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171-acre reservoir in Rosebud County, Montana. The lake tops out around 40 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.
The outline encloses 171 acres, worked by 1.9 miles of shoreline. Nearly circular (index 1.1), so the story is the bottom, not the bank. 44% of the surface is littoral (under ~15 ft) — cover, weeds and forage water. Figure 0.7 mi of water from one end to the other, 0.5 mi at the beam. Rosebud County claims this one. Its nearest charted neighbour, Spotted Eagle Lake, is 51 mi to the northeast.
Early season crappie use the shallows, holding in 2 to 8 ft. Expect a summer slide to 10 to 25 ft, then a winter hold in 15 to 35 ft. Put Shallow bay flat first on the milk run — a weed flat near 3 ft that grades prime for spring. In summer the feeding windows fall in early morning and the evening. Tie on a jig trolled/spider-rigged or a small crankbait (trolled) and you're in the game.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 2 to 8 ft | midday & dawn | Shallow bay flat (3 ft) | 1/16 oz jig + tube, Curly-tail grub |
| Summer | 10 to 25 ft | dawn & dusk | Break off the point (19 ft) | Jig trolled/spider-rigged, Small crankbait (trolled) |
| Fall | 8 to 20 ft | dawn | Break off the point (19 ft) | Jig + minnow combo, Small swimbait (1.5-2") |
| Winter | 15 to 35 ft | midday | Deep basin (40 ft) | Tungsten jig + soft plastic, Tiny jigging spoon |
The spring pattern is a shallow one: walleye in 4 to 15 ft. As the season builds they drop to 15 to 35 ft, wintering in 20 to 40 ft. Top water on the chart: Break off the point, a drop-off in the 19 ft range, prime in fall. Time it for the evening and early morning. Summer baits: a crawler harness on bottom bouncer or a deep crankbait (trolled) gets it done.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 4 to 15 ft | dusk & dawn | Secondary point (6 ft) | 1/8 oz jig + minnow, Hair jig |
| Summer | 15 to 35 ft | dusk & dawn | Break off the point (19 ft) | Crawler harness on bottom bouncer, Deep crankbait (trolled) |
| Fall | 12 to 40 ft | dusk & night | Break off the point (19 ft) | Jigging rap, Jig + big minnow |
| Winter | 20 to 40 ft | dusk & dawn | Deep basin (40 ft) | Jigging spoon + minnow head, Rattle bait |
Spring channel catfish on Castle Rock Reservoir hold shallow, usually 3 to 12 ft. By summer they slide out to 8 to 25 ft, and by winter most fish are in 20 to 40 ft. The chart's best answer is Deep basin — deep basin, 40 ft, prime for winter. Prime time lands in after dark and the evening.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 3 to 12 ft | dusk | Shallow bay flat (3 ft) | |
| Summer | 8 to 25 ft | night & dusk | Break off the point (19 ft) | |
| Fall | 10 to 30 ft | dusk | Break off the point (19 ft) | |
| Winter | 20 to 40 ft | midday | Deep basin (40 ft) |
Spring largemouth bass on Castle Rock Reservoir hold shallow, usually 2 to 10 ft. By summer they slide out to 8 to 20 ft, and by winter most fish are in 15 to 35 ft. The chart's best answer is Shallow bay flat — weed flat, 3 ft, prime for spring. Prime time lands in early morning and the evening. The summer box starts with a texas-rigged 10" worm or a deep-diving crankbait.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 2 to 10 ft | dawn & dusk | Shallow bay flat (3 ft) | Spinnerbait, Chatterbait |
| Summer | 8 to 20 ft | dawn & dusk | Break off the point (19 ft) | Texas-rigged 10" worm, Deep-diving crankbait |
| Fall | 4 to 15 ft | midday & dawn | Secondary point (6 ft) | Squarebill crankbait (shad), Spinnerbait |
| Winter | 15 to 35 ft | midday | Break off the point (19 ft) | Blade bait, Jigging spoon |
Early season northern pike use the shallows, holding in 2 to 8 ft. Expect a summer slide to 8 to 20 ft, then a winter hold in 5 to 15 ft. Put Shallow bay flat first on the milk run — a weed flat near 3 ft that grades prime for spring. In summer the feeding windows fall in early morning and the evening. Tie on a bucktail or a weedless spoon over cabbage and you're in the game.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 2 to 8 ft | midday & dawn | Shallow bay flat (3 ft) | #5 inline spinner, Spoon (red/white) |
| Summer | 8 to 20 ft | dawn & dusk | Break off the point (19 ft) | Bucktail, Weedless spoon over cabbage |
| Fall | 6 to 18 ft | midday & dawn | Break off the point (19 ft) | Big rubber (Bull Dawg style), Husky-style jerkbait |
| Winter | 5 to 15 ft | midday | Shallow bay flat (3 ft) | Tip-ups, Large jigging spoon |
In spring, pumpkinseed run shallow here, mostly 1 to 8 ft. Midsummer fish sit out in 2 to 10 ft before dropping to 6 to 18 ft for winter. Spring pumpkinseed concentrate at Shallow bay flat, a prime-rated weed flat around 3 ft. Fish it in the evening and early morning and you'll meet the bite. You won't need more than a micro tube or a sponge spider (fly) most summer days.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 1 to 8 ft | midday & dusk | Shallow bay flat (3 ft) | Micro jig under a float, Tiny beetle-spin |
| Summer | 2 to 10 ft | dusk & dawn | Shallow bay flat (3 ft) | Micro tube, Sponge spider (fly) |
| Fall | 4 to 14 ft | dusk & dawn | Shallow bay flat (3 ft) | Micro jig + waxworm, Small spoon tipped |
| Winter | 6 to 18 ft | dawn | Shallow bay flat (3 ft) | Tungsten ice jig + plastic, Tiny spoon |
Castle Rock Reservoir also holds smallmouth bass (10 to 30 ft in summer), bluegill (4 to 15 ft in summer). Pick any of them on the map above for rated spots and bait picks.
Structure-wise the chart holds 6 features, led in depth by Deep basin at roughly 40 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 Rock Reservoir specifically, so confirm the current rules before you fish.
Check the official Montana fishing regulations →
Castle Rock Reservoir is about 40 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 crappie, walleye, channel catfish, largemouth bass, northern pike, pumpkinseed, smallmouth bass, bluegill on Castle Rock Reservoir.
Break off the point is the top-rated area: a drop-off in about 19 ft of water that rates prime for walleye in fall. Open the map above to see every rated spot for each species and season.
For crappie, 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 Rock Reservoir 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.
Spotted Eagle Lake 51 mi · Bighorn River 62 mi · Kleenburn Pond 2 71 mi, WY · Yellowtail Afterbay Reservoir 74 mi · Lake Elmo 88 mi · Bighorn Lake 91 mi, MT/WY · Lake Josephine 91 mi · Joels Pond 95 mi · Big Stull Lake 96 mi, WY · Dream Lake 96 mi, WY · Coney Lake 97 mi, WY · Big Wall Pond 97 mi
See how Castle Rock Reservoir stacks up: best largemouth bass lakes in Montana · best smallmouth bass lakes in Montana · best walleye lakes in Montana · best northern pike 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.