Sign inSign up free Sign inSign up free Sign inSign up freeLake depth chart
Today's read
Rating depth structure for brook trout.
Recent public catches load as you reach this section.
533-acre lake in Thunder Bay District, Ontario. The lake tops out around 171 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 the Ontario MNRF survey of 1981 (an MNRF lake survey). Here is how the season plays out for each species, straight from the data behind the map.
Big Duck Lake maps at 537 acres behind 7.5 miles of shoreline — one island included. A development index of 2.3 means a maze of bays and points: far more casting targets than a round bowl of the same size. Roughly 34% of the water is 15 ft or less, the band where the food chain lives. End to end it runs roughly 1.8 mi, about 1.4 mi across. It sits in Thunder Bay District. Crosman Lake sits 3 mi southeast — the closest neighbouring chart.
Early season brook trout use the shallows, holding in 2 to 15 ft. Expect a summer slide to 10 to 30 ft, then a winter hold in 3 to 20 ft. Put Secondary point first on the milk run — a point near 10 ft that grades prime for spring. In summer the feeding windows fall in early morning and the evening. Tie on a small spoon fished deep or a trolled lake-clear wobbler + worm and you're in the game.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 2 to 15 ft | dawn & dusk | Secondary point (10 ft) | Small inline spinner (gold), Tiny spoon |
| Summer | 10 to 30 ft | dawn & dusk | open water | Small spoon fished deep, Trolled lake-clear wobbler + worm |
| Fall | 2 to 15 ft | midday & dawn | Secondary point (10 ft) | Small spoon (orange), Spinner |
| Winter | 3 to 20 ft | dawn | Shallow bay flat (3 ft) | Small jigging spoon, Tungsten jig + plastic |
Count 7 structure marks on this chart. The deepest, Deep basin, sits near 148 ft.
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 Big Duck Lake specifically, so confirm the current rules before you fish.
Check the official Ontario fishing regulations →
Big Duck Lake is about 171 ft (52 m) deep at its deepest point. The depth data here comes from the Ontario MNRF survey of 1981 (an MNRF lake survey).
Anglers target brook trout on Big Duck Lake.
Secondary point is the top-rated area: a point in about 10 ft of water that rates prime for brook trout in spring. The map above holds the full rated-spot list for every 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 Big Duck 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.
Crosman Lake 3 mi · Bluff Lake 3 mi · Deep Lake 5 mi · Chapman Lake 6 mi · Ambrose Lake 7 mi · Flicker Lake 8 mi · Ducell Lake 9 mi · Found Lake 9 mi · Davidson Lake 9 mi · Craig Lake 10 mi · Antler Lake 11 mi · Dickison Lake 14 mi
See how Big Duck Lake stacks up: best brook trout lakes in Ontario
More water nearby: Thunder Bay District fishing maps (662 charts). Browse all Ontario fishing maps. 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.