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66-acre lake in Nipissing District, Ontario. The lake tops out around 53 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. What the data behind the map says about each species, season by season:
On the chart, McDiarmid Lake draws 67 acres inside 3 miles of shoreline. That shoreline is heavily fingered (development index 2.7) — bays, points and pockets everywhere, which multiplies the fishable edge. About 29% of the surface sits shallower than 15 ft on the modeled chart — that's the weed-and-bait zone. End to end it runs roughly 0.9 mi, about 0.3 mi across. The water lies in Nipissing District. Closest neighbour on DepthScout: Fanny Lake, 1 mi southwest of here.
Come spring, look for cisco (lake herring) tight to the bank in 10 to 40 ft. Expect a summer slide to 16 to 53 ft, then a winter hold in 16 to 53 ft. Start at Deep basin. It's a deep basin holding about 45 ft of water and rates prime come summer. Prime time lands in early morning. A vertical flutter spoon (small) or a drop-shot micro plastic is the honest summer answer here.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 10 to 40 ft | dawn & dusk | Deep basin (45 ft) | Small silver spoon, Tiny swim jig (white) |
| Summer | 16 to 53 ft | dawn | Deep basin (45 ft) | Vertical flutter spoon (small), Drop-shot micro plastic |
| Fall | 5 to 25 ft | dusk & dawn | Break off the point (24 ft) | Small casting spoon, Inline spinner (silver) |
| Winter | 16 to 53 ft | dawn | Deep basin (45 ft) | Small jigging spoon (glow/silver), Tungsten jig + minnow head |
Spring walleye on McDiarmid Lake hold shallow, usually 4 to 15 ft. They move out to 15 to 35 ft in summer and finish the year down in 20 to 40 ft. Put Break off the point first on the milk run — a drop-off near 24 ft that grades prime for fall. The feeding windows run the evening and early morning. The summer box starts with a crawler harness on bottom bouncer or a deep crankbait (trolled).
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 4 to 15 ft | dusk & dawn | Main-lake point (13 ft) | 1/8 oz jig + minnow, Hair jig |
| Summer | 15 to 35 ft | dusk & dawn | Break off the point (24 ft) | Crawler harness on bottom bouncer, Deep crankbait (trolled) |
| Fall | 12 to 40 ft | dusk & night | Break off the point (24 ft) | Jigging rap, Jig + big minnow |
| Winter | 20 to 40 ft | dusk & dawn | Break off the point (24 ft) | Jigging spoon + minnow head, Rattle bait |
Early season yellow perch use the shallows, holding in 3 to 12 ft. Expect a summer slide to 10 to 30 ft, then a winter hold in 15 to 35 ft. Put Shallow bay flat first on the milk run — a weed flat near 6 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 (6 ft) | Small jig + curly tail, Perch-pattern micro crank |
| Summer | 10 to 30 ft | dawn | Break off the point (24 ft) | Drop-shot micro plastics, Small spoon tipped with worm |
| Fall | 12 to 35 ft | midday | Break off the point (24 ft) | Jigging spoon (small), Perch rig / spreader |
| Winter | 15 to 35 ft | midday & dawn | Break off the point (24 ft) | Tungsten jig + spikes, Rattle spoon (small) |
In spring, smallmouth bass run shallow here, mostly 3 to 12 ft. Summer pushes them deeper, 10 to 30 ft, and winter fish settle into 20 to 45 ft. Main-lake point is the standout, a point at roughly 13 ft, rated prime for fall smallmouth bass. Time it for early morning and the evening. You won't need more than a drop shot (goby/minnow) or a ned rig most summer days.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 3 to 12 ft | dawn & dusk | Main-lake point (13 ft) | Ned rig, Tube jig |
| Summer | 10 to 30 ft | dawn & dusk | Break off the point (24 ft) | Drop shot (goby/minnow), Ned rig |
| Fall | 8 to 25 ft | midday & dawn | Main-lake point (13 ft) | Jerkbait, Blade bait |
| Winter | 20 to 45 ft | midday | Break off the point (24 ft) | Blade bait, Hair jig |
Come spring, look for rock bass tight to the bank in 2 to 10 ft. Expect a summer slide to 5 to 20 ft, then a winter hold in 12 to 30 ft. Start at Main-lake point. It's a point holding about 13 ft of water and rates prime come summer. Prime time lands in the evening. A ned rig (small) or a marabou jig is the honest summer answer here.
| 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 (13 ft) | Ned rig (small), Marabou jig |
| Fall | 8 to 22 ft | midday | Main-lake point (13 ft) | Small tube jig, Inline spinner |
| Winter | 12 to 30 ft | midday | Break off the point (24 ft) | Tungsten jig + plastic, Small spoon + spike |
6 pieces of structure are mapped here — Deep basin, around 45 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 McDiarmid Lake specifically, so confirm the current rules before you fish.
Check the official Ontario fishing regulations →
McDiarmid Lake is about 53 ft (16 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 cisco (lake herring), walleye, yellow perch, smallmouth bass, rock bass on McDiarmid Lake.
Deep basin is the top-rated area: a deep basin in about 45 ft of water that rates prime for cisco (lake herring) in summer. The interactive chart above rates every spot for each species and season.
For cisco (lake herring), 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 McDiarmid 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.
Fanny Lake 1 mi · Fall Lake 1 mi · Mackenzie Lake 2 mi · Simpson Lake 3 mi · Forlise Lake 3 mi · Hartle Lake 3 mi · Expectation Lake 4 mi · Boyce Lake 5 mi · Desperation Lake 5 mi · Lower Redwater Lake 5 mi · Salvation Lake 6 mi · Dennis Lake 7 mi
See how McDiarmid Lake stacks up: best smallmouth bass lakes in Ontario · best walleye lakes in Ontario · best yellow perch lakes in Ontario · best rock bass lakes in Ontario
More water nearby: Nipissing District fishing maps (683 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.