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138-acre lake near Tama County. Iowa DNR survey water. 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 138 acres, worked by 2 miles of shoreline. A shoreline index of 1.2 says round and simple: fish relate to depth changes here, not shoreline features. Every acre of it sits shallower than ~15 ft: one big littoral zone, cover and forage throughout. End to end it runs roughly 0.8 mi, about 0.4 mi across. It sits in Tama County. Otter Creek Lake sits 12 mi southeast — the closest neighbouring chart.
Early season largemouth bass use the shallows, holding in 2 to 10 ft. Summer is a 4 to 12 ft game here, winter a 4 to 12 ft one. The chart's best answer is Shallow bay flat — weed flat, 2 ft, prime for spring. Best bite is 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 (2 ft) | Spinnerbait, Chatterbait |
| Summer | 4 to 12 ft | dawn & dusk | Back-bay flat (4 ft) | Texas-rigged 10" worm, Deep-diving crankbait |
| Fall | 3 to 12 ft | midday & dawn | Secondary point (5 ft) | Squarebill crankbait (shad), Spinnerbait |
| Winter | 4 to 12 ft | midday | Break off the point (5 ft) | Blade bait, Jigging spoon |
Spring bluegill on Union Grove Lake hold shallow, usually 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. The chart's best answer is Shallow bay flat — weed flat, 2 ft, prime for spring. Prime time lands in early morning and the evening. The summer box starts with a small sponge spider (fly) or a micro tube jig.
| 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 | Back-bay flat (4 ft) | Small sponge spider (fly), Micro tube jig |
| Fall | 4 to 12 ft | midday | Back-bay flat (4 ft) | Micro jig + waxworm, Small spoon tipped |
| Winter | 4 to 12 ft | midday | Deep basin (12 ft) | Tungsten ice jig + plastic, Tiny spoon |
Spring crappie on Union Grove Lake hold shallow, usually 2 to 8 ft. They move out to 4 to 12 ft in summer and finish the year down in 4 to 12 ft. Put Deep basin first on the milk run — a deep basin near 12 ft that grades prime for winter. The feeding windows run early morning and the evening. The summer box starts with a jig trolled/spider-rigged or a small crankbait (trolled).
| 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 | Back-bay flat (4 ft) | Jig trolled/spider-rigged, Small crankbait (trolled) |
| Fall | 4 to 12 ft | dawn | Back-bay flat (4 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 |
Spring puts yellow perch 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. Back-bay flat is the standout, a weed flat at roughly 4 ft, rated prime for spring yellow perch. Plan around early morning in the warm months. 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 | Back-bay flat (4 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) |
Early season channel catfish use the shallows, holding in 3 to 12 ft. Even in summer they hold at 4 to 12 ft; winter keeps them in 4 to 12 ft. The chart's best answer is Deep basin — deep basin, 12 ft, prime for winter. Best bite is after dark and the evening.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 3 to 12 ft | dusk | Back-bay flat (4 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) |
Union Grove Lake carries 6 mapped structure features, topping out (or rather bottoming out) at Deep basin, about 12 ft down.
Access data: OpenStreetMap contributors (ODbL) — community-mapped launches. 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 Union Grove Lake specifically, so confirm the current rules before you fish.
Check the official Iowa fishing regulations →
Union Grove 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 largemouth bass, bluegill, crappie, yellow perch, channel catfish on Union Grove 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. The interactive chart above rates every spot for each species and season.
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 Union Grove 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.
Otter Creek Lake 12 mi · Green Castle Lake 16 mi · Casey Lake (aka Hickory Hills Lake) 23 mi · Lower Pine Lake 24 mi · Upper Pine Lake 24 mi · Rock Creek Lake 27 mi · Mariposa Lake 27 mi · Arbor Lake 27 mi · South Prairie Lake 28 mi · Green Belt Lake 30 mi · Iowa River 31 mi · Meyers Lake 32 mi
See how Union Grove 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.