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127,814-acre section. The twin southwest arms: Owen Sound's salmon harbour and Wiarton's Colpoys Bay, one of Ontario's best splake and whitefish waters, with chinook staging off both sounds each fall. The lake tops out around 405 ft. The depth chart is built from real NOAA hydrographic survey soundings, so the humps, channels and drop-offs you see are measured, not guessed. What follows comes from the same scoring engine that paints the spots above.
Traced from the shoreline, Georgian Bay - Owen Sound & Colpoys Bay runs 128,475 acres with 113.4 miles of edge — 3 islands included. With a shoreline index of 2.3, this water is all arms and coves — edge habitat well beyond its acreage. 5% of the surface is littoral (under ~15 ft) — cover, weeds and forage water. End to end it runs roughly 26.1 mi, about 19.4 mi across. You'll find it in Grey County. For a second option, Mary Lake lies 3 mi southwest.
Start shallow in spring: chinook salmon sit in 5 to 40 ft that time of year. Warm water sends them out to 50 to 120 ft; cold water stacks them in 30 to 90 ft. Top water on the chart: Sydenham River mouth (Owen Sound), an inflow / creek mouth in the 4 ft range, prime in spring. Fish it in early morning and the evening and you'll meet the bite. Throw a flasher + fly (green/white) or a magnum spoon on downrigger until the fish tell you otherwise.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 5 to 40 ft | dawn & dusk | Sydenham River mouth (Owen Sound) (4 ft) | Trolled spoon (orange/gold), Stickbait off planer boards |
| Summer | 50 to 120 ft | dawn & dusk | Sharp break (77 ft) | Flasher + fly (green/white), Magnum spoon on downrigger |
| Fall | 10 to 50 ft | dawn & dusk | Sydenham River mouth (Owen Sound) (4 ft) | J-plug (glow), Flasher + fly |
| Winter | 30 to 90 ft | midday | Sharp break (77 ft) | Small spoon on a slow troll, Stickbait deep |
Start shallow in spring: rainbow trout sit in 5 to 20 ft that time of year. Summer pushes them deeper, 8 to 30 ft, and winter fish settle into 8 to 40 ft. The spot to know is Sydenham River mouth (Owen Sound), an inflow / creek mouth in about 4 ft of water that rates prime for rainbow trout in spring. Warm-month bites cluster around early morning and the evening. 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 | Sydenham River mouth (Owen Sound) (4 ft) | Inline spinner (silver), Small spoon |
| Summer | 8 to 30 ft | dawn & dusk | Rock reef (9 ft) | Dodger + spoon (deep troll), Flutter spoon |
| Fall | 10 to 35 ft | dawn & dusk | Rock reef (11 ft) | Casting spoon, Jerkbait over shoals |
| Winter | 8 to 40 ft | dawn | Sharp break (26 ft) | Jigging spoon, Tube jig (white) |
Spring brown trout on Georgian Bay - Owen Sound & Colpoys Bay hold shallow, usually 3 to 25 ft. By summer they slide out to 25 to 60 ft, and by winter most fish are in 5 to 35 ft. The chart's best answer is Sydenham River mouth (Owen Sound) — inflow / creek mouth, 4 ft, prime for spring. Prime time lands in after dark and early morning. The summer box starts with a spoon at the thermocline or a deep stickbait (night).
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 3 to 25 ft | dawn & dusk | Sydenham River mouth (Owen Sound) (4 ft) | Stickbait off planer boards (shallow), Small spoon along mud lines |
| Summer | 25 to 60 ft | night & dawn | Sharp break (26 ft) | Spoon at the thermocline, Deep stickbait (night) |
| Fall | 5 to 30 ft | dusk & dawn | Sydenham River mouth (Owen Sound) (4 ft) | Jerkbait over gravel, Casting spoon |
| Winter | 5 to 35 ft | dawn | Sydenham River mouth (Owen Sound) (4 ft) | Jigging spoon, Small stickbait (slow) |
The spring pattern is a shallow one: lake trout in 10 to 40 ft. Midsummer fish sit out in 50 to 120 ft before dropping to 20 to 80 ft for winter. The spot to know is Rock reef, a rock pile in about 11 ft of water that rates prime for lake trout in fall. Plan around early morning in the warm months. Summer baits: a white tube jig (deep) or a magnum spoon on downrigger gets it done.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 10 to 40 ft | dawn & dusk | Rock reef (11 ft) | Casting spoon over shoals, Jerkbait (shallow) |
| Summer | 50 to 120 ft | dawn | Sharp break (77 ft) | White tube jig (deep), Magnum spoon on downrigger |
| Fall | 10 to 50 ft | dusk & dawn | Rock reef (11 ft) | Heavy casting spoon, Jigging rap over reefs |
| Winter | 20 to 80 ft | dawn | Sharp break (26 ft) | White tube jig, Airplane jig |
Come spring, look for lake whitefish tight to the bank in 15 to 45 ft. They move out to 40 to 90 ft in summer and finish the year down in 25 to 70 ft. If you only fish one area, make it Rock reef: a rock pile around 9 ft that scores prime in fall. Best bite is early morning. A blade bait vertical or a small jigging spoon is the honest summer answer here.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 15 to 45 ft | midday & dawn | Rock reef (12 ft) | Small jig + waxworm, Blade bait (small) |
| Summer | 40 to 90 ft | dawn | Sharp break (77 ft) | Blade bait vertical, Small jigging spoon |
| Fall | 8 to 30 ft | dusk | Rock reef (9 ft) | Small spoon (gold), Jig + plastic larva |
| Winter | 25 to 70 ft | midday & dawn | Sharp break (26 ft) | Jigging spoon + bead chain, Tungsten jig + waxie |
Start shallow in spring: splake sit in 5 to 25 ft that time of year. Warm water sends them out to 25 to 60 ft; cold water stacks them in 10 to 45 ft. Top water on the chart: Sharp break, a drop-off in the 26 ft range, prime in summer. Fish it in early morning and the evening and you'll meet the bite. Throw a trolled spoon at the thermocline or a white tube jig (deep) until the fish tell you otherwise.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 5 to 25 ft | dawn & dusk | Rock reef (9 ft) | Small casting spoon (gold/orange), Inline spinner |
| Summer | 25 to 60 ft | dawn & dusk | Sharp break (26 ft) | Trolled spoon at the thermocline, White tube jig (deep) |
| Fall | 10 to 35 ft | dawn & dusk | Rock reef (11 ft) | Casting spoon, Jerkbait |
| Winter | 10 to 45 ft | dawn | Sharp break (26 ft) | Jigging spoon tipped with minnow head, Small white tube |
Georgian Bay - Owen Sound & Colpoys Bay also holds smallmouth bass (10 to 30 ft in summer), northern pike (8 to 20 ft in summer), yellow perch (10 to 30 ft in summer), common carp (3 to 15 ft in summer). Pick any of them on the map above for rated spots and bait picks.
Count 14 structure marks on this chart. The deepest, Deepest basin, sits near 405 ft.
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 Georgian Bay - Owen Sound & Colpoys Bay specifically, so confirm the current rules before you fish.
Check the official Ontario fishing regulations →
Georgian Bay - Owen Sound & Colpoys Bay is about 405 ft (123 m) deep at its deepest point. The depth chart here comes from real NOAA hydrographic surveys, so the contours reflect measured depths.
Anglers target chinook salmon, rainbow trout, brown trout, lake trout, lake whitefish, splake, smallmouth bass, northern pike, yellow perch, common carp on Georgian Bay - Owen Sound & Colpoys Bay.
Sydenham River mouth (Owen Sound) is the top-rated area: an inflow / creek mouth in about 4 ft of water that rates prime for brown trout in spring. Scroll up to the map for the complete spot list by species and season.
For chinook salmon, 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 Georgian Bay - Owen Sound & Colpoys Bay 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.
Mary Lake 3 mi · Lake Charles 4 mi · Gleason Lake 4 mi · Bass Lake 4 mi · Francis Lake 7 mi · Shepherd Lake 11 mi · Berford Lake 12 mi · Mountain Lake 13 mi · Shallow Lake 13 mi · Sheppard Lake 14 mi · Amabel L. 3 14 mi · Boat Lake 14 mi
See how Georgian Bay - Owen Sound & Colpoys Bay stacks up: best smallmouth bass lakes in Ontario · best northern pike lakes in Ontario · best rainbow trout lakes in Ontario · best yellow perch lakes in Ontario
More water nearby: Grey County fishing maps (47 charts). Browse all Ontario fishing maps or see every water on DepthScout. Bathymetry credit: NOAA hydrographic surveys. 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.