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41-acre lake in Cochrane District, Ontario. The lake tops out around 16 ft. The contours come from a model of the real basin shape and its known max depth. Read them as probabilities, not soundings, and keep them out of navigation decisions. The season-by-season read for each species follows, from the map's own numbers.
Traced from the shoreline, Extension Lake runs 41 acres with 1.9 miles of edge. Index 2.1 on the shoreline: a few honest points and pockets, nothing labyrinthine. About 95% of the surface sits shallower than 15 ft on the modeled chart — that's the weed-and-bait zone. Tip to tip the water measures near 0.7 mi with a 0.2-mi widest point. The water lies in Cochrane District. For a second option, Grey Lake lies 1 mi southwest.
The spring pattern is a shallow one: brook trout in 2 to 15 ft. Midsummer fish sit out in 5 to 16 ft before dropping to 2 to 16 ft for winter. The spot to know is Deep basin, a deep basin in about 14 ft of water that rates prime for brook trout in summer. Plan around early morning and the evening in the warm months. Summer baits: a small spoon fished deep or a trolled lake-clear wobbler + worm gets it done.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 2 to 15 ft | dawn & dusk | Main-lake point (8 ft) | Small inline spinner (gold), Tiny spoon |
| Summer | 5 to 16 ft | dawn & dusk | Deep basin (14 ft) | Small spoon fished deep, Trolled lake-clear wobbler + worm |
| Fall | 2 to 15 ft | midday & dawn | Main-lake point (8 ft) | Small spoon (orange), Spinner |
| Winter | 2 to 16 ft | dawn | Deep basin (14 ft) | Small jigging spoon, Tungsten jig + plastic |
Early season yellow perch use the shallows, holding in 3 to 12 ft. Expect a summer slide to 5 to 16 ft, then a winter hold in 5 to 16 ft. Put Shallow bay flat first on the milk run — a weed flat near 3 ft that grades prime for spring. In summer the feeding windows fall in early morning. Tie on a drop-shot micro plastics or a small spoon tipped with worm and you're in the game.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 3 to 12 ft | midday & dawn | Shallow bay flat (3 ft) | Small jig + curly tail, Perch-pattern micro crank |
| Summer | 5 to 16 ft | dawn | Deep basin (14 ft) | Drop-shot micro plastics, Small spoon tipped with worm |
| Fall | 5 to 16 ft | midday | Deep basin (14 ft) | Jigging spoon (small), Perch rig / spreader |
| Winter | 5 to 16 ft | midday & dawn | Deep basin (14 ft) | Tungsten jig + spikes, Rattle spoon (small) |
In spring, northern pike run shallow here, mostly 2 to 8 ft. Summer pushes them deeper, 5 to 16 ft, and winter fish settle into 5 to 15 ft. Shallow bay flat is the standout, a weed flat at roughly 3 ft, rated prime for spring northern pike. Time it for early morning and the evening. You won't need more than a bucktail or a weedless spoon over cabbage most summer days.
| 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 | 5 to 16 ft | dawn & dusk | Break off the point (7 ft) | Bucktail, Weedless spoon over cabbage |
| Fall | 5 to 16 ft | midday & dawn | Break off the point (7 ft) | Big rubber (Bull Dawg style), Husky-style jerkbait |
| Winter | 5 to 15 ft | midday | Shallow bay flat (3 ft) | Tip-ups, Large jigging spoon |
5 pieces of structure are mapped here — Deep basin, around 14 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 Extension Lake specifically, so confirm the current rules before you fish.
Check the official Ontario fishing regulations →
Extension Lake is about 16 ft (5 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 brook trout, yellow perch, northern pike on Extension Lake.
Shallow bay flat is the top-rated area: a weed flat in about 3 ft of water that rates prime for yellow perch 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 Extension 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.
Grey Lake 1 mi · Potvin Lake 1 mi · Alexander Lake 1 mi · Cootie Lake 2 mi · Jessups L. 2 mi · Lord Lake 2 mi · Fargo Lake 3 mi · McEvay L. 18 4 mi · Sylvia Lake 4 mi · Watabeag Lake 5 mi · Cariboo Lake 5 mi · Shuker Lake 5 mi
See how Extension Lake stacks up: best northern pike lakes in Ontario · best yellow perch lakes in Ontario · best brook trout lakes in Ontario
More water nearby: Cochrane District fishing maps (673 charts). Browse all Ontario fishing maps or 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.