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686-acre lake in Sudbury District, Ontario. The lake tops out around 120 ft. The depth data here comes from a transect sounding survey by the Ontario MNRF. What the data behind the map says about each species, season by season:
On the chart, O.S.A. Lake draws 689 acres inside 12.3 miles of shoreline — 20 islands included. An index of 3.3 puts the bank firmly in maze territory: point after pocket after cove, every one a casting target. The shallow band under 15 ft claims about 18% of the surface — that's where the groceries are. Call it 2.1 mi long by 1.1 mi wide at the broadest reach. You'll find it in Sudbury District. Closest neighbour on DepthScout: Teardrop Lake, 1 mi southwest of here.
In spring, lake trout run shallow here, mostly 10 to 40 ft. Midsummer fish sit out in 50 to 120 ft before dropping to 20 to 80 ft for winter. Summer lake trout concentrate at Deep basin, a prime-rated deep basin around 120 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 (44 ft) | Casting spoon over shoals, Jerkbait (shallow) |
| Summer | 50 to 120 ft | dawn | Deep basin (120 ft) | White tube jig (deep), Magnum spoon on downrigger |
| Fall | 10 to 50 ft | dusk & dawn | Main-lake point (44 ft) | Heavy casting spoon, Jigging rap over reefs |
| Winter | 20 to 80 ft | dawn | Break off the point (58 ft) | White tube jig, Airplane jig |
Spring cisco (lake herring) on O.S.A. Lake hold shallow, usually 10 to 40 ft. They move out to 40 to 80 ft in summer and finish the year down in 20 to 60 ft. Put Break off the point first on the milk run — a drop-off near 58 ft that grades prime for winter. The feeding windows run early morning. The summer box starts with a vertical flutter spoon (small) or a drop-shot micro plastic.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 10 to 40 ft | dawn & dusk | Deep basin (120 ft) | Small silver spoon, Tiny swim jig (white) |
| Summer | 40 to 80 ft | dawn | Break off the point (58 ft) | Vertical flutter spoon (small), Drop-shot micro plastic |
| Fall | 5 to 25 ft | dusk & dawn | open water | Small casting spoon, Inline spinner (silver) |
| Winter | 20 to 60 ft | dawn | Break off the point (58 ft) | Small jigging spoon (glow/silver), Tungsten jig + minnow head |
Structure-wise the chart holds 7 features, led in depth by Deep basin at roughly 120 ft.
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 O.S.A. Lake specifically, so confirm the current rules before you fish.
Check the official Ontario fishing regulations →
O.S.A. Lake is about 120 ft (37 m) deep at its deepest point. The depth data here comes from a transect sounding survey by the Ontario MNRF.
Anglers target lake trout, cisco (lake herring) on O.S.A. Lake.
Deep basin is the top-rated area: a deep basin in about 120 ft of water that rates prime for lake trout in summer. The map above holds the full rated-spot list for every species and season.
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 O.S.A. 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.
Teardrop Lake 1 mi · Muriel Lake 2 mi · George Lake 2 mi · A.Y. Jackson Lake 2 mi · Freeland Lake 2 mi · Acid Lake 2 mi · Lumsden Lake 2 mi · Cranberry Bog 2 mi · Killarney Lake 3 mi · Cave Lake 3 mi · Threenarrows Lake 3 mi · Little Superior Lake 4 mi
See how O.S.A. Lake stacks up: best lake trout lakes in Ontario · best cisco (lake herring) lakes in Ontario
More water nearby: Sudbury District fishing maps (868 charts). Browse all Ontario 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.