Sign inSign up free Sign inSign up free Sign inSign up freeLake depth chart
Today's read
Recent public catches load as you reach this section.
1,125-acre lake in Thunder Bay District, Ontario. The lake tops out around 55 ft. Depth here is modeled from the true shoreline and max depth rather than surveyed; use it to plan, not to navigate. Below is the species-by-species picture, pulled from the same data the map uses.
Grassy L. maps at 1,127 acres behind 21.2 miles of shoreline, broken up by an island. A development index of 4.5 means a maze of bays and points: far more casting targets than a round bowl of the same size. The shallow band under 15 ft claims about 65% of the surface on the model — that's where the groceries are. Figure 3.6 mi of water from one end to the other, 2.4 mi at the beam. It sits in Thunder Bay District. If the bite dies, Rude Lake is 2 mi to the northwest.
In spring, lake whitefish run shallow here, mostly 15 to 45 ft. Summer pushes them deeper, 17 to 55 ft, and winter fish settle into 17 to 55 ft. Deep basin is the standout, a deep basin at roughly 47 ft, rated prime for summer lake whitefish. Time it for early morning. You won't need more than a blade bait vertical or a small jigging spoon most summer days.
Depth note: when a documented seasonal range extends below this chart, the table shows the deepest mapped working water, not a verified holding depth.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 15 to 45 ft | midday & dawn | Break off the point (25 ft) | Small jig + waxworm, Blade bait (small) |
| Summer | 17 to 55 ft chart-limited; documented 40 to 90 ft | dawn | Deep basin (47 ft) | Blade bait vertical, Small jigging spoon |
| Fall | 8 to 30 ft | dusk | Break off the point (25 ft) | Small spoon (gold), Jig + plastic larva |
| Winter | 17 to 55 ft chart-limited; documented 25 to 70 ft | midday & dawn | Deep basin (47 ft) | Jigging spoon + bead chain, Tungsten jig + waxie |
In spring, cisco (lake herring) run shallow here, mostly 10 to 40 ft. Summer pushes them deeper, 17 to 55 ft, and winter fish settle into 17 to 55 ft. Deep basin is the standout, a deep basin at roughly 47 ft, rated prime for summer cisco (lake herring). Time it for early morning. You won't need more than a vertical flutter spoon (small) or a drop-shot micro plastic most summer days.
Depth note: when a documented seasonal range extends below this chart, the table shows the deepest mapped working water, not a verified holding depth.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 10 to 40 ft | dawn & dusk | Deep basin (47 ft) | Small silver spoon, Tiny swim jig (white) |
| Summer | 17 to 55 ft chart-limited; documented 40 to 80 ft | dawn | Deep basin (47 ft) | Vertical flutter spoon (small), Drop-shot micro plastic |
| Fall | 5 to 25 ft | dusk & dawn | Break off the point (25 ft) | Small casting spoon, Inline spinner (silver) |
| Winter | 17 to 55 ft chart-limited; documented 20 to 60 ft | dawn | Deep basin (47 ft) | Small jigging spoon (glow/silver), Tungsten jig + minnow head |
The spring pattern is a shallow one: walleye in 4 to 15 ft. Midsummer fish sit out in 15 to 35 ft before dropping to 20 to 40 ft for winter. The spot to know is Break off the point, a drop-off in about 25 ft of water that rates prime for walleye in fall. Plan around the evening and early morning in the warm months. Summer baits: a crawler harness on bottom bouncer or a deep crankbait (trolled) gets it done.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 4 to 15 ft | dusk & dawn | Main-lake point (14 ft) | 1/8 oz jig + minnow, Hair jig |
| Summer | 15 to 35 ft | dusk & dawn | Break off the point (25 ft) | Crawler harness on bottom bouncer, Deep crankbait (trolled) |
| Fall | 12 to 40 ft | dusk & night | Break off the point (25 ft) | Jigging rap, Jig + big minnow |
| Winter | 20 to 40 ft | dusk & dawn | Break off the point (25 ft) | Jigging spoon + minnow head, Rattle bait |
In spring, yellow perch run shallow here, mostly 3 to 12 ft. Midsummer fish sit out in 10 to 30 ft before dropping to 15 to 35 ft for winter. Spring yellow perch concentrate at Shallow bay flat, a prime-rated weed flat around 6 ft. Fish it in early morning and you'll meet the bite. You won't need more than a drop-shot micro plastics or a small spoon tipped with worm most summer days.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 3 to 12 ft | midday & dawn | Shallow bay flat (6 ft) | Small jig + curly tail, Perch-pattern micro crank |
| Summer | 10 to 30 ft | dawn | Break off the point (25 ft) | Drop-shot micro plastics, Small spoon tipped with worm |
| Fall | 12 to 35 ft | midday | Break off the point (25 ft) | Jigging spoon (small), Perch rig / spreader |
| Winter | 15 to 35 ft | midday & dawn | Break off the point (25 ft) | Tungsten jig + spikes, Rattle spoon (small) |
Early season northern pike use the shallows, holding in 2 to 8 ft. Summer is an 8 to 20 ft game here, winter a 5 to 15 ft one. The chart's best answer is Shallow bay flat — weed flat, 6 ft, prime for spring. Best bite is early morning and the evening. Tie on a bucktail or a weedless spoon over cabbage and you're in the game.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 2 to 8 ft | midday & dawn | Shallow bay flat (6 ft) | #5 inline spinner, Spoon (red/white) |
| Summer | 8 to 20 ft | dawn & dusk | Shallow bay flat (6 ft) | Bucktail, Weedless spoon over cabbage |
| Fall | 6 to 18 ft | midday & dawn | Shallow bay flat (6 ft) | Big rubber (Bull Dawg style), Husky-style jerkbait |
| Winter | 5 to 15 ft | midday | Shallow bay flat (6 ft) | Tip-ups, Large jigging spoon |
In spring, rock bass run shallow here, mostly 2 to 10 ft. Summer pushes them deeper, 5 to 20 ft, and winter fish settle into 12 to 30 ft. Main-lake point is the standout, a point at roughly 14 ft, rated prime for summer rock bass. Time it for the evening. You won't need more than a ned rig (small) or a marabou jig most summer days.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 2 to 10 ft | midday & dawn | open water | 1/16 oz jig + grub, Small inline spinner |
| Summer | 5 to 20 ft | dusk | Main-lake point (14 ft) | Ned rig (small), Marabou jig |
| Fall | 8 to 22 ft | midday | Main-lake point (14 ft) | Small tube jig, Inline spinner |
| Winter | 12 to 30 ft | midday | Break off the point (25 ft) | Tungsten jig + plastic, Small spoon + spike |
6 pieces of structure are mapped here — Deep basin, around 47 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 Grassy L. specifically, so confirm the current rules before you fish.
Check the official Ontario fishing regulations →
Grassy L. is about 55 ft (17 m) deep at its deepest point. The contours here are modeled from the water's real shape and maximum depth, so treat them as a rough guide.
Anglers target lake whitefish, cisco (lake herring), walleye, yellow perch, northern pike, rock bass on Grassy L..
Deep basin is the top-rated area: a deep basin in about 47 ft of water that rates prime for lake whitefish in summer. Scroll up to the map for the complete spot list by species and season.
For lake whitefish, 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 Grassy L. 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.
Rude Lake 2 mi · Sparkling Lake 6 mi · Harmon Lake 7 mi · Empire Lake 9 mi · Brightsand Lake 10 mi · Metionga L. 12 mi · Waterhouse Lake 13 mi · Kashishibog Lake 13 mi · Cibber L. 14 mi · Wapikaimaski L. 15 mi · Gaal Lake 16 mi · Little Metionga Lake 17 mi
See how Grassy L. stacks up: best walleye lakes in Ontario · best northern pike lakes in Ontario · best yellow perch lakes in Ontario · best lake whitefish lakes in Ontario
More water nearby: Thunder Bay District fishing maps (662 charts). Browse all Ontario fishing maps. See every water on DepthScout. 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.