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1,405-acre lake in Timiskaming District, Ontario. The lake tops out around 90 ft. The contours come from a model of the real basin shape and its known max depth. Read them as probabilities, not soundings, and keep them out of navigation decisions. Species by species, here's what the data says the year looks like.
Drawn out, this is 1,408 acres of water rimmed by 14.9 miles of bank. The 2.8 development index tells the story — a convoluted bank whose fishable edge far outruns the acreage. Roughly 47% of the water is 15 ft or less as modeled, the band where the food chain lives. Call it 2.7 mi long by 1.8 mi wide at the broadest reach. You'll find it in Timiskaming District. For a second option, Brewster L. 41 lies 2 mi west.
In spring, lake trout run shallow here, mostly 10 to 40 ft. Midsummer fish sit out in 27 to 90 ft before dropping to 20 to 80 ft for winter. Summer lake trout concentrate at Deep basin, a prime-rated deep basin around 77 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.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 10 to 40 ft | dawn & dusk | Main-lake point (23 ft) | Casting spoon over shoals, Jerkbait (shallow) |
| Summer | 27 to 90 ft | dawn | Deep basin (77 ft) | White tube jig (deep), Magnum spoon on downrigger |
| Fall | 10 to 50 ft | dusk & dawn | Main-lake point (23 ft) | Heavy casting spoon, Jigging rap over reefs |
| Winter | 20 to 80 ft | dawn | Deep basin (77 ft) | White tube jig, Airplane jig |
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 weed flat holding about 6 ft of water and rates prime come spring. 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 | Shallow bay flat (6 ft) | Small jig + curly tail, Perch-pattern micro crank |
| Summer | 10 to 30 ft | dawn | Shallow bay flat (6 ft) | Drop-shot micro plastics, Small spoon tipped with worm |
| Fall | 12 to 35 ft | midday | Break off the point (41 ft) | Jigging spoon (small), Perch rig / spreader |
| Winter | 15 to 35 ft | midday & dawn | Deep basin (77 ft) | Tungsten jig + spikes, Rattle spoon (small) |
In spring, burbot run shallow here, mostly 25 to 70 ft. Midsummer fish sit out in 27 to 90 ft before dropping to 15 to 60 ft for winter. Summer burbot concentrate at Deep basin, a prime-rated deep basin around 77 ft. Fish it in after dark and midday and you'll meet the bite. You won't need more than a heavy jig + cut bait most summer days.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 25 to 70 ft | night & dusk | Deep basin (77 ft) | Glow jigging spoon + cut bait, Rattle bait (dark) |
| Summer | 27 to 90 ft | night & midday | Deep basin (77 ft) | Heavy jig + cut bait |
| Fall | 30 to 80 ft | night & dusk | Deep basin (77 ft) | Glow spoon + minnow head, Blade bait (slow) |
| Winter | 15 to 60 ft | night & dusk | Break off the point (41 ft) | Glow tungsten + cut bait, Rattle spoon + minnow head |
6 pieces of structure are mapped here — Deep basin, around 77 ft, is the deepest of them.
Season dates, license requirements, and size and bag limits for Ontario waters are set by the Ontario fishing regulations (FMZ summary) — and special regulations can apply to Trethewey Lake specifically, so confirm the current rules before you fish.
Check the official Ontario fishing regulations →
Trethewey Lake is about 90 ft (27 m) deep at its deepest point. The contours here are modeled from the water's real shape and maximum depth, so treat them as a rough guide.
Anglers target lake trout, yellow perch, burbot on Trethewey Lake.
Deep basin is the top-rated area: a deep basin in about 77 ft of water that rates prime for lake trout in summer. Every other rated spot, per species and season, is on the map above.
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.
Fishing on Trethewey Lake is regulated by the Ontario fishing regulations (FMZ summary). Check the official Ontario regulations for current license requirements, season dates, and size and bag limits — special regulations can apply to this specific water.
Brewster L. 41 2 mi · Kaa Lake 3 mi · Elissa Lake 3 mi · Makobe Lake 3 mi · Gooseneck Lake 4 mi · Gamble Lake 4 mi · Chalice Lake 4 mi · Chance Lake 4 mi · Wabun Lake 5 mi · Carmen Lake 5 mi · Grays Lake 6 mi · Paddle Lake 6 mi
See how Trethewey Lake stacks up: best yellow perch lakes in Ontario · best lake trout lakes in Ontario · best burbot lakes in Ontario
More water nearby: Timiskaming District fishing maps (515 charts). Browse all Ontario fishing maps or see every water on DepthScout. 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.