Thompson Lake, Upper 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 Thompson Lake, Upper

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 Thompson Lake, Upper on the board.

Fishing Thompson Lake, Upper: what the data says

415-acre lake in Lincoln County, Montana. The lake tops out around 100 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. The season-by-season read for each species follows, from the map's own numbers.

Walleye fishing at Thompson Lake, Upper

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 Break off the point. It's a drop-off holding about 20 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	Main-lake point (1 ft)	1/8 oz jig + minnow, Hair jig
Summer	15 to 35 ft	dusk & dawn	Break off the point (20 ft)	Crawler harness on bottom bouncer, Deep crankbait (trolled)
Fall	12 to 40 ft	dusk & night	Break off the point (20 ft)	Jigging rap, Jig + big minnow
Winter	20 to 40 ft	dusk & dawn	Break off the point (20 ft)	Jigging spoon + minnow head, Rattle bait

Northern Pike fishing at Thompson Lake, Upper

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: Break off the point, a drop-off in the 20 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 (1 ft)	#5 inline spinner, Spoon (red/white)
Summer	8 to 20 ft	dawn & dusk	Break off the point (20 ft)	Bucktail, Weedless spoon over cabbage
Fall	6 to 18 ft	midday & dawn	Break off the point (20 ft)	Big rubber (Bull Dawg style), Husky-style jerkbait
Winter	5 to 15 ft	midday	Shallow bay flat (1 ft)	Tip-ups, Large jigging spoon

Yellow Perch fishing at Thompson Lake, Upper

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 Break off the point: a drop-off around 20 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 (1 ft)	Small jig + curly tail, Perch-pattern micro crank
Summer	10 to 30 ft	dawn	Break off the point (20 ft)	Drop-shot micro plastics, Small spoon tipped with worm
Fall	12 to 35 ft	midday	Break off the point (20 ft)	Jigging spoon (small), Perch rig / spreader
Winter	15 to 35 ft	midday & dawn	Break off the point (20 ft)	Tungsten jig + spikes, Rattle spoon (small)

Smallmouth Bass fishing at Thompson Lake, Upper

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: Break off the point, a drop-off in the 20 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	Main-lake point (1 ft)	Ned rig, Tube jig
Summer	10 to 30 ft	dawn & dusk	Break off the point (20 ft)	Drop shot (goby/minnow), Ned rig
Fall	8 to 25 ft	midday & dawn	Break off the point (20 ft)	Jerkbait, Blade bait
Winter	20 to 45 ft	midday	Break off the point (20 ft)	Blade bait, Hair jig

Rainbow Trout fishing at Thompson Lake, Upper

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 Break off the point, a prime-rated drop-off around 20 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	Break off the point (20 ft)	Inline spinner (silver), Small spoon
Summer	8 to 30 ft	dawn & dusk	Break off the point (20 ft)	Dodger + spoon (deep troll), Flutter spoon
Fall	10 to 35 ft	dawn & dusk	Break off the point (20 ft)	Casting spoon, Jerkbait over shoals
Winter	8 to 40 ft	dawn	Break off the point (20 ft)	Jigging spoon, Tube jig (white)

Lake Trout fishing at Thompson Lake, Upper

In spring, lake trout run shallow here, mostly 10 to 40 ft. Summer pushes them deeper, 30 to 100 ft, and winter fish settle into 20 to 80 ft. Deep basin is the standout, a deep basin at roughly 98 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	Break off the point (20 ft)	Casting spoon over shoals, Jerkbait (shallow)
Summer	30 to 100 ft	dawn	Deep basin (98 ft)	White tube jig (deep), Magnum spoon on downrigger
Fall	10 to 50 ft	dusk & dawn	Break off the point (20 ft)	Heavy casting spoon, Jigging rap over reefs
Winter	20 to 80 ft	dawn	Break off the point (20 ft)	White tube jig, Airplane jig

Thompson Lake, Upper 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

The chart marks 6 structure features on Thompson Lake, Upper; the deepest is Deep basin at about 98 ft.

Deep basin: deep basin, around 98 ft
Break off the point: drop-off, around 20 ft
Main-lake point: point, around 1 ft
Secondary point: point, around 1 ft
Shallow bay flat: feeding flat, around 1 ft
Back-bay flat: feeding flat, around 1 ft

Public access & boat ramps

Boat launch — ramp

Access data: OpenStreetMap contributors (ODbL) — community-mapped launches. Confirm conditions and fees locally before you launch.

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

Check the official Montana fishing regulations →

Common questions

How deep is Thompson Lake, Upper?

Thompson Lake, Upper is about 100 ft (30 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 Thompson Lake, Upper?

Anglers target walleye, northern pike, yellow perch, smallmouth bass, rainbow trout, lake trout, crappie, channel catfish on Thompson Lake, Upper. 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 Thompson Lake, Upper?

Break off the point is the top-rated area: a drop-off in about 20 ft of water that rates prime for walleye in fall. The interactive chart above rates every spot for each species and season.

When is the best time to fish Thompson Lake, Upper?

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 Thompson Lake, Upper?

Fishing on Thompson Lake, Upper 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

Crystal Lake (Lincoln) 2 mi · Thompson Lake, Middle 3 mi · Horseshoe Lake (Lincoln) 3 mi · Leon Lake 3 mi · Little Loon Lake 4 mi · Thompson Lake, Lower 5 mi · Mcgregor Lake 12 mi · Island Lake 15 mi · Little Bitterroot Lake 19 mi · Hubbart Reservoir 20 mi · Rogers Lake 24 mi · Sylvia Lake 24 mi

See how Thompson Lake, Upper 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: Lincoln County fishing maps (28 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.