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11-acre lake in Renfrew County, Ontario. The lake tops out around 37 ft. The depth chart comes from Ontario Ministry of Natural Resources and Forestry bathymetric survey data, so the contours are survey-derived rather than computer-modeled. The depth data here comes from a transect sounding survey by the Ontario MNRF. Every species below gets its seasonal read from the same numbers driving the chart.
On the chart, O'Brien Lake draws 11 acres inside 0.5 miles of shoreline. Nearly circular (index 1.1), so the story is the bottom, not the bank. Roughly 79% of the water is 15 ft or less, the band where the food chain lives. The water lies in Renfrew County. Closest neighbour on DepthScout: Little Garvin Lake, 1 mi southeast of here.
The spring pattern is a shallow one: brook trout in 2 to 15 ft. Midsummer fish sit out in 10 to 30 ft before dropping to 3 to 20 ft for winter. The spot to know is Deep basin, a deep basin in about 29 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 | Shallow bay flat (3 ft) | Small inline spinner (gold), Tiny spoon |
| Summer | 10 to 30 ft | dawn & dusk | Deep basin (29 ft) | Small spoon fished deep, Trolled lake-clear wobbler + worm |
| Fall | 2 to 15 ft | midday & dawn | open water | Small spoon (orange), Spinner |
| Winter | 3 to 20 ft | dawn | Shoreline break (4 ft) | Small jigging spoon, Tungsten jig + plastic |
Start shallow in spring: rainbow trout sit in 5 to 20 ft that time of year. Warm water sends them out to 8 to 30 ft; cold water stacks them in 7 to 37 ft. Top water on the chart: Deep basin, a deep basin in the 29 ft range, prime in winter. Fish it in early morning and the evening and you'll meet the bite. Throw a dodger + spoon (deep troll) or a flutter spoon until the fish tell you otherwise.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 5 to 20 ft | dawn & dusk | Shoreline break (4 ft) | Inline spinner (silver), Small spoon |
| Summer | 8 to 30 ft | dawn & dusk | Deep basin (29 ft) | Dodger + spoon (deep troll), Flutter spoon |
| Fall | 10 to 35 ft | dawn & dusk | Deep basin (29 ft) | Casting spoon, Jerkbait over shoals |
| Winter | 7 to 37 ft | dawn | Deep basin (29 ft) | Jigging spoon, Tube jig (white) |
O'Brien Lake carries 3 mapped structure features, topping out (or rather bottoming out) at Deep basin, about 29 ft down.
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 37 ft (11 m) deep at its deepest point. The depth data here comes from a transect sounding survey by the Ontario MNRF.
Anglers target brook trout, rainbow trout on O'Brien Lake.
Deep basin is the top-rated area: a deep basin in about 29 ft of water that rates prime for brook trout in summer. Scroll up to the map for the complete spot list by 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 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.
Little Garvin Lake 1 mi · Donahue Long Lake 1 mi · Garvin Lake 1 mi · Archies Lake 1 mi · Hardwood Lake 2 mi · Crutch Lake 2 mi · Burns Long Lake 3 mi · Burns Lake 3 mi · Schavens Lake 4 mi · Wolf Lake 4 mi · Highland Lake 4 mi · Dugan Lake 4 mi
See how O'Brien Lake stacks up: best rainbow trout lakes in Ontario · best brook trout lakes in Ontario
More water nearby: Renfrew County fishing maps (298 charts). Browse all Ontario fishing maps or see every water on DepthScout. Bathymetry: published agency survey data. 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.