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Rating depth structure for largemouth bass.
Shared by DepthScout anglers. Exact spots stay private, always.
2,073-acre reservoir in Portage County, Wisconsin. The lake tops out around 23 ft. The chart is a model: real shoreline, published maximum depth, interpolated in between. A planning tool, never a navigation product. The rest of this page walks each species through its year, using the map's own scoring.
Drawn out, this is 2,081 acres of water rimmed by 36.3 miles of bank — 8 islands included. A development index of 5.7 means a maze of bays and points: far more casting targets than a round bowl of the same size. Roughly 90% of the water is 15 ft or less as modeled, the band where the food chain lives. End to end it runs roughly 7.9 mi, about 1.5 mi across. You'll find it in Portage County. Closest neighbour on DepthScout: Wisconsin Rapids Flowage, 4 mi southwest of here.
Early season walleye use the shallows, holding in 4 to 15 ft. Expect a summer slide to 7 to 23 ft, then a winter hold in 7 to 23 ft. Put Break off the point first on the milk run — a drop-off near 10 ft that grades prime for fall. In summer the feeding windows fall in the evening and early morning. Tie on a crawler harness on bottom bouncer or a deep crankbait (trolled) and you're in the game.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 4 to 15 ft | dusk & dawn | Main-lake point (8 ft) | 1/8 oz jig + minnow, Hair jig |
| Summer | 7 to 23 ft | dusk & dawn | Break off the point (10 ft) | Crawler harness on bottom bouncer, Deep crankbait (trolled) |
| Fall | 7 to 23 ft | dusk & night | Break off the point (10 ft) | Jigging rap, Jig + big minnow |
| Winter | 7 to 23 ft | dusk & dawn | Deep basin (20 ft) | Jigging spoon + minnow head, Rattle bait |
Spring yellow perch on Biron Flowage hold shallow, usually 3 to 12 ft. They move out to 7 to 23 ft in summer and finish the year down in 7 to 23 ft. Put Shallow bay flat first on the milk run — a weed flat near 3 ft that grades prime for spring. The feeding windows run early morning. The summer box starts with a drop-shot micro plastics or a small spoon tipped with worm.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 3 to 12 ft | midday & dawn | Shallow bay flat (3 ft) | Small jig + curly tail, Perch-pattern micro crank |
| Summer | 7 to 23 ft | dawn | Deep basin (20 ft) | Drop-shot micro plastics, Small spoon tipped with worm |
| Fall | 7 to 23 ft | midday | Deep basin (20 ft) | Jigging spoon (small), Perch rig / spreader |
| Winter | 7 to 23 ft | midday & dawn | Deep basin (20 ft) | Tungsten jig + spikes, Rattle spoon (small) |
Spring puts northern pike in skinny water — 2 to 8 ft is the zone. Warm water sends them out to 8 to 20 ft; cold water stacks them in 5 to 15 ft. Shallow bay flat is the standout, a weed flat at roughly 3 ft, rated prime for spring northern pike. Plan around early morning and the evening in the warm months. A bucktail or a weedless spoon over cabbage covers the summer program.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 2 to 8 ft | midday & dawn | Shallow bay flat (3 ft) | #5 inline spinner, Spoon (red/white) |
| Summer | 8 to 20 ft | dawn & dusk | Break off the point (10 ft) | Bucktail, Weedless spoon over cabbage |
| Fall | 6 to 18 ft | midday & dawn | Break off the point (10 ft) | Big rubber (Bull Dawg style), Husky-style jerkbait |
| Winter | 5 to 15 ft | midday | Shallow bay flat (3 ft) | Tip-ups, Large jigging spoon |
The spring pattern is a shallow one: muskellunge in 3 to 12 ft. Midsummer fish sit out in 7 to 23 ft before dropping to 7 to 23 ft for winter. The spot to know is Break off the point, a drop-off in about 10 ft of water that rates prime for muskellunge in fall. Plan around the evening and early morning in the warm months. Summer baits: a double-10 bucktail or a topwater (walk-the-dog / creeper) gets it done.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 3 to 12 ft | dusk | Shallow bay flat (3 ft) | Smaller bucktail (#8 blades), 6" glide bait |
| Summer | 7 to 23 ft | dusk & dawn | Main-lake point (8 ft) | Double-10 bucktail, Topwater (walk-the-dog / creeper) |
| Fall | 6 to 23 ft | midday & dusk | Break off the point (10 ft) | Big rubber (Bull Dawg style), 10"+ glide bait |
| Winter | 7 to 23 ft | midday | Deep basin (20 ft) | Large rubber, crawled slow |
Spring puts smallmouth bass in skinny water — 3 to 12 ft is the zone. Warm water sends them out to 7 to 23 ft; cold water stacks them in 7 to 23 ft. Main-lake point is the standout, a point at roughly 8 ft, rated prime for fall smallmouth bass. Plan around early morning and the evening in the warm months. A drop shot (goby/minnow) or a ned rig covers the summer program.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 3 to 12 ft | dawn & dusk | Main-lake point (8 ft) | Ned rig, Tube jig |
| Summer | 7 to 23 ft | dawn & dusk | Break off the point (10 ft) | Drop shot (goby/minnow), Ned rig |
| Fall | 7 to 23 ft | midday & dawn | Main-lake point (8 ft) | Jerkbait, Blade bait |
| Winter | 7 to 23 ft | midday | Break off the point (10 ft) | Blade bait, Hair jig |
In spring, largemouth bass run shallow here, mostly 2 to 10 ft. Midsummer fish sit out in 8 to 20 ft before dropping to 7 to 23 ft for winter. Spring largemouth bass concentrate at Shallow bay flat, a prime-rated weed flat around 3 ft. Fish it in early morning and the evening and you'll meet the bite. You won't need more than a texas-rigged 10" worm or a deep-diving crankbait most summer days.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 2 to 10 ft | dawn & dusk | Shallow bay flat (3 ft) | Spinnerbait, Chatterbait |
| Summer | 8 to 20 ft | dawn & dusk | Break off the point (10 ft) | Texas-rigged 10" worm, Deep-diving crankbait |
| Fall | 4 to 15 ft | midday & dawn | Main-lake point (8 ft) | Squarebill crankbait (shad), Spinnerbait |
| Winter | 7 to 23 ft | midday | Break off the point (10 ft) | Blade bait, Jigging spoon |
Biron Flowage also holds crappie (7 to 23 ft in summer), bluegill (4 to 15 ft in summer), channel catfish (7 to 23 ft in summer), flathead catfish (6 to 23 ft in summer), lake sturgeon (7 to 23 ft in summer). Pick any of them on the map above for rated spots and bait picks.
Count 6 structure marks on this chart. The deepest, Deep basin, sits near 20 ft.
Access data: Wisconsin DNR - Boat Access Sites, Shore Fishing Sites, and DNR Parking Lots. Confirm conditions and fees locally before you launch.
Season dates, license requirements, and size and bag limits for Wisconsin waters are set by the Wisconsin DNR — and special regulations can apply to Biron Flowage specifically, so confirm the current rules before you fish.
Check the official Wisconsin fishing regulations →
Biron Flowage is about 23 ft (7 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 walleye, yellow perch, northern pike, muskellunge, smallmouth bass, largemouth bass, crappie, bluegill, channel catfish, flathead catfish, lake sturgeon on Biron Flowage. These come from the Wisconsin DNR's per-lake fish listing; where the DNR lists a group (panfish, catfish, trout) the specific species are resolved from Wisconsin's fish distribution by the lake's location, depth and habitat.
Break off the point is the top-rated area: a drop-off in about 10 ft of water that rates prime for walleye in fall. The map above holds the full rated-spot list for every species and season.
For walleye, the summer bite is best in the evening and 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 Biron Flowage is regulated by the Wisconsin DNR. Check the official Wisconsin regulations for current license requirements, season dates, and size and bag limits — special regulations can apply to this specific water.
Wisconsin Rapids Flowage 4 mi · Wazeecha Lake* 6 mi · Nepco Lake 8 mi · Wisconsin R Fl C3-Stevens Pt 9 mi · Springville Pond 10 mi · McDill Pond 10 mi · Ross Lake 14 mi · Anderson Lake 14 mi · Jordan Pond 15 mi · Van Order Pond (Christensen) 16 mi · Camelot Lake 17 mi · Arrowhead Lake (Manchester) 17 mi
See how Biron Flowage stacks up: best largemouth bass lakes in Wisconsin · best smallmouth bass lakes in Wisconsin · best walleye lakes in Wisconsin · best northern pike lakes in Wisconsin
More water nearby: Portage County fishing maps (48 charts). Browse all Wisconsin 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.