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20-acre lake in Sweet Grass County, 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. Here's the year, species by species, as the scoring engine sees it.
On the chart, Mirror Lake draws 20 acres inside 0.6 miles of shoreline. At index 1 the outline is almost a bowl — read the depth changes, not the shoreline. About 12% of the surface sits shallower than 15 ft — that's the weed-and-bait zone. The water lies in Sweet Grass County. Closest neighbour on DepthScout: Rainbow Lake, Upper (Rainbow #2), 1 mi east of here.
When the water first warms, walleye slide up into 4 to 15 ft. Summer is a 15 to 35 ft game here, winter a 20 to 40 ft one. Start at Shoreline break. It's a drop-off holding about 43 ft of water and rates prime come fall. The feeding windows run 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 (16 ft) | Crawler harness on bottom bouncer, Deep crankbait (trolled) |
| Fall | 12 to 40 ft | dusk & night | Shoreline break (43 ft) | Jigging rap, Jig + big minnow |
| Winter | 20 to 40 ft | dusk & dawn | Shoreline break (43 ft) | Jigging spoon + minnow head, Rattle bait |
The spring pattern is a shallow one: northern pike in 2 to 8 ft. As the season builds they drop to 8 to 20 ft, wintering in 5 to 15 ft. Top water on the chart: Shallow bay flat, a feeding flat in the 16 ft range, prime in summer. Time it for early morning and the evening. 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 | Shallow bay flat (16 ft) | #5 inline spinner, Spoon (red/white) |
| Summer | 8 to 20 ft | dawn & dusk | Shallow bay flat (16 ft) | Bucktail, Weedless spoon over cabbage |
| Fall | 6 to 18 ft | midday & dawn | Shallow bay flat (16 ft) | Big rubber (Bull Dawg style), Husky-style jerkbait |
| Winter | 5 to 15 ft | midday | Shallow bay flat (16 ft) | Tip-ups, Large jigging spoon |
When the water first warms, yellow perch slide up into 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. If you only fish one area, make it Shallow bay flat: a feeding flat around 16 ft that scores prime in summer. In summer the feeding windows fall in 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 | Shallow bay flat (16 ft) | Small jig + curly tail, Perch-pattern micro crank |
| Summer | 10 to 30 ft | dawn | Shallow bay flat (16 ft) | Drop-shot micro plastics, Small spoon tipped with worm |
| Fall | 12 to 35 ft | midday | Shoreline break (43 ft) | Jigging spoon (small), Perch rig / spreader |
| Winter | 15 to 35 ft | midday & dawn | Shallow bay flat (16 ft) | Tungsten jig + spikes, Rattle spoon (small) |
The spring pattern is a shallow one: smallmouth bass in 3 to 12 ft. As the season builds they drop to 10 to 30 ft, wintering in 20 to 45 ft. Top water on the chart: Shoreline break, a drop-off in the 43 ft range, prime in winter. Time it for early morning and the evening. 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 | Shoreline break (43 ft) | Drop shot (goby/minnow), Ned rig |
| Fall | 8 to 25 ft | midday & dawn | Shoreline break (43 ft) | Jerkbait, Blade bait |
| Winter | 20 to 45 ft | midday | Shoreline break (43 ft) | Blade bait, Hair jig |
In spring, rainbow trout run shallow here, mostly 5 to 20 ft. Midsummer fish sit out in 8 to 30 ft before dropping to 8 to 40 ft for winter. Winter rainbow trout concentrate at Shoreline break, a prime-rated drop-off around 43 ft. Fish it in early morning and the evening and you'll meet the bite. 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 (16 ft) | Inline spinner (silver), Small spoon |
| Summer | 8 to 30 ft | dawn & dusk | Shallow bay flat (16 ft) | Dodger + spoon (deep troll), Flutter spoon |
| Fall | 10 to 35 ft | dawn & dusk | Shoreline break (43 ft) | Casting spoon, Jerkbait over shoals |
| Winter | 8 to 40 ft | dawn | Shoreline break (43 ft) | Jigging spoon, Tube jig (white) |
In spring, lake trout run shallow here, mostly 10 to 40 ft. Summer pushes them deeper, 24 to 80 ft, and winter fish settle into 20 to 80 ft. Deep basin is the standout, a deep basin at roughly 80 ft, rated prime for summer lake trout. Time it for early morning. You won't need more than a white tube jig (deep) or a magnum spoon on downrigger most summer days.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 10 to 40 ft | dawn & dusk | Shoreline break (43 ft) | Casting spoon over shoals, Jerkbait (shallow) |
| Summer | 24 to 80 ft | dawn | Deep basin (80 ft) | White tube jig (deep), Magnum spoon on downrigger |
| Fall | 10 to 50 ft | dusk & dawn | Shoreline break (43 ft) | Heavy casting spoon, Jigging rap over reefs |
| Winter | 20 to 80 ft | dawn | Deep basin (80 ft) | White tube jig, Airplane jig |
Mirror Lake also holds crappie (10 to 25 ft in summer), channel catfish (8 to 25 ft in summer). Pick any of them on the map above for rated spots and bait picks.
3 pieces of structure are mapped here — Deep basin, around 80 ft, is the deepest of them.
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 Mirror Lake specifically, so confirm the current rules before you fish.
Check the official Montana fishing regulations →
Mirror Lake is about 80 ft (24 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 walleye, northern pike, yellow perch, smallmouth bass, rainbow trout, lake trout, crappie, channel catfish on Mirror Lake. 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.
Shoreline break is the top-rated area: a drop-off in about 43 ft of water that rates prime for smallmouth bass in winter. 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 Mirror 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.
Rainbow Lake, Upper (Rainbow #2) 1 mi · Narrow Escape Lake 2 mi · Owl Lake (Sweet Grass) 2 mi · Fish Lake (Sweet Grass) 3 mi · Wounded Man Lake 3 mi · Pentad Lake 4 mi · Jordan Lake (Sweet Grass) 5 mi · Lightning Lake 6 mi · Lake Surrender 6 mi · Cimmerian Lake 6 mi · Jasper Lake (Tumble Lake) 7 mi · Sienna Lake 7 mi
See how Mirror Lake 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: Sweet Grass County fishing maps (10 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.