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14-acre lake near Union County. The lake tops out around 12 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. What the data behind the map says about each species, season by season:
The outline encloses 14 acres, worked by 0.6 miles of shoreline. The basin is a simple one (shoreline index 1.2) — close to a bowl, so the structure on the chart matters more than the bank. Every acre of it sits shallower than ~15 ft: one big littoral zone, cover and forage throughout. Call it 0.3 mi long. It sits in Union County. If the bite dies, Three Mile Lake is 10 mi to the northwest.
Come spring, look for crappie tight to the bank in 2 to 8 ft. They move out to 4 to 12 ft in summer and finish the year down in 4 to 12 ft. If you only fish one area, make it Deep basin: a deep basin around 12 ft that scores prime in winter. Best bite is early morning and the evening. A jig trolled/spider-rigged or a small crankbait (trolled) is the honest summer answer here.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 2 to 8 ft | midday & dawn | Shallow bay flat (2 ft) | 1/16 oz jig + tube, Curly-tail grub |
| Summer | 4 to 12 ft | dawn & dusk | Break off the point (12 ft) | Jig trolled/spider-rigged, Small crankbait (trolled) |
| Fall | 4 to 12 ft | dawn | Break off the point (12 ft) | Jig + minnow combo, Small swimbait (1.5-2") |
| Winter | 4 to 12 ft | midday | Deep basin (12 ft) | Tungsten jig + soft plastic, Tiny jigging spoon |
When the water first warms, bluegill slide up into 1 to 6 ft. By summer they slide out to 3 to 12 ft, and by winter most fish are in 4 to 12 ft. If you only fish one area, make it Shallow bay flat: a weed flat around 2 ft that scores prime in spring. In summer the feeding windows fall in early morning and the evening. Keep a small sponge spider (fly) or a micro tube jig rigged through the warm months.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 1 to 6 ft | midday & dusk | Shallow bay flat (2 ft) | 1/32 oz jig + micro plastic, Tiny popper (evenings) |
| Summer | 3 to 12 ft | dawn & dusk | Shallow bay flat (2 ft) | Small sponge spider (fly), Micro tube jig |
| Fall | 4 to 12 ft | midday | Break off the point (12 ft) | Micro jig + waxworm, Small spoon tipped |
| Winter | 4 to 12 ft | midday | Deep basin (12 ft) | Tungsten ice jig + plastic, Tiny spoon |
When the water first warms, largemouth bass slide up into 2 to 10 ft. Summer is a 4 to 12 ft game here, winter a 4 to 12 ft one. Start at Shallow bay flat. It's a weed flat holding about 2 ft of water and rates prime come spring. The feeding windows run early morning and the evening. Keep a texas-rigged 10" worm or a deep-diving crankbait rigged through the warm months.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 2 to 10 ft | dawn & dusk | Shallow bay flat (2 ft) | Spinnerbait, Chatterbait |
| Summer | 4 to 12 ft | dawn & dusk | Break off the point (12 ft) | Texas-rigged 10" worm, Deep-diving crankbait |
| Fall | 3 to 12 ft | midday & dawn | Main-lake point (5 ft) | Squarebill crankbait (shad), Spinnerbait |
| Winter | 4 to 12 ft | midday | Break off the point (12 ft) | Blade bait, Jigging spoon |
When the water first warms, channel catfish slide up into 3 to 12 ft. There's no big seasonal slide here — summer means 4 to 12 ft, winter 4 to 12 ft. Start at Deep basin. It's a deep basin holding about 12 ft of water and rates prime come winter. The feeding windows run after dark and the evening.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 3 to 12 ft | dusk | Shallow bay flat (2 ft) | |
| Summer | 4 to 12 ft | night & dusk | Deep basin (12 ft) | |
| Fall | 4 to 12 ft | dusk | Deep basin (12 ft) | |
| Winter | 4 to 12 ft | midday | Deep basin (12 ft) |
Start shallow in spring: yellow perch sit in 3 to 12 ft that time of year. They don't go far with the seasons — 4 to 12 ft covers summer, 4 to 12 ft covers winter. Top water on the chart: Deep basin, a deep basin in the 12 ft range, prime in fall. Fish it in early morning and you'll meet the bite. Throw a drop-shot micro plastics or a small spoon tipped with worm until the fish tell you otherwise.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 3 to 12 ft | midday & dawn | Shallow bay flat (2 ft) | Small jig + curly tail, Perch-pattern micro crank |
| Summer | 4 to 12 ft | dawn | Deep basin (12 ft) | Drop-shot micro plastics, Small spoon tipped with worm |
| Fall | 4 to 12 ft | midday | Deep basin (12 ft) | Jigging spoon (small), Perch rig / spreader |
| Winter | 4 to 12 ft | midday & dawn | Deep basin (12 ft) | Tungsten jig + spikes, Rattle spoon (small) |
Spring puts walleye in skinny water — 3 to 12 ft is the zone. Summer fish stay in 4 to 12 ft, and winter fish hold in 4 to 12 ft. Break off the point is the standout, a drop-off at roughly 12 ft, rated prime for fall walleye. Plan around the evening and early morning in the warm months. A crawler harness on bottom bouncer or a deep crankbait (trolled) covers the summer program.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 3 to 12 ft | dusk & dawn | Main-lake point (5 ft) | 1/8 oz jig + minnow, Hair jig |
| Summer | 4 to 12 ft | dusk & dawn | Break off the point (12 ft) | Crawler harness on bottom bouncer, Deep crankbait (trolled) |
| Fall | 4 to 12 ft | dusk & night | Break off the point (12 ft) | Jigging rap, Jig + big minnow |
| Winter | 4 to 12 ft | dusk & dawn | Deep basin (12 ft) | Jigging spoon + minnow head, Rattle bait |
Count 4 structure marks on this chart. The deepest, Deep basin, sits near 12 ft.
Season dates, license requirements, and size and bag limits for Iowa waters are set by the Iowa DNR — and special regulations can apply to Thayer Lake specifically, so confirm the current rules before you fish.
Check the official Iowa fishing regulations →
Thayer Lake is about 12 ft (4 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 crappie, bluegill, largemouth bass, channel catfish, yellow perch, walleye on Thayer 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.
Deep basin is the top-rated area: a deep basin in about 12 ft of water that rates prime for crappie in winter. Every other rated spot, per species and season, is on the map above.
For crappie, 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 Thayer 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.
Three Mile Lake 10 mi · Twelve Mile Creek Lake 11 mi · West Lake (Osceola) 13 mi · Hurley Creek Pond 16 mi · McKinley Lake 17 mi · East Lake (Osceola) 17 mi · Summit Lake 17 mi · Green Valley Lake 18 mi · Fogle Lake S.W.A. 21 mi · Loch Ayr 21 mi · Mt. Ayr Old Reservoir 22 mi · Orient Lake 23 mi
See how Thayer Lake stacks up: best largemouth bass lakes in Iowa · best walleye lakes in Iowa · best crappie lakes in Iowa · best bluegill lakes in Iowa
More water nearby: Union County fishing maps (7 charts). 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.