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284-acre lake in Cochrane District, Ontario. The lake tops out around 10 ft. The depth data here comes from a transect sounding survey by the Ontario MNRF. Species by species, here's what the data says the year looks like.
Drawn out, this is 285 acres of water rimmed by 3.1 miles of bank. Its 1.3 shoreline index means few bank features; the contours below do the pattern work. All of it is shallow-zone water — under ~15 ft across the entire basin, so the food chain has the run of the place. The basin spans about 1 mi end to end and 0.8 mi across at its widest. The water lies in Cochrane District. The nearest mapped water is Rufus Lake, 3 mi to the south.
Early season walleye use the shallows, holding in 3 to 10 ft. Even in summer they hold at 3 to 10 ft; winter keeps them in 3 to 10 ft. The chart's best answer is Break off the point — drop-off, 9 ft, prime for fall. Best bite is the evening and early morning. Tie on a crawler harness on bottom bouncer or a deep crankbait (trolled) and you're in the game.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 3 to 10 ft | dusk & dawn | Main-lake point (4 ft) | 1/8 oz jig + minnow, Hair jig |
| Summer | 3 to 10 ft | dusk & dawn | Break off the point (9 ft) | Crawler harness on bottom bouncer, Deep crankbait (trolled) |
| Fall | 3 to 10 ft | dusk & night | Break off the point (9 ft) | Jigging rap, Jig + big minnow |
| Winter | 3 to 10 ft | dusk & dawn | Deep basin (10 ft) | Jigging spoon + minnow head, Rattle bait |
Spring yellow perch on Flatt Lake hold shallow, usually 3 to 10 ft. Depth-wise the year is flat: 3 to 10 ft in summer, 3 to 10 ft once it turns cold. The chart's best answer is Shallow bay flat — weed flat, 3 ft, prime for spring. Prime time lands in early morning. The summer box starts with a drop-shot micro plastics or a small spoon tipped with worm.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 3 to 10 ft | midday & dawn | Shallow bay flat (3 ft) | Small jig + curly tail, Perch-pattern micro crank |
| Summer | 3 to 10 ft | dawn | Deep basin (10 ft) | Drop-shot micro plastics, Small spoon tipped with worm |
| Fall | 3 to 10 ft | midday | Deep basin (10 ft) | Jigging spoon (small), Perch rig / spreader |
| Winter | 3 to 10 ft | midday & dawn | Deep basin (10 ft) | Tungsten jig + spikes, Rattle spoon (small) |
Spring puts northern pike in skinny water — 2 to 8 ft is the zone. As the season builds they drop to 3 to 10 ft, wintering in 3 to 10 ft. Spring northern pike concentrate at Shallow bay flat, a prime-rated weed flat around 3 ft. Warm-month bites cluster around early morning and the evening. A bucktail or a weedless spoon over cabbage covers the summer program.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 2 to 8 ft | midday & dawn | Shallow bay flat (3 ft) | #5 inline spinner, Spoon (red/white) |
| Summer | 3 to 10 ft | dawn & dusk | Shallow bay flat (3 ft) | Bucktail, Weedless spoon over cabbage |
| Fall | 3 to 10 ft | midday & dawn | Shallow bay flat (3 ft) | Big rubber (Bull Dawg style), Husky-style jerkbait |
| Winter | 3 to 10 ft | midday | Shallow bay flat (3 ft) | Tip-ups, Large jigging spoon |
The chart marks 6 structure features on Flatt Lake; the deepest is Deep basin at about 10 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 Flatt Lake specifically, so confirm the current rules before you fish.
Check the official Ontario fishing regulations →
Flatt Lake is about 10 ft (3 m) deep at its deepest point. The depth data here comes from a transect sounding survey by the Ontario MNRF.
Anglers target walleye, yellow perch, northern pike on Flatt Lake.
Break off the point is the top-rated area: a drop-off in about 9 ft of water that rates prime for walleye in fall. Every other rated spot, per species and season, is on the map above.
For walleye, the summer bite is best in the evening and 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 Flatt 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.
Rufus Lake 3 mi · Lepp Lake 4 mi · Opasatika Lake 4 5 mi · Opasakita Lake 12 6 mi · Little Rice Lake 7 mi · Buchanan Lake 7 mi · Penelton Lake 7 mi · Opasatika Lake 16 7 mi · Opasatika Lake 15 8 mi · Big Rice Lake 9 mi · South Moosehorn Lake 9 mi · Opasatika L. 14 9 mi
See how Flatt Lake stacks up: best walleye lakes in Ontario · best northern pike lakes in Ontario · best yellow perch lakes in Ontario
More water nearby: Cochrane District fishing maps (673 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.