 16 ft, rated prime for spring rainbow trout. Best bite is early morning and the evening. Tie on a dodger + spoon (deep troll) or a flutter spoon and you're in the game.
| Season | Depth | Best window | Go-to baits |
|---|---|---|---|
| Spring | 5 to 20 ft | dawn & dusk | Inline spinner (silver), Small spoon |
| Summer | 8 to 30 ft | dawn & dusk | Dodger + spoon (deep troll), Flutter spoon |
| Fall | 10 to 35 ft | dawn & dusk | Casting spoon, Jerkbait over shoals |
| Winter | 8 to 40 ft | dawn | Jigging spoon, Tube jig (white) |
Spring yellow perch on Dewey Lake hold shallow, usually 3 to 12 ft. By summer they slide out to 10 to 30 ft, and by winter most fish are in 15 to 35 ft. Back-bay flat is the standout, a weed flat at roughly 10 ft, rated prime for spring yellow perch. Plan around early morning in the warm months. A drop-shot micro plastics or a small spoon tipped with worm covers the summer program.
| Season | Depth | Best window | Go-to baits |
|---|---|---|---|
| Spring | 3 to 12 ft | midday & dawn | Small jig + curly tail, Perch-pattern micro crank |
| Summer | 10 to 30 ft | dawn | Drop-shot micro plastics, Small spoon tipped with worm |
| Fall | 12 to 35 ft | midday | Jigging spoon (small), Perch rig / spreader |
| Winter | 15 to 35 ft | midday & dawn | Tungsten jig + spikes, Rattle spoon (small) |
Start shallow in spring: smallmouth bass sit in 3 to 12 ft that time of year. They move out to 10 to 30 ft in summer and finish the year down in 20 to 45 ft. Main-lake point is the standout, a point at roughly 16 ft, rated prime for fall smallmouth bass. In summer the feeding windows fall in early morning and the evening. Summer baits: a drop shot (goby/minnow) or a ned rig gets it done.
| Season | Depth | Best window | Go-to baits |
|---|---|---|---|
| Spring | 3 to 12 ft | dawn & dusk | Ned rig, Tube jig |
| Summer | 10 to 30 ft | dawn & dusk | Drop shot (goby/minnow), Ned rig |
| Fall | 8 to 25 ft | midday & dawn | Jerkbait, Blade bait |
| Winter | 20 to 45 ft | midday | Blade bait, Hair jig |
How deep is Dewey Lake?
Dewey Lake is about 80 ft at its deepest point. The depth chart here comes from real state fisheries GPS surveys, so the contours reflect measured depths.
What fish are in Dewey Lake?
Anglers target smallmouth bass, rainbow trout, yellow perch on Dewey Lake.
Where is the best fishing spot on Dewey Lake?
Back-bay flat is the top-rated area: a weed flat in about 10 ft of water that rates prime for yellow perch in spring. Open the map above to see every rated spot for each species and season.
When is the best time to fish Dewey Lake?
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.
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See how Dewey Lake stacks up: best smallmouth bass lakes in Montana · best rainbow trout lakes in Montana · best yellow perch lakes in Montana
Browse all Montana fishing maps or every water on DepthScout. Bathymetry credit: state fisheries survey programs. How we build these maps. For fishing guidance only, never navigation.