Sign inSign up free Sign inSign up free Sign inSign up freeShared by DepthScout anglers. Exact spots stay private, always.
394-acre lake in Frontenac County, Ontario. The lake tops out around 66 ft. The depth data here comes from the Ontario MNRF survey of 1982 (a transect sounding survey). What follows comes from the same scoring engine that paints the spots above.
On the chart, Grindstone Lake draws 396 acres inside 9.6 miles of shoreline — 3 islands included. With a shoreline index of 3.4, this water is all arms and coves — edge habitat well beyond its acreage. Roughly 25% of the water is 15 ft or less, the band where the food chain lives. Call it 1.6 mi long by 1.1 mi wide at the broadest reach. The water lies in Frontenac County. For a second option, Little Mosque Lake lies 1 mi southeast.
In spring, splake run shallow here, mostly 5 to 25 ft. Summer pushes them deeper, 25 to 60 ft, and winter fish settle into 10 to 45 ft. Break off the point is the standout, a drop-off at roughly 34 ft, rated prime for summer splake. Time it for early morning and the evening. You won't need more than a trolled spoon at the thermocline or a white tube jig (deep) most summer days.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 5 to 25 ft | dawn & dusk | Main-lake point (14 ft) | Small casting spoon (gold/orange), Inline spinner |
| Summer | 25 to 60 ft | dawn & dusk | Break off the point (34 ft) | Trolled spoon at the thermocline, White tube jig (deep) |
| Fall | 10 to 35 ft | dawn & dusk | Main-lake point (14 ft) | Casting spoon, Jerkbait |
| Winter | 10 to 45 ft | dawn | Break off the point (34 ft) | Jigging spoon tipped with minnow head, Small white tube |
Early season lake whitefish use the shallows, holding in 15 to 45 ft. Expect a summer slide to 20 to 66 ft, then a winter hold in 20 to 66 ft. Put Deep basin first on the milk run — a deep basin near 64 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 | Break off the point (34 ft) | Small jig + waxworm, Blade bait (small) |
| Summer | 20 to 66 ft | dawn | Deep basin (64 ft) | Blade bait vertical, Small jigging spoon |
| Fall | 8 to 30 ft | dusk | Main-lake point (14 ft) | Small spoon (gold), Jig + plastic larva |
| Winter | 20 to 66 ft | midday & dawn | Deep basin (64 ft) | Jigging spoon + bead chain, Tungsten jig + waxie |
Early season cisco (lake herring) use the shallows, holding in 10 to 40 ft. Expect a summer slide to 20 to 66 ft, then a winter hold in 20 to 60 ft. Put Deep basin first on the milk run — a deep basin near 64 ft that grades prime for summer. In summer the feeding windows fall in early morning. Tie on a vertical flutter spoon (small) or a drop-shot micro plastic and you're in the game.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 10 to 40 ft | dawn & dusk | Break off the point (34 ft) | Small silver spoon, Tiny swim jig (white) |
| Summer | 20 to 66 ft | dawn | Deep basin (64 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 | Deep basin (64 ft) | Small jigging spoon (glow/silver), Tungsten jig + minnow head |
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 4 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 (4 ft) | Small jig + curly tail, Perch-pattern micro crank |
| Summer | 10 to 30 ft | dawn | Break off the point (34 ft) | Drop-shot micro plastics, Small spoon tipped with worm |
| Fall | 12 to 35 ft | midday | Break off the point (34 ft) | Jigging spoon (small), Perch rig / spreader |
| Winter | 15 to 35 ft | midday & dawn | Break off the point (34 ft) | Tungsten jig + spikes, Rattle spoon (small) |
Start shallow in spring: smallmouth bass sit in 3 to 12 ft that time of year. Summer pushes them deeper, 10 to 30 ft, and winter fish settle into 20 to 45 ft. The spot to know is Main-lake point, a point in about 14 ft of water that rates prime for smallmouth bass in fall. Warm-month bites cluster around early morning and the evening. Throw a drop shot (goby/minnow) or a ned rig until the fish tell you otherwise.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 3 to 12 ft | dawn & dusk | Main-lake point (14 ft) | Ned rig, Tube jig |
| Summer | 10 to 30 ft | dawn & dusk | Main-lake point (14 ft) | Drop shot (goby/minnow), Ned rig |
| Fall | 8 to 25 ft | midday & dawn | Main-lake point (14 ft) | Jerkbait, Blade bait |
| Winter | 20 to 45 ft | midday | Break off the point (34 ft) | Blade bait, Hair jig |
The spring pattern is a shallow one: largemouth bass in 2 to 10 ft. As the season builds they drop to 8 to 20 ft, wintering in 15 to 35 ft. Top water on the chart: Shallow bay flat, a weed flat in the 4 ft range, prime in spring. Time it for early morning and the evening. Summer baits: a texas-rigged 10" worm or a deep-diving crankbait gets it done.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 2 to 10 ft | dawn & dusk | Shallow bay flat (4 ft) | Spinnerbait, Chatterbait |
| Summer | 8 to 20 ft | dawn & dusk | Main-lake point (14 ft) | Texas-rigged 10" worm, Deep-diving crankbait |
| Fall | 4 to 15 ft | midday & dawn | Main-lake point (14 ft) | Squarebill crankbait (shad), Spinnerbait |
| Winter | 15 to 35 ft | midday | Break off the point (34 ft) | Blade bait, Jigging spoon |
Grindstone Lake also holds pumpkinseed (2 to 10 ft in summer). Pick any of them on the map above for rated spots and bait picks.
Grindstone Lake carries 6 mapped structure features, topping out (or rather bottoming out) at Deep basin, about 64 ft down.
Access data: Land Information Ontario — Fishing Access Point. Confirm conditions and fees locally before you launch.
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 66 ft (20 m) deep at its deepest point. The depth data here comes from the Ontario MNRF survey of 1982 (a transect sounding survey).
Anglers target splake, lake whitefish, cisco (lake herring), yellow perch, smallmouth bass, largemouth bass, pumpkinseed on Grindstone Lake.
Break off the point is the top-rated area: a drop-off in about 34 ft of water that rates prime for splake in summer. Every other rated spot, per species and season, is on the map above.
For splake, 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.
Little Mosque Lake 1 mi · Mosque Lake 2 mi · Palmerston Lake 5 mi · Mackie Lake 5 mi · Crib Lake 5 mi · Little Green Lake 5 mi · Brule Lake 5 mi · Granite Lake 6 mi · Summit Lake 6 mi · Buckshot Lake 6 mi · Wolfe Lake 7 mi · Ardoch Lake 7 mi
See how Grindstone Lake stacks up: best largemouth bass lakes in Ontario · best smallmouth bass lakes in Ontario · best yellow perch lakes in Ontario · best lake whitefish lakes in Ontario
More water nearby: Frontenac County fishing maps (127 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.