Sign inSign up free Sign inSign up free Sign inSign up freeShared by DepthScout anglers. Exact spots stay private, always.
559-acre lake near Calhoun County. Iowa DNR survey water. The lake tops out around 5 ft. The depth chart is built from real state fisheries GPS surveys, so the humps, channels and drop-offs you see are measured, not guessed. Here is how the season plays out for each species, straight from the data behind the map.
On the chart, South Twin Lake draws 559 acres inside 3.6 miles of shoreline. Nearly circular (index 1.1), so the story is the bottom, not the bank. All of it is shallow-zone water — under ~15 ft across the entire basin, so the food chain has the run of the place. The basin spans about 1.2 mi end to end and 0.9 mi across at its widest. You'll find it in Calhoun County. The nearest mapped water is North Twin Lake, 2 mi to the northeast.
In spring, largemouth bass run shallow here, mostly 1 to 5 ft. Summer keeps them at 2 to 5 ft, and they winter in 2 to 5 ft. Spring largemouth bass concentrate at Shallow bay flat, a prime-rated weed flat around 2 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 | 1 to 5 ft | dawn & dusk | Shallow bay flat (2 ft) | Spinnerbait, Chatterbait |
| Summer | 2 to 5 ft | dawn & dusk | Shallow bay flat (2 ft) | Texas-rigged 10" worm, Deep-diving crankbait |
| Fall | 1 to 5 ft | midday & dawn | Main-lake point (2 ft) | Squarebill crankbait (shad), Spinnerbait |
| Winter | 2 to 5 ft | midday | Break off the point (4 ft) | Blade bait, Jigging spoon |
The spring pattern is a shallow one: bluegill in 1 to 5 ft. The depth story barely changes: 1 to 5 ft through summer, 2 to 5 ft in winter. The spot to know is Shallow bay flat, a weed flat in about 2 ft of water that rates prime for bluegill in spring. Plan around early morning and the evening in the warm months. Summer baits: a small sponge spider (fly) or a micro tube jig gets it done.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 1 to 5 ft | midday & dusk | Shallow bay flat (2 ft) | 1/32 oz jig + micro plastic, Tiny popper (evenings) |
| Summer | 1 to 5 ft | dawn & dusk | Shallow bay flat (2 ft) | Small sponge spider (fly), Micro tube jig |
| Fall | 2 to 5 ft | midday | Shallow bay flat (2 ft) | Micro jig + waxworm, Small spoon tipped |
| Winter | 2 to 5 ft | midday | Deep basin (5 ft) | Tungsten ice jig + plastic, Tiny spoon |
Spring puts crappie in skinny water — 1 to 5 ft is the zone. Summer fish stay in 2 to 5 ft, and winter fish hold in 2 to 5 ft. Deep basin is the standout, a deep basin at roughly 5 ft, rated prime for winter crappie. Plan around early morning and the evening in the warm months. A jig trolled/spider-rigged or a small crankbait (trolled) covers the summer program.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 1 to 5 ft | midday & dawn | Shallow bay flat (2 ft) | 1/16 oz jig + tube, Curly-tail grub |
| Summer | 2 to 5 ft | dawn & dusk | Shallow bay flat (2 ft) | Jig trolled/spider-rigged, Small crankbait (trolled) |
| Fall | 2 to 5 ft | dawn | Shallow bay flat (2 ft) | Jig + minnow combo, Small swimbait (1.5-2") |
| Winter | 2 to 5 ft | midday | Deep basin (5 ft) | Tungsten jig + soft plastic, Tiny jigging spoon |
Spring yellow perch on South Twin Lake hold shallow, usually 1 to 5 ft. Depth-wise the year is flat: 2 to 5 ft in summer, 2 to 5 ft once it turns cold. Put Shallow bay flat first on the milk run — a weed flat near 2 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 | 1 to 5 ft | midday & dawn | Shallow bay flat (2 ft) | Small jig + curly tail, Perch-pattern micro crank |
| Summer | 2 to 5 ft | dawn | Deep basin (5 ft) | Drop-shot micro plastics, Small spoon tipped with worm |
| Fall | 2 to 5 ft | midday | Deep basin (5 ft) | Jigging spoon (small), Perch rig / spreader |
| Winter | 2 to 5 ft | midday & dawn | Deep basin (5 ft) | Tungsten jig + spikes, Rattle spoon (small) |
In spring, channel catfish run shallow here, mostly 1 to 5 ft. Summer keeps them at 2 to 5 ft, and they winter in 2 to 5 ft. Winter channel catfish concentrate at Deep basin, a prime-rated deep basin around 5 ft. Fish it in after dark and the evening and you'll meet the bite.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 1 to 5 ft | dusk | Shallow bay flat (2 ft) | |
| Summer | 2 to 5 ft | night & dusk | Deep basin (5 ft) | |
| Fall | 2 to 5 ft | dusk | Deep basin (5 ft) | |
| Winter | 2 to 5 ft | midday | Deep basin (5 ft) |
Structure-wise the chart holds 6 features, led in depth by Deep basin at roughly 5 ft.
Access data: Iowa DNR — Boat Ramps. Confirm conditions and fees locally before you launch.
Season dates, license requirements, and size and bag limits for Iowa waters are set by the Iowa DNR — and special regulations can apply to South Twin Lake specifically, so confirm the current rules before you fish.
Check the official Iowa fishing regulations →
South Twin Lake is about 5 ft (2 m) deep at its deepest point. The depth chart here comes from real state fisheries GPS surveys, so the contours reflect measured depths.
Anglers target largemouth bass, bluegill, crappie, yellow perch, channel catfish on South Twin Lake. This isn't a survey of the water — none is published for it — but an informed estimate from the species common to the region, narrowed by this water's depth, size and each species' range.
Shallow bay flat is the top-rated area: a weed flat in about 2 ft of water that rates prime for largemouth bass in spring. Every other rated spot, per species and season, is on the map above.
For largemouth bass, 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 South Twin Lake is regulated by the Iowa DNR. Check the official Iowa regulations for current license requirements, season dates, and size and bag limits — special regulations can apply to this specific water.
North Twin Lake 2 mi · Lizard Lake 17 mi · Black Hawk Lake 22 mi · Arrowhead Lake 23 mi · Black Hawk Pits 24 mi · Badger Lake 25 mi · Storm Lake (incl Little Storm Lake) 31 mi · Swan Lake 31 mi · Spring Lake 33 mi · Pickeral Lake 34 mi · Brushy Creek Lake 34 mi · Don Williams Lake 40 mi
See how South Twin Lake stacks up: best largemouth bass lakes in Iowa · best crappie lakes in Iowa · best bluegill lakes in Iowa · best channel catfish lakes in Iowa
Browse all Iowa fishing maps or see every water on DepthScout. Bathymetry credit: state fisheries survey programs. 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.