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880-acre lake near Afton. The lake tops out around 48 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 follows comes from the same scoring engine that paints the spots above.
Traced from the shoreline, Three Mile Lake runs 799 acres with 17.6 miles of edge. The 4.4 development index tells the story — a convoluted bank whose fishable edge far outruns the acreage. 52% of the surface is littoral (under ~15 ft) — cover, weeds and forage water. Figure 3.8 mi of water from one end to the other, 1.3 mi at the beam. You'll find it in Union County. Closest neighbour on DepthScout: Twelve Mile Creek Lake, 2 mi southwest of here.
Spring walleye on Three Mile Lake hold shallow, usually 4 to 15 ft. By summer they slide out to 15 to 35 ft, and by winter most fish are in 20 to 40 ft. The chart's best answer is Break off the point — drop-off, 25 ft, prime for fall. Prime time lands in the evening and early morning. The summer box starts with a crawler harness on bottom bouncer or a deep crankbait (trolled).
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 4 to 15 ft | dusk & dawn | Main-lake point (6 ft) | 1/8 oz jig + minnow, Hair jig |
| Summer | 15 to 35 ft | dusk & dawn | Break off the point (25 ft) | Crawler harness on bottom bouncer, Deep crankbait (trolled) |
| Fall | 12 to 40 ft | dusk & night | Break off the point (25 ft) | Jigging rap, Jig + big minnow |
| Winter | 20 to 40 ft | dusk & dawn | Break off the point (25 ft) | Jigging spoon + minnow head, Rattle bait |
Spring puts largemouth bass in skinny water — 2 to 10 ft is the zone. Warm water sends them out to 8 to 20 ft; cold water stacks them in 15 to 35 ft. Shallow bay flat is the standout, a weed flat at roughly 2 ft, rated prime for spring largemouth bass. Plan around early morning and the evening in the warm months. A texas-rigged 10" worm or a deep-diving crankbait covers the summer program.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 2 to 10 ft | dawn & dusk | Shallow bay flat (2 ft) | Spinnerbait, Chatterbait |
| Summer | 8 to 20 ft | dawn & dusk | Secondary point (8 ft) | Texas-rigged 10" worm, Deep-diving crankbait |
| Fall | 4 to 15 ft | midday & dawn | Main-lake point (6 ft) | Squarebill crankbait (shad), Spinnerbait |
| Winter | 15 to 35 ft | midday | Break off the point (25 ft) | Blade bait, Jigging spoon |
Start shallow in spring: muskellunge sit in 3 to 12 ft that time of year. Warm water sends them out to 8 to 25 ft; cold water stacks them in 15 to 35 ft. Top water on the chart: Break off the point, a drop-off in the 25 ft range, prime in fall. Fish it in the evening and early morning and you'll meet the bite. Throw a double-10 bucktail or a topwater (walk-the-dog / creeper) until the fish tell you otherwise.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 3 to 12 ft | dusk | Back-bay flat (3 ft) | Smaller bucktail (#8 blades), 6" glide bait |
| Summer | 8 to 25 ft | dusk & dawn | Secondary point (8 ft) | Double-10 bucktail, Topwater (walk-the-dog / creeper) |
| Fall | 8 to 30 ft | midday & dusk | Break off the point (25 ft) | Big rubber (Bull Dawg style), 10"+ glide bait |
| Winter | 15 to 35 ft | midday | Break off the point (25 ft) | Large rubber, crawled slow |
In spring, crappie run shallow here, mostly 2 to 8 ft. Midsummer fish sit out in 10 to 25 ft before dropping to 15 to 35 ft for winter. Spring crappie 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 jig trolled/spider-rigged or a small crankbait (trolled) most summer days.
| 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 | 10 to 25 ft | dawn & dusk | Break off the point (25 ft) | Jig trolled/spider-rigged, Small crankbait (trolled) |
| Fall | 8 to 20 ft | dawn | Dock / pier line (11 ft) | Jig + minnow combo, Small swimbait (1.5-2") |
| Winter | 15 to 35 ft | midday | Break off the point (25 ft) | Tungsten jig + soft plastic, Tiny jigging spoon |
Start shallow in spring: bluegill sit in 1 to 6 ft that time of year. Warm water sends them out to 4 to 15 ft; cold water stacks them in 10 to 25 ft. Top water on the chart: Shallow bay flat, a weed flat in the 2 ft range, prime in spring. Fish it in early morning and the evening and you'll meet the bite. Throw a small sponge spider (fly) or a micro tube jig until the fish tell you otherwise.
| 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 | 4 to 15 ft | dawn & dusk | Back-bay flat (3 ft) | Small sponge spider (fly), Micro tube jig |
| Fall | 6 to 18 ft | midday | Dock / pier line (11 ft) | Micro jig + waxworm, Small spoon tipped |
| Winter | 10 to 25 ft | midday | Break off the point (25 ft) | Tungsten ice jig + plastic, Tiny spoon |
Spring puts channel catfish in skinny water — 3 to 12 ft is the zone. Warm water sends them out to 8 to 25 ft; cold water stacks them in 20 to 40 ft. Deep basin is the standout, a deep basin at roughly 44 ft, rated prime for winter channel catfish. Plan around after dark and the evening in the warm months.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 3 to 12 ft | dusk | Back-bay flat (3 ft) | |
| Summer | 8 to 25 ft | night & dusk | Shallow feeding flat (20 ft) | |
| Fall | 10 to 30 ft | dusk | Shallow feeding flat (20 ft) | |
| Winter | 20 to 40 ft | midday | Deep basin (44 ft) |
8 pieces of structure are mapped here — Deep basin, around 44 ft, is the deepest of them.
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 Three Mile Lake specifically, so confirm the current rules before you fish.
Check the official Iowa fishing regulations →
Three Mile Lake is about 48 ft (15 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 walleye, largemouth bass, muskellunge, crappie, bluegill, channel catfish on Three Mile Lake.
Break off the point is the top-rated area: a drop-off in about 25 ft of water that rates prime for walleye in fall. The interactive chart above rates every spot for each 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 Three Mile 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.
Twelve Mile Creek Lake 2 mi · Hurley Creek Pond 7 mi · Green Valley Lake 8 mi · McKinley Lake 8 mi · Summit Lake 8 mi · Thayer Lake 10 mi · Orient Lake 13 mi · Greenfield Lake 19 mi · Nodaway Lake 19 mi · Fogle Lake S.W.A. 20 mi · West Lake (Osceola) 22 mi · Meadow Lake 23 mi
See how Three Mile 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.