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171-acre lake in Algoma District, Ontario. The lake tops out around 46 ft. The depth chart comes from Ontario Ministry of Natural Resources and Forestry bathymetric survey data, so the contours are survey-derived rather than computer-modeled. Species by species, here's what the data says the year looks like.
Traced from the shoreline, Foucault L. 42 runs 171 acres with 4.1 miles of edge. A development index of 2.2 means a maze of bays and points: far more casting targets than a round bowl of the same size. Roughly 77% of the water is 15 ft or less, the band where the food chain lives. End to end it runs roughly 1.7 mi, about 0.5 mi across. The water lies in Algoma District. The nearest mapped water is Big Trout L., 3 mi to the west.
Spring puts lake trout in skinny water — 10 to 40 ft is the zone. As the season builds they drop to 14 to 46 ft, wintering in 12 to 46 ft. Summer lake trout concentrate at Deep basin, a prime-rated deep basin around 41 ft. Warm-month bites cluster around early morning. A white tube jig (deep) or a magnum spoon on downrigger covers the summer program.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 10 to 40 ft | dawn & dusk | Main-lake point (1 ft) | Casting spoon over shoals, Jerkbait (shallow) |
| Summer | 14 to 46 ft | dawn | Deep basin (41 ft) | White tube jig (deep), Magnum spoon on downrigger |
| Fall | 9 to 46 ft | dusk & dawn | Main-lake point (1 ft) | Heavy casting spoon, Jigging rap over reefs |
| Winter | 12 to 46 ft | dawn | Deep basin (41 ft) | White tube jig, Airplane jig |
Early season lake whitefish use the shallows, holding in 15 to 45 ft. Expect a summer slide to 14 to 46 ft, then a winter hold in 14 to 46 ft. Put Deep basin first on the milk run — a deep basin near 41 ft that grades prime for summer. In summer the feeding windows fall in early morning. Tie on a blade bait vertical or a small jigging spoon and you're in the game.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 15 to 45 ft | midday & dawn | open water | Small jig + waxworm, Blade bait (small) |
| Summer | 14 to 46 ft | dawn | Deep basin (41 ft) | Blade bait vertical, Small jigging spoon |
| Fall | 8 to 30 ft | dusk | Break off the point (1 ft) | Small spoon (gold), Jig + plastic larva |
| Winter | 14 to 46 ft | midday & dawn | Deep basin (41 ft) | Jigging spoon + bead chain, Tungsten jig + waxie |
Come spring, look for yellow perch tight to the bank in 3 to 12 ft. Expect a summer slide to 10 to 30 ft, then a winter hold in 15 to 35 ft. Start at Shallow bay flat. It's a weed flat holding about 1 ft of water and rates prime come spring. Prime time lands in early morning. A drop-shot micro plastics or a small spoon tipped with worm is the honest summer answer here.
| 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 (1 ft) | Drop-shot micro plastics, Small spoon tipped with worm |
| Fall | 12 to 35 ft | midday | Deep basin (41 ft) | Jigging spoon (small), Perch rig / spreader |
| Winter | 15 to 35 ft | midday & dawn | Deep basin (41 ft) | Tungsten jig + spikes, Rattle spoon (small) |
Foucault L. 42 carries 6 mapped structure features, topping out (or rather bottoming out) at Deep basin, about 41 ft down.
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 Foucault L. 42 specifically, so confirm the current rules before you fish.
Check the official Ontario fishing regulations →
Foucault L. 42 is about 46 ft (14 m) deep at its deepest point. The depth chart comes from Ontario Ministry of Natural Resources and Forestry bathymetric survey data, so the contours are survey-derived rather than computer-modeled.
Anglers target lake trout, lake whitefish, yellow perch on Foucault L. 42.
Deep basin is the top-rated area: a deep basin in about 41 ft of water that rates prime for lake trout in summer. Open the map above to see every rated spot for each 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 Foucault L. 42 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.
Big Trout L. 3 mi · Lidstone Lake 3 mi · Little Trout Lake 4 mi · Monestime L. 5 4 mi · Lac aux Sables 4 mi · Foucault L. 10 5 mi · Gervais L. 1 5 mi · Five Star Lake 6 mi · Frying Pan Lake 6 mi · Pandion L. 6 mi · Boumage Lake 6 mi · Little Touch L. 6 mi
See how Foucault L. 42 stacks up: best yellow perch lakes in Ontario · best lake trout lakes in Ontario · best lake whitefish lakes in Ontario
More water nearby: Algoma District fishing maps (1026 charts). Browse all Ontario fishing maps or see every water on DepthScout. Bathymetry: published agency survey data. 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.