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12-acre lake in Mineral County, Montana. The lake tops out around 70 ft. The depth chart comes from published agency bathymetric survey data, so the contours are survey-derived rather than computer-modeled. Below is the species-by-species picture, pulled from the same data the map uses.
Drawn out, this is 12 acres of water rimmed by 0.5 miles of bank. At index 1 the outline is almost a bowl — read the depth changes, not the shoreline. The shallow band under 15 ft claims about 7% of the surface — that's where the groceries are. You'll find it in Mineral County. The nearest mapped water is Pearl Lake, 1 mi to the northwest.
When the water first warms, walleye slide up into 4 to 15 ft. By summer they slide out to 15 to 35 ft, and by winter most fish are in 20 to 40 ft. If you only fish one area, make it Shallow bay flat: a feeding flat around 21 ft that scores good in summer. In summer the feeding windows fall in the evening and early morning. Keep a crawler harness on bottom bouncer or a deep crankbait (trolled) rigged through the warm months.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 4 to 15 ft | dusk & dawn | open water | 1/8 oz jig + minnow, Hair jig |
| Summer | 15 to 35 ft | dusk & dawn | Shallow bay flat (21 ft) | Crawler harness on bottom bouncer, Deep crankbait (trolled) |
| Fall | 12 to 40 ft | dusk & night | open water | Jigging rap, Jig + big minnow |
| Winter | 20 to 40 ft | dusk & dawn | open water | Jigging spoon + minnow head, Rattle bait |
The spring pattern is a shallow one: northern pike in 2 to 8 ft. Midsummer fish sit out in 8 to 20 ft before dropping to 5 to 15 ft for winter. The spot to know is Shallow bay flat, a feeding flat in about 21 ft of water that rates prime for northern pike in summer. Plan around early morning and the evening in the warm months. Summer baits: a bucktail or a weedless spoon over cabbage gets it done.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 2 to 8 ft | midday & dawn | open water | #5 inline spinner, Spoon (red/white) |
| Summer | 8 to 20 ft | dawn & dusk | Shallow bay flat (21 ft) | Bucktail, Weedless spoon over cabbage |
| Fall | 6 to 18 ft | midday & dawn | Shallow bay flat (21 ft) | Big rubber (Bull Dawg style), Husky-style jerkbait |
| Winter | 5 to 15 ft | midday | open water | Tip-ups, Large jigging spoon |
When the water first warms, yellow perch slide up into 3 to 12 ft. Summer is a 10 to 30 ft game here, winter a 15 to 35 ft one. Start at Shallow bay flat. It's a feeding flat holding about 21 ft of water and rates prime come summer. The feeding windows run early morning. Keep a drop-shot micro plastics or a small spoon tipped with worm rigged through the warm months.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 3 to 12 ft | midday & dawn | open water | Small jig + curly tail, Perch-pattern micro crank |
| Summer | 10 to 30 ft | dawn | Shallow bay flat (21 ft) | Drop-shot micro plastics, Small spoon tipped with worm |
| Fall | 12 to 35 ft | midday | open water | Jigging spoon (small), Perch rig / spreader |
| Winter | 15 to 35 ft | midday & dawn | Shallow bay flat (21 ft) | Tungsten jig + spikes, Rattle spoon (small) |
The spring pattern is a shallow one: smallmouth bass in 3 to 12 ft. Midsummer fish sit out in 10 to 30 ft before dropping to 20 to 45 ft for winter. The spot to know is Shoreline break, a drop-off in about 57 ft of water that rates good for smallmouth bass in winter. Plan around early morning and the evening in the warm months. Summer baits: a drop shot (goby/minnow) or a ned rig gets it done.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 3 to 12 ft | dawn & dusk | open water | Ned rig, Tube jig |
| Summer | 10 to 30 ft | dawn & dusk | open water | Drop shot (goby/minnow), Ned rig |
| Fall | 8 to 25 ft | midday & dawn | open water | Jerkbait, Blade bait |
| Winter | 20 to 45 ft | midday | Shoreline break (57 ft) | Blade bait, Hair jig |
In spring, rainbow trout run shallow here, mostly 5 to 20 ft. Summer pushes them deeper, 8 to 30 ft, and winter fish settle into 8 to 40 ft. Shallow bay flat is the standout, a feeding flat at roughly 21 ft, rated good for summer rainbow trout. Time it for early morning and the evening. 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 | Shallow bay flat (21 ft) | Inline spinner (silver), Small spoon |
| Summer | 8 to 30 ft | dawn & dusk | Shallow bay flat (21 ft) | Dodger + spoon (deep troll), Flutter spoon |
| Fall | 10 to 35 ft | dawn & dusk | open water | Casting spoon, Jerkbait over shoals |
| Winter | 8 to 40 ft | dawn | open water | Jigging spoon, Tube jig (white) |
In spring, lake trout run shallow here, mostly 10 to 40 ft. Midsummer fish sit out in 21 to 70 ft before dropping to 18 to 70 ft for winter. Summer lake trout concentrate at Deep basin, a prime-rated deep basin around 70 ft. Fish it in early morning and you'll meet the bite. You won't need more than a white tube jig (deep) or a magnum spoon on downrigger most summer days.
Depth note: when a documented seasonal range extends below this chart, the table shows the deepest mapped working water, not a verified holding depth.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 10 to 40 ft | dawn & dusk | open water | Casting spoon over shoals, Jerkbait (shallow) |
| Summer | 21 to 70 ft chart-limited; documented 50 to 120 ft | dawn | Deep basin (70 ft) | White tube jig (deep), Magnum spoon on downrigger |
| Fall | 10 to 50 ft | dusk & dawn | Shoreline break (57 ft) | Heavy casting spoon, Jigging rap over reefs |
| Winter | 18 to 70 ft chart-limited; documented 20 to 80 ft | dawn | Deep basin (70 ft) | White tube jig, Airplane jig |
Trio Lakes also holds crappie (10 to 25 ft in summer), channel catfish (8 to 25 ft in summer), cutthroat trout (10 to 35 ft in summer). Pick any of them on the map above for rated spots and bait picks.
Structure-wise the chart holds 3 features, led in depth by Deep basin at roughly 70 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 Trio Lakes specifically, so confirm the current rules before you fish.
Check the official Montana fishing regulations →
Trio Lakes is about 70 ft (21 m) deep at its deepest point. The depth chart comes from published agency bathymetric survey data, so the contours are survey-derived rather than computer-modeled.
Anglers target walleye, northern pike, yellow perch, smallmouth bass, rainbow trout, lake trout, crappie, channel catfish, cutthroat trout on Trio Lakes. This isn't a survey of the water — none is published for it — but an informed estimate from the species common to the region, narrowed by this water's depth, size and each species' range.
Deep basin is the top-rated area: a deep basin in about 70 ft of water that rates prime for lake trout in summer. The map above holds the full rated-spot list for every species and season.
For walleye, the summer bite is best in the evening and early morning. Each species page section below lists the seasonal windows, and the map shows a live NOW badge when you're inside one.
Fishing on Trio Lakes 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.
Pearl Lake 1 mi · Hidden Lake (Mineral) 2 mi · French Lake 2 mi · Crater Lake 3 mi · Hoodoo Lake 4 mi · Siamese Lake, Upper 6 mi · Siamese Lake, Lower 6 mi · Cedar Log Lake, North 11 mi · Oregon Lake, Middle 11 mi · Surveyor Lake 12 mi · Cedar Log Lake, South 12 mi · Bonanza Lake, Upper 14 mi
See how Trio Lakes stacks up: best smallmouth bass lakes in Montana · best walleye lakes in Montana · best northern pike lakes in Montana · best crappie lakes in Montana
More water nearby: Mineral County fishing maps (19 charts). Browse all Montana fishing maps. See every water on DepthScout. Bathymetry: published agency survey data. 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.