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1,621-acre lake in Frontenac County, Ontario. The lake tops out around 110 ft. The depth data here comes from the Ontario MNRF survey of 1967, a decades-old survey (a transect sounding survey). Here is how the season plays out for each species, straight from the data behind the map.
On the chart, Sydenham Lake draws 1,601 acres inside 37.3 miles of shoreline, broken up by 72 islands. That shoreline is heavily fingered (development index 6.7) — bays, points and pockets everywhere, which multiplies the fishable edge. About 55% of the surface sits shallower than 15 ft — that's the weed-and-bait zone. The basin spans about 3.8 mi end to end and 2.5 mi across at its widest. You'll find it in Frontenac County. For a second option, Cronk Lake lies 2 mi north.
Come spring, look for cisco (lake herring) tight to the bank in 10 to 40 ft. They move out to 40 to 80 ft in summer and finish the year down in 20 to 60 ft. If you only fish one area, make it Break off the point: a drop-off around 61 ft that scores prime in winter. Best bite is 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 (110 ft) | Small silver spoon, Tiny swim jig (white) |
| Summer | 40 to 80 ft | dawn | Break off the point (61 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 | Break off the point (61 ft) | Small jigging spoon (glow/silver), Tungsten jig + minnow head |
Early season yellow perch use the shallows, holding in 3 to 12 ft. Summer is a 10 to 30 ft game here, winter a 15 to 35 ft one. The chart's best answer is Shallow bay flat — weed flat, 5 ft, prime for spring. Best bite is 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 (5 ft) | Small jig + curly tail, Perch-pattern micro crank |
| Summer | 10 to 30 ft | dawn | Shallow feeding flat (16 ft) | Drop-shot micro plastics, Small spoon tipped with worm |
| Fall | 12 to 35 ft | midday | Deep basin (110 ft) | Jigging spoon (small), Perch rig / spreader |
| Winter | 15 to 35 ft | midday & dawn | Shallow feeding flat (16 ft) | Tungsten jig + spikes, Rattle spoon (small) |
In spring, northern pike run shallow here, mostly 2 to 8 ft. Midsummer fish sit out in 8 to 20 ft before dropping to 5 to 15 ft for winter. Spring northern pike concentrate at Shallow bay flat, a prime-rated weed flat around 5 ft. Fish it in early morning and the evening and you'll meet the bite. 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 (5 ft) | #5 inline spinner, Spoon (red/white) |
| Summer | 8 to 20 ft | dawn & dusk | Shallow feeding flat (16 ft) | Bucktail, Weedless spoon over cabbage |
| Fall | 6 to 18 ft | midday & dawn | Shallow bay flat (5 ft) | Big rubber (Bull Dawg style), Husky-style jerkbait |
| Winter | 5 to 15 ft | midday | Shallow bay flat (5 ft) | Tip-ups, Large jigging spoon |
In spring, smallmouth bass run shallow here, mostly 3 to 12 ft. Midsummer fish sit out in 10 to 30 ft before dropping to 20 to 45 ft for winter. Fall smallmouth bass concentrate at Main-lake point, a prime-rated point around 24 ft. Fish it in early morning and the evening and you'll meet the bite. 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 | Secondary point (16 ft) | Ned rig, Tube jig |
| Summer | 10 to 30 ft | dawn & dusk | Main-lake point (24 ft) | Drop shot (goby/minnow), Ned rig |
| Fall | 8 to 25 ft | midday & dawn | Main-lake point (24 ft) | Jerkbait, Blade bait |
| Winter | 20 to 45 ft | midday | Break off the point (61 ft) | Blade bait, Hair jig |
Spring puts largemouth bass in skinny water — 2 to 10 ft is the zone. Warm water sends them out to 8 to 20 ft; cold water stacks them in 15 to 35 ft. Shallow bay flat is the standout, a weed flat at roughly 5 ft, rated prime for spring largemouth bass. Plan around early morning and the evening in the warm months. A texas-rigged 10" worm or a deep-diving crankbait covers the summer program.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 2 to 10 ft | dawn & dusk | Shallow bay flat (5 ft) | Spinnerbait, Chatterbait |
| Summer | 8 to 20 ft | dawn & dusk | Secondary point (16 ft) | Texas-rigged 10" worm, Deep-diving crankbait |
| Fall | 4 to 15 ft | midday & dawn | Secondary point (16 ft) | Squarebill crankbait (shad), Spinnerbait |
| Winter | 15 to 35 ft | midday | Break off the point (61 ft) | Blade bait, Jigging spoon |
Come spring, look for rock bass tight to the bank in 2 to 10 ft. They move out to 5 to 20 ft in summer and finish the year down in 12 to 30 ft. If you only fish one area, make it Secondary point: a point around 16 ft that scores prime in summer. Best bite is 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 | Dock / pier line (4 ft) | 1/16 oz jig + grub, Small inline spinner |
| Summer | 5 to 20 ft | dusk | Secondary point (16 ft) | Ned rig (small), Marabou jig |
| Fall | 8 to 22 ft | midday | Secondary point (16 ft) | Small tube jig, Inline spinner |
| Winter | 12 to 30 ft | midday | Deep basin (110 ft) | Tungsten jig + plastic, Small spoon + spike |
Sydenham Lake also holds crappie (10 to 25 ft in summer), bluegill (4 to 15 ft in summer), pumpkinseed (2 to 10 ft in summer), brown bullhead (3 to 12 ft in summer). Pick any of them on the map above for rated spots and bait picks.
Sydenham Lake carries 9 mapped structure features, topping out (or rather bottoming out) at Deep basin, about 110 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 Sydenham Lake specifically, so confirm the current rules before you fish.
Check the official Ontario fishing regulations →
Sydenham Lake is about 110 ft (34 m) deep at its deepest point. The depth data here comes from the Ontario MNRF survey of 1967, a decades-old survey (a transect sounding survey).
Anglers target cisco (lake herring), yellow perch, northern pike, smallmouth bass, largemouth bass, rock bass, crappie, bluegill, pumpkinseed, brown bullhead on Sydenham Lake.
Shallow bay flat is the top-rated area: a weed flat in about 5 ft of water that rates prime for yellow perch in spring. Open the map above to see every rated 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 Sydenham 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.
Cronk Lake 2 mi · Mica Lake 2 mi · Little Devil Lake 3 mi · Knowlton Lake 3 mi · Gould Lake 3 mi · Blue Lake 3 mi · Draper Lake 4 mi · Pearkes Lake 4 mi · South Otter Lake 5 mi · Loughborough Lake 5 mi · Doe Lake 5 mi · North Otter Lake 5 mi
See how Sydenham Lake stacks up: best largemouth bass lakes in Ontario · best smallmouth bass lakes in Ontario · best northern pike lakes in Ontario · best crappie 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.