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50-acre lake in Algoma District, Ontario. The lake tops out around 40 ft. The depth data here comes from the Ontario MNRF survey of 2003 (a transect sounding survey). Below is the species-by-species picture, pulled from the same data the map uses.
On the chart, Grosjean Lake draws 51 acres inside 3.3 miles of shoreline — 4 islands included. The 3.3 development index tells the story — a convoluted bank whose fishable edge far outruns the acreage. Littoral water — the productive band under ~15 ft — makes up 58% of this chart. Call it 0.9 mi long by 0.2 mi wide at the broadest reach. The water lies in Algoma District. For a second option, Benspreng Lake lies 1 mi northeast.
Spring puts brook trout in skinny water — 2 to 15 ft is the zone. Warm water sends them out to 10 to 30 ft; cold water stacks them in 3 to 20 ft. Break off the point is the standout, a drop-off at roughly 11 ft, rated prime for summer brook trout. Plan around early morning and the evening in the warm months. A small spoon fished deep or a trolled lake-clear wobbler + worm covers the summer program.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 2 to 15 ft | dawn & dusk | Main-lake point (5 ft) | Small inline spinner (gold), Tiny spoon |
| Summer | 10 to 30 ft | dawn & dusk | Break off the point (11 ft) | Small spoon fished deep, Trolled lake-clear wobbler + worm |
| Fall | 2 to 15 ft | midday & dawn | Main-lake point (5 ft) | Small spoon (orange), Spinner |
| Winter | 3 to 20 ft | dawn | Break off the point (11 ft) | Small jigging spoon, Tungsten jig + plastic |
6 pieces of structure are mapped here — Deep basin, around 37 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 Grosjean Lake specifically, so confirm the current rules before you fish.
Check the official Ontario fishing regulations →
Grosjean Lake is about 40 ft (12 m) deep at its deepest point. The depth data here comes from the Ontario MNRF survey of 2003 (a transect sounding survey).
Anglers target brook trout on Grosjean Lake.
Break off the point is the top-rated area: a drop-off in about 11 ft of water that rates prime for brook trout in summer. Scroll up to the map for the complete spot list by species and season.
For brook trout, the summer bite is best in early morning and the evening. Each species page section below lists the seasonal windows, and the map shows a live NOW badge when you're inside one.
Fishing on Grosjean 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.
Benspreng Lake 1 mi · Great Scott Lake 1 mi · Leaping Fox Lake 1 mi · Mushroom Lake 2 mi · Cable Lake 2 mi · Emily Murphy L. 2 mi · Post L. 2 mi · McKinney L. 2 mi · East Caribou Lake 3 mi · Pearl Lake 3 mi · Irene Parlby L. 4 mi · Highland Lake 4 mi
See how Grosjean Lake stacks up: best brook trout lakes in Ontario
More water nearby: Algoma District fishing maps (1026 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.