Flathead 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.

Loading depth chart…

Recent catches at Flathead 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 Flathead Lake on the board.

Fishing Flathead Lake: what the data says

122,000-acre reservoir near Polson. The lake tops out around 380 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. Below is the species-by-species picture, pulled from the same data the map uses.

Drawn out, this is 122,938 acres of water rimmed by 181.1 miles of bank — 26 islands included. With a shoreline index of 3.7, this water is all arms and coves — edge habitat well beyond its acreage. 7% of the surface is littoral (under ~15 ft) — cover, weeds and forage water. Figure 29.1 mi of water from one end to the other, 15.5 mi at the beam. You'll find it in Lake County. For a second option, Jette Lake lies 9 mi south.

Lake Trout fishing at Flathead Lake

Start shallow in spring: lake trout sit in 10 to 40 ft that time of year. Warm water sends them out to 50 to 120 ft; cold water stacks them in 20 to 80 ft. Top water on the chart: Rock reef, a rock pile in the 43 ft range, prime in fall. Fish it in early morning and you'll meet the bite. Throw a white tube jig (deep) or a magnum spoon on downrigger until the fish tell you otherwise.

Season	Depth	Best window	Start at	Go-to baits
Spring	10 to 40 ft	dawn & dusk	Main-lake point (17 ft)	Casting spoon over shoals, Jerkbait (shallow)
Summer	50 to 120 ft	dawn	Offshore hump (89 ft)	White tube jig (deep), Magnum spoon on downrigger
Fall	10 to 50 ft	dusk & dawn	Rock reef (43 ft)	Heavy casting spoon, Jigging rap over reefs
Winter	20 to 80 ft	dawn	Offshore hump (50 ft)	White tube jig, Airplane jig

Lake Whitefish fishing at Flathead Lake

When the water first warms, lake whitefish slide up into 15 to 45 ft. Summer is a 40 to 90 ft game here, winter a 25 to 70 ft one. Start at Rock reef. It's a rock pile holding about 43 ft of water and rates prime come spring. The feeding windows run early morning. Keep a blade bait vertical or a small jigging spoon rigged through the warm months.

Season	Depth	Best window	Start at	Go-to baits
Spring	15 to 45 ft	midday & dawn	Rock reef (43 ft)	Small jig + waxworm, Blade bait (small)
Summer	40 to 90 ft	dawn	Offshore hump (89 ft)	Blade bait vertical, Small jigging spoon
Fall	8 to 30 ft	dusk	Offshore hump (27 ft)	Small spoon (gold), Jig + plastic larva
Winter	25 to 70 ft	midday & dawn	Offshore hump (50 ft)	Jigging spoon + bead chain, Tungsten jig + waxie

Yellow Perch fishing at Flathead Lake

Spring yellow perch on Flathead Lake hold shallow, usually 3 to 12 ft. They move out to 10 to 30 ft in summer and finish the year down in 15 to 35 ft. Put Feeding flat first on the milk run — a feeding flat near 6 ft that grades prime for spring. The feeding windows run early morning. The summer box starts with a drop-shot micro plastics or a small spoon tipped with worm.

Season	Depth	Best window	Start at	Go-to baits
Spring	3 to 12 ft	midday & dawn	Feeding flat (6 ft)	Small jig + curly tail, Perch-pattern micro crank
Summer	10 to 30 ft	dawn	Offshore hump (27 ft)	Drop-shot micro plastics, Small spoon tipped with worm
Fall	12 to 35 ft	midday	Offshore hump (27 ft)	Jigging spoon (small), Perch rig / spreader
Winter	15 to 35 ft	midday & dawn	Offshore hump (27 ft)	Tungsten jig + spikes, Rattle spoon (small)

Bull Trout fishing at Flathead Lake

The spring pattern is a shallow one: bull trout in 10 to 40 ft. Midsummer fish sit out in 30 to 90 ft before dropping to 20 to 70 ft for winter. The spot to know is Sharp break, a drop-off in about 44 ft of water that rates prime for bull trout in winter. Plan around early morning and the evening in the warm months. Summer baits: a trolled plug on downrigger or a heavy jigging spoon gets it done.

Season	Depth	Best window	Start at	Go-to baits
Spring	10 to 40 ft	dawn & dusk	Main-lake point (17 ft)	Large jointed plug, 6" swimbait (kokanee/trout pattern)
Summer	30 to 90 ft	dawn & dusk	Sharp break (71 ft)	Trolled plug on downrigger, Heavy jigging spoon
Fall	5 to 35 ft	dawn & dusk	Main-lake point (17 ft)	Large glide bait, Jointed plug
Winter	20 to 70 ft	dawn	Sharp break (44 ft)	Heavy spoon (slow lift), Large soft swimbait

Cutthroat Trout fishing at Flathead Lake

Early season cutthroat trout use the shallows, holding in 3 to 15 ft. Expect a summer slide to 10 to 35 ft, then a winter hold in 10 to 40 ft. Put Main-lake point first on the milk run — a point near 17 ft that grades prime for fall. In summer the feeding windows fall in early morning and the evening. Tie on a trolled spoon (small) or an inline spinner and you're in the game.

Season	Depth	Best window	Start at	Go-to baits
Spring	3 to 15 ft	dawn & dusk	Shoreline point (4 ft)	Inline spinner (silver/gold), Small spoon
Summer	10 to 35 ft	dawn & dusk	Main-lake point (17 ft)	Trolled spoon (small), Inline spinner
Fall	5 to 25 ft	dawn & dusk	Main-lake point (17 ft)	Casting spoon, Inline spinner
Winter	10 to 40 ft	dawn	Sharp break (44 ft)	Small jigging spoon, Marabou jig

Northern Pike fishing at Flathead Lake

Spring puts northern pike in skinny water — 2 to 8 ft is the zone. Warm water sends them out to 8 to 20 ft; cold water stacks them in 5 to 15 ft. Feeding flat is the standout, a feeding flat at roughly 6 ft, rated prime for spring northern pike. Plan around early morning and the evening in the warm months. A bucktail or a weedless spoon over cabbage covers the summer program.

Season	Depth	Best window	Start at	Go-to baits
Spring	2 to 8 ft	midday & dawn	Feeding flat (6 ft)	#5 inline spinner, Spoon (red/white)
Summer	8 to 20 ft	dawn & dusk	Shallow bay flat (14 ft)	Bucktail, Weedless spoon over cabbage
Fall	6 to 18 ft	midday & dawn	Main-lake point (17 ft)	Big rubber (Bull Dawg style), Husky-style jerkbait
Winter	5 to 15 ft	midday	Shallow bay flat (14 ft)	Tip-ups, Large jigging spoon

Notable structure

Structure-wise the chart holds 52 features, led in depth by Deep basin at roughly 370 ft.

Deep basin: deep basin, around 370 ft
Deepest basin: deep basin, around 219 ft
Deep break: drop-off, around 200 ft
Deep break: drop-off, around 167 ft
Sharp break: drop-off, around 137 ft
Break off the point: drop-off, around 135 ft
Feeding flat: feeding flat, around 101 ft
Deep break: drop-off, around 98 ft
Sharp break: drop-off, around 96 ft
Sharp break: drop-off, around 94 ft
Offshore hump: offshore hump, around 89 ft
Feeding flat: feeding flat, around 85 ft
Offshore hump: offshore hump, around 71 ft
Sharp break: drop-off, around 71 ft

Public access & boat ramps

Somers — ramp (concrete)
Walstad — ramp (concrete)
Woods Bay — ramp (concrete)
Conclow

Access data: Montana FWP — Fishing Access Sites. Confirm conditions and fees locally before you launch.

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

Check the official Montana fishing regulations →

Common questions

How deep is Flathead Lake?

Flathead Lake is about 380 ft (116 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 Flathead Lake?

Anglers target lake trout, lake whitefish, yellow perch, bull trout, cutthroat trout, northern pike on Flathead Lake.

Where is the best fishing spot on Flathead Lake?

Sharp break is the top-rated area: a drop-off in about 44 ft of water that rates prime for bull trout in winter. Every other rated spot, per species and season, is on the map above.

When is the best time to fish Flathead Lake?

For lake trout, the summer bite is best in 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 Flathead Lake?

Fishing on Flathead 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

Jette Lake 9 mi · Lake Mary Ronan 11 mi · Horseshoe Lake (Lake) 13 mi · Loon Lake (Lake) 13 mi · Swan Lake 14 mi · Mccaffery Lake 17 mi · Fatty Lake 17 mi · Abbot Lake 18 mi · Peterson Lake 18 mi · Echo Lake (Flathead) 18 mi · Half Moon Slough 20 mi · Cabin Lake 20 mi

See how Flathead Lake stacks up: best northern pike lakes in Montana · best yellow perch lakes in Montana · best lake trout lakes in Montana · best lake whitefish lakes in Montana

More water nearby: Lake County fishing maps (12 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.