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Rating depth structure for largemouth bass.
Shared by DepthScout anglers. Exact spots stay private, always.
205-acre reservoir in Lincoln County, Wisconsin. The lake tops out around 22 ft. Depth here is modeled from the true shoreline and max depth rather than surveyed; use it to plan, not to navigate. Here is how the season plays out for each species, straight from the data behind the map.
Grandmother Flowage maps at 205 acres behind 4.5 miles of shoreline. That shoreline is heavily fingered (development index 2.2) — bays, points and pockets everywhere, which multiplies the fishable edge. 92% of the surface is littoral (under ~15 ft), per the model — cover, weeds and forage water. End to end it runs roughly 1.9 mi, about 0.4 mi across. Lincoln County claims this one. If the bite dies, Grandfather Flowage is 4 mi to the southwest.
Start shallow in spring: walleye sit in 4 to 15 ft that time of year. Summer pushes them deeper, 7 to 22 ft, and winter fish settle into 7 to 22 ft. The spot to know is Deep basin, a deep basin in about 19 ft of water that rates prime for walleye in winter. Warm-month bites cluster around the evening and early morning. Throw a crawler harness on bottom bouncer or a deep crankbait (trolled) until the fish tell you otherwise.
| 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 22 ft | dusk & dawn | Main-lake point (8 ft) | Crawler harness on bottom bouncer, Deep crankbait (trolled) |
| Fall | 7 to 22 ft | dusk & night | Main-lake point (8 ft) | Jigging rap, Jig + big minnow |
| Winter | 7 to 22 ft | dusk & dawn | Deep basin (19 ft) | Jigging spoon + minnow head, Rattle bait |
Spring puts yellow perch in skinny water — 3 to 12 ft is the zone. As the season builds they drop to 7 to 22 ft, wintering in 7 to 22 ft. Spring yellow perch concentrate at Shallow bay flat, a prime-rated weed flat around 3 ft. Warm-month bites cluster around early morning. A drop-shot micro plastics or a small spoon tipped with worm covers the summer program.
| 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 22 ft | dawn | Deep basin (19 ft) | Drop-shot micro plastics, Small spoon tipped with worm |
| Fall | 7 to 22 ft | midday | Deep basin (19 ft) | Jigging spoon (small), Perch rig / spreader |
| Winter | 7 to 22 ft | midday & dawn | Deep basin (19 ft) | Tungsten jig + spikes, Rattle spoon (small) |
Spring northern pike on Grandmother Flowage hold shallow, usually 2 to 8 ft. By summer they slide out to 8 to 20 ft, and by winter most fish are in 5 to 15 ft. The chart's best answer is Shallow bay flat — weed flat, 3 ft, prime for spring. Prime time lands in early morning and the evening. The summer box starts with a bucktail or a weedless spoon over cabbage.
| 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 | Main-lake point (8 ft) | Bucktail, Weedless spoon over cabbage |
| Fall | 6 to 18 ft | midday & dawn | Main-lake point (8 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 |
Spring muskellunge on Grandmother Flowage hold shallow, usually 3 to 12 ft. They move out to 7 to 22 ft in summer and finish the year down in 7 to 22 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 the evening and early morning. The summer box starts with a double-10 bucktail or a topwater (walk-the-dog / creeper).
| 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 22 ft | dusk & dawn | Main-lake point (8 ft) | Double-10 bucktail, Topwater (walk-the-dog / creeper) |
| Fall | 6 to 22 ft | midday & dusk | Main-lake point (8 ft) | Big rubber (Bull Dawg style), 10"+ glide bait |
| Winter | 7 to 22 ft | midday | Deep basin (19 ft) | Large rubber, crawled slow |
Spring smallmouth bass on Grandmother Flowage hold shallow, usually 3 to 12 ft. By summer they slide out to 7 to 22 ft, and by winter most fish are in 7 to 22 ft. The chart's best answer is Main-lake point — point, 8 ft, prime for fall. Prime time lands in early morning and the evening. The summer box starts with a drop shot (goby/minnow) or a ned rig.
| 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 22 ft | dawn & dusk | Main-lake point (8 ft) | Drop shot (goby/minnow), Ned rig |
| Fall | 7 to 22 ft | midday & dawn | Main-lake point (8 ft) | Jerkbait, Blade bait |
| Winter | 7 to 22 ft | midday | Deep basin (19 ft) | Blade bait, Hair jig |
Early season largemouth bass use the shallows, holding in 2 to 10 ft. Expect a summer slide to 8 to 20 ft, then a winter hold in 7 to 22 ft. Put Shallow bay flat first on the milk run — a weed flat near 3 ft that grades prime for spring. In summer the feeding windows fall in early morning and the evening. Tie on a texas-rigged 10" worm or a deep-diving crankbait and you're in the game.
| 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 | Main-lake point (8 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 22 ft | midday | Deep basin (19 ft) | Blade bait, Jigging spoon |
Grandmother Flowage also holds crappie (7 to 22 ft in summer), bluegill (4 to 15 ft in summer), pumpkinseed (2 to 10 ft in summer). Pick any of them on the map above for rated spots and bait picks.
Grandmother Flowage carries 5 mapped structure features, topping out (or rather bottoming out) at Deep basin, about 19 ft down.
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 Grandmother Flowage specifically, so confirm the current rules before you fish.
Check the official Wisconsin fishing regulations →
Grandmother Flowage is about 22 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, pumpkinseed on Grandmother 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.
Deep basin is the top-rated area: a deep basin in about 19 ft of water that rates prime for walleye in winter. 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 Grandmother 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.
Grandfather Flowage 4 mi · Road Lake 4 mi · Skanawan Lake 5 mi · LaCerte Lake 5 mi · Silver Lake 5 mi · Kaise Lake 5 mi · Beaver Lake 5 mi · Tug Lake 5 mi · Olivotti Lake 5 mi · Spirit River Flowage 6 mi · Lake Mohawksin 6 mi · Larson Lake 6 mi
See how Grandmother 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: Lincoln County fishing maps (91 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.