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Fishing Rock Island Lake: what the data says
219-acre lake near Montana. The lake tops out around 100 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. What follows comes from the same scoring engine that paints the spots above.
Cutthroat Trout fishing at Rock Island Lake
In spring, cutthroat trout run shallow here, mostly 3 to 15 ft. They move out to 10 to 35 ft in summer and finish the year down in 10 to 40 ft. Main-lake point is the standout, a point at roughly 25 ft, rated prime for fall cutthroat trout. In summer the feeding windows fall in early morning and the evening. Tie on a trolled spoon (small) or a inline spinner and you're in the game.
| Season | Depth | Best window | Go-to baits |
|---|---|---|---|
| Spring | 3 to 15 ft | dawn & dusk | Inline spinner (silver/gold), Small spoon |
| Summer | 10 to 35 ft | dawn & dusk | Trolled spoon (small), Inline spinner |
| Fall | 5 to 25 ft | dawn & dusk | Casting spoon, Inline spinner |
| Winter | 10 to 40 ft | dawn | Small jigging spoon, Marabou jig |
Brook Trout fishing at Rock Island Lake
In spring, brook trout run shallow here, mostly 2 to 15 ft. Summer pushes them deeper, 10 to 30 ft, and winter fish settle into 3 to 20 ft. Shallow bay flat is the standout, a weed flat at roughly 10 ft, rated good for spring brook trout. Best bite is early morning and the evening. Tie on a small spoon fished deep or a trolled lake-clear wobbler + worm and you're in the game.
| Season | Depth | Best window | Go-to baits |
|---|---|---|---|
| Spring | 2 to 15 ft | dawn & dusk | Small inline spinner (gold), Tiny spoon |
| Summer | 10 to 30 ft | dawn & dusk | Small spoon fished deep, Trolled lake-clear wobbler + worm |
| Fall | 2 to 15 ft | midday & dawn | Small spoon (orange), Spinner |
| Winter | 3 to 20 ft | dawn | Small jigging spoon, Tungsten jig + plastic |
Notable structure
- Deep basin: deep basin, around 100 ft
- Break off the point: drop-off, around 99 ft
- Secondary point: point, around 27 ft
- Main-lake point: point, around 25 ft
- Back-bay flat: weed flat, around 15 ft
- Shallow bay flat: weed flat, around 10 ft
Common questions
How deep is Rock Island Lake?
Rock Island Lake is about 100 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 Rock Island Lake?
Anglers target brook trout, cutthroat trout on Rock Island Lake.
Where is the best fishing spot on Rock Island Lake?
Main-lake point is the top-rated area: a point in about 25 ft of water that rates prime for cutthroat trout in fall. Open the map above to see every rated spot for each species and season.
When is the best time to fish Rock Island Lake?
For cutthroat 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.
Nearby waters
Fox Lake (Park) · Vernon Lake · Widewater Lake (Carbon) · Diamond Lake (Carbon) · Aquarius Lake · Big Moose Lake
See how Rock Island Lake stacks up: best brook trout lakes in Montana · best cutthroat trout 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.