Big Lake Depth Map & Fishing Spots (MT)

Hatch outlook

Grasshoppers (east-side summer)Active window

Typical here: Jul 1 – Oct 15 · until the hard frosts of mid-October; on the Missouri, August hoppers fish mid-river, not the banks

adultall day in high summer, best when afternoon wind knocks bugs onto the water

Pulls fish to the windward grassy banks and edges for months — fish the bank the wind blows ONTO.

The friendliest crossover of the summer: on lakes, drift the windward bank with a bubble-and-foam-hopper — the bubble's splash doesn't hurt a hopper presentation. On rivers, the same rig dead-drifted along the undercut grass banks, or small gold spinners under the banks between rises.

The event happens over grassy banks, undercut edges and windward shorelines

Spruce MothActive window

Typical here: Jul 20 – Aug 31 · a conifer-forest event — it needs fir and lodgepole on the banks, so it's a Rock Creek / Blackfoot / upper Bitterroot specialty

adultmorning through midday — moths don't enter the water willingly — landings are sporadic and near the conifer banks; fish the imitation LOW in the film with minimal floatant, even fully drowned, with a little movement

When the moths show, just about every run produces — large trout key on them so hard that one pattern carries the whole box for two weeks.

Honest limit: a small drowned-surface moth has no lure analog. The workable rig is a casting bubble with a drowned moth pattern along the timbered banks in the morning; otherwise fish spinners early and late and leave the moth window to the film.

2–3 weeks at best, and day-to-day — fish key on the moths when they show and vanish with them

The event happens over banks under conifers — the moths rarely reach mid-river

Recommendations come from depth structure and seasonal species behavior. Treat them as a starting point, not a guarantee. Contours here are interpolated from real agency depth surveys (state DNR / USACE). Never use for navigation. Always check local regulations.

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Recent catches at Big Lake

Shared by DepthScout anglers. Exact spots stay private, always.

No shared catches here yet — be the first.Log a catch from the map above and share it to put Big Lake on the board.

Fishing Big Lake: what the data says

34-acre lake in Missoula County, Montana. The lake tops out around 130 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 the data behind the map says about each species, season by season:

The outline encloses 38 acres, worked by 0.9 miles of shoreline. The basin is a simple one (shoreline index 1.1) — close to a bowl, so the structure on the chart matters more than the bank. The shallow band under 15 ft claims about 8% of the surface — that's where the groceries are. Figure 0.3 mi of water from one end to the other, 0.3 mi at the beam. Missoula County claims this one. Its nearest charted neighbour, Sheridan Lake, is 0 mi to the east.

Walleye fishing at Big Lake

In spring, walleye run shallow here, mostly 4 to 15 ft. Summer pushes them deeper, 15 to 35 ft, and winter fish settle into 20 to 40 ft. Back-bay flat is the standout, a feeding flat at roughly 15 ft, rated good for summer walleye. Time it for the evening and early morning. You won't need more than a crawler harness on bottom bouncer or a deep crankbait (trolled) most summer days.

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	Back-bay flat (15 ft)	Crawler harness on bottom bouncer, Deep crankbait (trolled)
Fall	12 to 40 ft	dusk & night	Shoreline break (87 ft)	Jigging rap, Jig + big minnow
Winter	20 to 40 ft	dusk & dawn	Deep basin (129 ft)	Jigging spoon + minnow head, Rattle bait

Northern Pike fishing at Big Lake

When the water first warms, northern pike slide up into 2 to 8 ft. By summer they slide out to 8 to 20 ft, and by winter most fish are in 5 to 15 ft. If you only fish one area, make it Shallow bay flat: a feeding flat around 10 ft that scores prime in winter. In summer the feeding windows fall in early morning and the evening. Keep a bucktail or a weedless spoon over cabbage rigged through the warm months.

Season	Depth	Best window	Start at	Go-to baits
Spring	2 to 8 ft	midday & dawn	Shallow bay flat (10 ft)	#5 inline spinner, Spoon (red/white)
Summer	8 to 20 ft	dawn & dusk	Shallow bay flat (10 ft)	Bucktail, Weedless spoon over cabbage
Fall	6 to 18 ft	midday & dawn	Shallow bay flat (10 ft)	Big rubber (Bull Dawg style), Husky-style jerkbait
Winter	5 to 15 ft	midday	Shallow bay flat (10 ft)	Tip-ups, Large jigging spoon

Yellow Perch fishing at Big Lake

The spring pattern is a shallow one: yellow perch in 3 to 12 ft. As the season builds they drop to 10 to 30 ft, wintering in 15 to 35 ft. Top water on the chart: Shallow bay flat, a feeding flat in the 10 ft range, prime in spring. Time it for early morning. Summer baits: a drop-shot micro plastics or a small spoon tipped with worm gets it done.

Season	Depth	Best window	Start at	Go-to baits
Spring	3 to 12 ft	midday & dawn	Shallow bay flat (10 ft)	Small jig + curly tail, Perch-pattern micro crank
Summer	10 to 30 ft	dawn	Shallow bay flat (10 ft)	Drop-shot micro plastics, Small spoon tipped with worm
Fall	12 to 35 ft	midday	Deep basin (129 ft)	Jigging spoon (small), Perch rig / spreader
Winter	15 to 35 ft	midday & dawn	Back-bay flat (15 ft)	Tungsten jig + spikes, Rattle spoon (small)

Smallmouth Bass fishing at Big Lake

When the water first warms, smallmouth bass slide up into 3 to 12 ft. By summer they slide out to 10 to 30 ft, and by winter most fish are in 20 to 45 ft. If you only fish one area, make it Shoreline break: a drop-off around 87 ft that scores good in winter. In summer the feeding windows fall in early morning and the evening. Keep a drop shot (goby/minnow) or a ned rig rigged through the warm months.

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 (87 ft)	Drop shot (goby/minnow), Ned rig
Fall	8 to 25 ft	midday & dawn	Shoreline break (87 ft)	Jerkbait, Blade bait
Winter	20 to 45 ft	midday	Shoreline break (87 ft)	Blade bait, Hair jig

Rainbow Trout fishing at Big Lake

Spring rainbow trout on Big Lake hold shallow, usually 5 to 20 ft. They move out to 8 to 30 ft in summer and finish the year down in 8 to 40 ft. Put Shallow bay flat first on the milk run — a feeding flat near 10 ft that grades good for spring. The feeding windows run early morning and the evening. The summer box starts with a dodger + spoon (deep troll) or a flutter spoon.

Season	Depth	Best window	Start at	Go-to baits
Spring	5 to 20 ft	dawn & dusk	Shallow bay flat (10 ft)	Inline spinner (silver), Small spoon
Summer	8 to 30 ft	dawn & dusk	Shallow bay flat (10 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	Shoreline break (87 ft)	Jigging spoon, Tube jig (white)

Lake Trout fishing at Big Lake

When the water first warms, lake trout slide up into 10 to 40 ft. Summer is a 50 to 120 ft game here, winter a 20 to 80 ft one. Start at Deep basin. It's a deep basin holding about 129 ft of water and rates prime come summer. The feeding windows run early morning. Keep a white tube jig (deep) or a magnum spoon on downrigger rigged through the warm months.

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	50 to 120 ft	dawn	Deep basin (129 ft)	White tube jig (deep), Magnum spoon on downrigger
Fall	10 to 50 ft	dusk & dawn	open water	Heavy casting spoon, Jigging rap over reefs
Winter	20 to 80 ft	dawn	Shoreline break (87 ft)	White tube jig, Airplane jig

Big 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.

Notable structure

4 pieces of structure are mapped here — Deep basin, around 129 ft, is the deepest of them.

Deep basin: deep basin, around 129 ft
Shoreline break: drop-off, around 87 ft
Back-bay flat: feeding flat, around 15 ft
Shallow bay flat: feeding flat, around 10 ft

Big Lake fishing regulations

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 Big Lake specifically, so confirm the current rules before you fish.

Check the official Montana fishing regulations →

Common questions

How deep is Big Lake?

Big Lake is about 130 ft (40 m) deep 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 Big Lake?

Anglers target walleye, northern pike, yellow perch, smallmouth bass, rainbow trout, lake trout, crappie, channel catfish on Big 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.

Where is the best fishing spot on Big Lake?

Deep basin is the top-rated area: a deep basin in about 129 ft of water that rates prime for lake trout in summer. Scroll up to the map for the complete spot list by species and season.

When is the best time to fish Big Lake?

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.

What are the fishing regulations for Big Lake?

Fishing on Big 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.

Nearby waters

Sheridan Lake 0 mi · Little Lake 1 mi · Glacier Lake 1 mi · McKinley Lake 2 mi · Sanders Lake 2 mi · Farmers Lake #6 2 mi · Farmers Lake #5 3 mi · Rattlesnake Lake #22 4 mi · Boulder Lake 5 mi · Fly Lake (Missoula) 6 mi · St Marys Lake 15 mi · Frenchtown Pond 16 mi

See how Big 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: Missoula County fishing maps (37 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.