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20-acre lake in Carbon County, Montana. The lake tops out around 45 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. Species by species, here's what the data says the year looks like.
The outline encloses 20 acres, worked by 0.9 miles of shoreline. A middling shoreline index (1.5) gives it some bays to work without being a maze. About 45% of the surface sits shallower than 15 ft — that's the weed-and-bait zone. Figure 0.4 mi of water from one end to the other, 0.2 mi at the beam. Carbon County claims this one. If the bite dies, Erratic Lake (Carbon) is 1 mi to the northwest.
Come spring, look for brook trout tight to the bank in 2 to 15 ft. They move out to 10 to 30 ft in summer and finish the year down in 3 to 20 ft. If you only fish one area, make it Break off the point: a drop-off around 30 ft that scores prime in summer. Best bite is early morning and the evening. A small spoon fished deep or a trolled lake-clear wobbler + worm is the honest summer answer here.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 2 to 15 ft | dawn & dusk | Main-lake point (11 ft) | Small inline spinner (gold), Tiny spoon |
| Summer | 10 to 30 ft | dawn & dusk | Break off the point (30 ft) | Small spoon fished deep, Trolled lake-clear wobbler + worm |
| Fall | 2 to 15 ft | midday & dawn | Main-lake point (11 ft) | Small spoon (orange), Spinner |
| Winter | 3 to 20 ft | dawn | Shallow bay flat (6 ft) | Small jigging spoon, Tungsten jig + plastic |
The chart marks 4 structure features on Castle Lake; the deepest is Deep basin at about 45 ft.
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 Castle Lake specifically, so confirm the current rules before you fish.
Check the official Montana fishing regulations →
Castle Lake is about 45 ft (14 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 brook trout on Castle Lake.
Break off the point is the top-rated area: a drop-off in about 30 ft of water that rates prime for brook trout in summer. Open the map above to see every rated spot for each species and season.
For brook 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 Castle 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.
Erratic Lake (Carbon) 1 mi · Crystal Lake (Carbon) 1 mi · Green Lake (Carbon) 1 mi · Till Lake 1 mi · Flat Rock Lake 1 mi · Lake Elaine (Carbon) 2 mi · Estelle Lake (Carbon) 2 mi · Donelson Lake 2 mi · Varve Lake (Forsaken Lake) 2 mi · Big Butte Lake 2 mi · Cloverleaf Lake #215 2 mi · Cloverleaf Lake #216 2 mi
See how Castle Lake stacks up: best brook trout lakes in Montana
More water nearby: Carbon County fishing maps (65 charts). 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.