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87-acre lake in Lanark County, 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. Here's the year, species by species, as the scoring engine sees it.
O'Brien Lake maps at 88 acres behind 3.2 miles of shoreline. A development index of 2.4 means a maze of bays and points: far more casting targets than a round bowl of the same size. About 71% of the surface sits shallower than 15 ft on the modeled chart — that's the weed-and-bait zone. Call it 1.1 mi long by 0.3 mi wide at the broadest reach. Lanark County claims this one. Farren Lake sits 1 mi southwest — the closest neighbouring chart.
Early season rainbow trout use the shallows, holding in 5 to 20 ft. Summer is an 8 to 30 ft game here, winter an 8 to 40 ft one. The chart's best answer is Break off the point — drop-off, 25 ft, prime for winter. Best bite is early morning and the evening. Tie on a dodger + spoon (deep troll) or a flutter spoon and you're in the game.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 5 to 20 ft | dawn & dusk | Main-lake point (14 ft) | Inline spinner (silver), Small spoon |
| Summer | 8 to 30 ft | dawn & dusk | Break off the point (25 ft) | Dodger + spoon (deep troll), Flutter spoon |
| Fall | 10 to 35 ft | dawn & dusk | Main-lake point (14 ft) | Casting spoon, Jerkbait over shoals |
| Winter | 8 to 40 ft | dawn | Break off the point (25 ft) | Jigging spoon, Tube jig (white) |
Start shallow in spring: yellow perch sit in 3 to 12 ft that time of year. Summer pushes them deeper, 10 to 30 ft, and winter fish settle into 15 to 35 ft. The spot to know is Shallow bay flat, a weed flat in about 6 ft of water that rates prime for yellow perch in spring. Warm-month bites cluster around early morning. Throw a drop-shot micro plastics or a small spoon tipped with worm until the fish tell you otherwise.
| 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) |
Come spring, look for northern pike tight to the bank in 2 to 8 ft. Expect a summer slide to 8 to 20 ft, then a winter hold in 5 to 15 ft. Start at Shallow bay flat. It's a weed flat holding about 6 ft of water and rates prime come spring. Prime time lands in early morning and the evening. A bucktail or a weedless spoon over cabbage is the honest summer answer here.
| 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 |
Come spring, look for smallmouth bass tight to the bank in 3 to 12 ft. Expect a summer slide to 10 to 30 ft, then a winter hold in 20 to 45 ft. Start at Main-lake point. It's a point holding about 14 ft of water and rates prime come fall. Prime time lands in early morning and the evening. A drop shot (goby/minnow) or a ned rig is the honest summer answer here.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 3 to 12 ft | dawn & dusk | Main-lake point (14 ft) | Ned rig, Tube jig |
| Summer | 10 to 30 ft | dawn & dusk | Break off the point (25 ft) | Drop shot (goby/minnow), Ned rig |
| Fall | 8 to 25 ft | midday & dawn | Main-lake point (14 ft) | Jerkbait, Blade bait |
| Winter | 20 to 45 ft | midday | Break off the point (25 ft) | Blade bait, Hair jig |
When the water first warms, largemouth bass slide up into 2 to 10 ft. By summer they slide out to 8 to 20 ft, and by winter most fish are in 15 to 35 ft. If you only fish one area, make it Shallow bay flat: a weed flat around 6 ft that scores prime in spring. In summer the feeding windows fall in early morning and the evening. Keep a texas-rigged 10" worm or a deep-diving crankbait rigged through the warm months.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 2 to 10 ft | dawn & dusk | Shallow bay flat (6 ft) | Spinnerbait, Chatterbait |
| Summer | 8 to 20 ft | dawn & dusk | Main-lake point (14 ft) | Texas-rigged 10" worm, Deep-diving crankbait |
| Fall | 4 to 15 ft | midday & dawn | Main-lake point (14 ft) | Squarebill crankbait (shad), Spinnerbait |
| Winter | 15 to 35 ft | midday | Break off the point (25 ft) | Blade bait, Jigging spoon |
The spring pattern is a shallow one: rock bass in 2 to 10 ft. Midsummer fish sit out in 5 to 20 ft before dropping to 12 to 30 ft for winter. The spot to know is Main-lake point, a point in about 14 ft of water that rates prime for rock bass in summer. Plan around the evening in the warm months. Summer baits: a ned rig (small) or a marabou jig gets it done.
| 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 |
O'Brien Lake also holds 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.
O'Brien Lake carries 6 mapped structure features, topping out (or rather bottoming out) at Deep basin, about 47 ft down.
Access data: Geospatial Ontario - Fishing Access Points. 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 O'Brien Lake specifically, so confirm the current rules before you fish.
Check the official Ontario fishing regulations →
O'Brien Lake 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 rainbow trout, yellow perch, northern pike, smallmouth bass, largemouth bass, rock bass, bluegill, pumpkinseed, brown bullhead on O'Brien Lake.
Shallow bay flat is the top-rated area: a weed flat in about 6 ft of water that rates prime for yellow perch in spring. Scroll up to the map for the complete spot list by species and season.
For rainbow 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 O'Brien 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.
Farren Lake 1 mi · Crosby Lake 2 mi · Christie Lake 3 mi · Little Silver Lake 3 mi · Rainbow Lake 3 mi · Little Crosby Lake 4 mi · Tommy Lake 4 mi · Lake of the Hills 4 mi · McGowan Lake 5 mi · Spectacle Lake 5 mi · Rock Lake 5 mi · Grady Lake 5 mi
See how O'Brien Lake stacks up: best largemouth bass lakes in Ontario · best smallmouth bass lakes in Ontario · best northern pike lakes in Ontario · best bluegill lakes in Ontario
More water nearby: Lanark County fishing maps (74 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.