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75-acre lake in Algoma District, Ontario. The lake tops out around 60 ft. The depth data here comes from the Ontario MNRF survey of 1972, a decades-old survey (a transect sounding survey). The season-by-season read for each species follows, from the map's own numbers.
Upper Grindstone Lake maps at 75 acres behind 2.7 miles of shoreline. 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. Littoral water — the productive band under ~15 ft — makes up 42% of this chart. Call it 1.1 mi long by 0.3 mi wide at the broadest reach. Algoma District claims this one. Grindstone Lake sits 1 mi southwest — the closest neighbouring chart.
When the water first warms, brook trout slide up into 2 to 15 ft. Summer is a 10 to 30 ft game here, winter a 3 to 20 ft one. Start at Break off the point. It's a drop-off holding about 29 ft of water and rates prime come summer. The feeding windows run early morning and the evening. Keep a small spoon fished deep or a trolled lake-clear wobbler + worm rigged through the warm months.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 2 to 15 ft | dawn & dusk | Main-lake point (6 ft) | Small inline spinner (gold), Tiny spoon |
| Summer | 10 to 30 ft | dawn & dusk | Break off the point (29 ft) | Small spoon fished deep, Trolled lake-clear wobbler + worm |
| Fall | 2 to 15 ft | midday & dawn | Main-lake point (6 ft) | Small spoon (orange), Spinner |
| Winter | 3 to 20 ft | dawn | Shallow bay flat (8 ft) | Small jigging spoon, Tungsten jig + plastic |
6 pieces of structure are mapped here — Deep basin, around 60 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 Upper Grindstone Lake specifically, so confirm the current rules before you fish.
Check the official Ontario fishing regulations →
Upper Grindstone Lake is about 60 ft (18 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 Upper Grindstone Lake.
Break off the point is the top-rated area: a drop-off in about 29 ft of water that rates prime for brook trout in summer. 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 Upper 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.
Grindstone Lake 1 mi · Rioux L. 36 1 mi · Izaak Lake 2 mi · Sturgeon L. 27 2 mi · Rioux Lake 35 2 mi · Sturgeon Lake 33 3 mi · Rioux Lake 16 3 mi · Rioux Lake 28 4 mi · Long-tail L. 5 mi · Squawk L. 5 mi · Rioux Lake 10 5 mi · Jellybean L. 5 mi
See how Upper 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.