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77-acre lake in Algoma District, Ontario. The lake tops out around 40 ft. The depth data here comes from the Ontario MNRF survey of 1972, a decades-old survey (a transect sounding survey). Species by species, here's what the data says the year looks like.
On the chart, Grindstone Lake draws 77 acres inside 2.9 miles of shoreline — one island included. With a shoreline index of 2.4, this water is all arms and coves — edge habitat well beyond its acreage. Littoral water — the productive band under ~15 ft — makes up 78% of this chart. Call it 0.8 mi long by 0.4 mi wide at the broadest reach. You'll find it in Algoma District. The nearest mapped water is Upper Grindstone Lake, 1 mi to the northeast.
Start shallow in spring: brook trout sit in 2 to 15 ft that time of year. Summer pushes them deeper, 10 to 30 ft, and winter fish settle into 3 to 20 ft. The spot to know is Main-lake point, a point in about 4 ft of water that rates prime for brook trout in spring. Warm-month bites cluster around early morning and the evening. Throw a small spoon fished deep or a trolled lake-clear wobbler + worm until the fish tell you otherwise.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 2 to 15 ft | dawn & dusk | Main-lake point (4 ft) | Small inline spinner (gold), Tiny spoon |
| Summer | 10 to 30 ft | dawn & dusk | Break off the point (7 ft) | Small spoon fished deep, Trolled lake-clear wobbler + worm |
| Fall | 2 to 15 ft | midday & dawn | Main-lake point (4 ft) | Small spoon (orange), Spinner |
| Winter | 3 to 20 ft | dawn | Break off the point (7 ft) | Small jigging spoon, Tungsten jig + plastic |
Structure-wise the chart holds 6 features, led in depth by Deep basin at roughly 38 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 Grindstone Lake specifically, so confirm the current rules before you fish.
Check the official Ontario fishing regulations →
Grindstone Lake is about 40 ft (12 m) deep at its deepest point. The depth data here comes from the Ontario MNRF survey of 1972, a decades-old survey (a transect sounding survey).
Anglers target brook trout on Grindstone Lake.
Main-lake point is the top-rated area: a point in about 4 ft of water that rates prime for brook trout in spring. The map above holds the full rated-spot list for every 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 Grindstone 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.
Upper Grindstone Lake 1 mi · Rioux L. 36 2 mi · Sturgeon L. 27 2 mi · Sturgeon Lake 33 2 mi · Izaak Lake 2 mi · Rioux Lake 35 3 mi · Rioux Lake 16 3 mi · Long-tail L. 4 mi · Squawk L. 4 mi · Jellybean L. 5 mi · Little Lafoe Lake 5 mi · Rioux Lake 28 5 mi
See how Grindstone 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.