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642-acre lake near Monona County. Iowa DNR survey water. The lake tops out around 10 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.
Traced from the shoreline, Blue Lake runs 642 acres with 4.4 miles of edge. 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 1.8 mi, about 0.8 mi across. The water lies in Monona County. Closest neighbour on DepthScout: Loess Hills State Forest - Jones Creek, 17 mi southeast of here.
The spring pattern is a shallow one: largemouth bass in 2 to 10 ft. The depth story barely changes: 3 to 10 ft through summer, 3 to 10 ft in winter. Top water on the chart: Shallow bay flat, a weed flat in the 4 ft range, prime in spring. Time it for early morning and the evening. Summer baits: a texas-rigged 10" worm or a deep-diving crankbait gets it done.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 2 to 10 ft | dawn & dusk | Shallow bay flat (4 ft) | Spinnerbait, Chatterbait |
| Summer | 3 to 10 ft | dawn & dusk | Shallow bay flat (4 ft) | Texas-rigged 10" worm, Deep-diving crankbait |
| Fall | 3 to 10 ft | midday & dawn | Main-lake point (2 ft) | Squarebill crankbait (shad), Spinnerbait |
| Winter | 3 to 10 ft | midday | Break off the point (2 ft) | Blade bait, Jigging spoon |
In spring, bluegill run shallow here, mostly 1 to 6 ft. Summer pushes them deeper, 3 to 10 ft, and winter fish settle into 3 to 10 ft. Shallow bay flat is the standout, a weed flat at roughly 4 ft, rated prime for spring bluegill. Time it for early morning and the evening. You won't need more than a small sponge spider (fly) or a micro tube jig most summer days.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 1 to 6 ft | midday & dusk | Shallow bay flat (4 ft) | 1/32 oz jig + micro plastic, Tiny popper (evenings) |
| Summer | 3 to 10 ft | dawn & dusk | Shallow bay flat (4 ft) | Small sponge spider (fly), Micro tube jig |
| Fall | 3 to 10 ft | midday | Shallow bay flat (4 ft) | Micro jig + waxworm, Small spoon tipped |
| Winter | 3 to 10 ft | midday | Deep basin (10 ft) | Tungsten ice jig + plastic, Tiny spoon |
Start shallow in spring: crappie sit in 2 to 8 ft that time of year. Summer pushes them deeper, 3 to 10 ft, and winter fish settle into 3 to 10 ft. The spot to know is Deep basin, a deep basin in about 10 ft of water that rates prime for crappie in winter. Warm-month bites cluster around early morning and the evening. Throw a jig trolled/spider-rigged or a small crankbait (trolled) until the fish tell you otherwise.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 2 to 8 ft | midday & dawn | Shallow bay flat (4 ft) | 1/16 oz jig + tube, Curly-tail grub |
| Summer | 3 to 10 ft | dawn & dusk | Shallow bay flat (4 ft) | Jig trolled/spider-rigged, Small crankbait (trolled) |
| Fall | 3 to 10 ft | dawn | Shallow bay flat (4 ft) | Jig + minnow combo, Small swimbait (1.5-2") |
| Winter | 3 to 10 ft | midday | Deep basin (10 ft) | Tungsten jig + soft plastic, Tiny jigging spoon |
Come spring, look for yellow perch tight to the bank in 3 to 10 ft. Through summer count on 3 to 10 ft; the winter hold is 3 to 10 ft. Start at Shallow bay flat. It's a weed flat holding about 4 ft of water and rates prime come spring. Prime time lands in early morning. A drop-shot micro plastics or a small spoon tipped with worm is the honest summer answer here.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 3 to 10 ft | midday & dawn | Shallow bay flat (4 ft) | Small jig + curly tail, Perch-pattern micro crank |
| Summer | 3 to 10 ft | dawn | Deep basin (10 ft) | Drop-shot micro plastics, Small spoon tipped with worm |
| Fall | 3 to 10 ft | midday | Deep basin (10 ft) | Jigging spoon (small), Perch rig / spreader |
| Winter | 3 to 10 ft | midday & dawn | Deep basin (10 ft) | Tungsten jig + spikes, Rattle spoon (small) |
The spring pattern is a shallow one: channel catfish in 3 to 10 ft. The depth story barely changes: 3 to 10 ft through summer, 3 to 10 ft in winter. Top water on the chart: Deep basin, a deep basin in the 10 ft range, prime in winter. Time it for after dark and the evening.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 3 to 10 ft | dusk | Shallow bay flat (4 ft) | |
| Summer | 3 to 10 ft | night & dusk | Deep basin (10 ft) | |
| Fall | 3 to 10 ft | dusk | Deep basin (10 ft) | |
| Winter | 3 to 10 ft | midday | Deep basin (10 ft) |
Structure-wise the chart holds 7 features, led in depth by Deep basin at roughly 10 ft.
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 Blue Lake specifically, so confirm the current rules before you fish.
Check the official Iowa fishing regulations →
Blue Lake is about 10 ft (3 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 Blue 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 4 ft of water that rates prime for largemouth bass in spring. The map above holds the full rated-spot list for every 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 Blue 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.
Loess Hills State Forest - Jones Creek 17 mi · Snyder Bend Lake 18 mi · Oldham Lake 19 mi · Summit Lake 20 mi, NE · Browns Lake 21 mi · Willow Lake 27 mi · Nelson Park Lake 30 mi · Kramper Lake (Pigeon Jones) 31 mi, NE · Crawford Creek Impoundment 33 mi · Little Sioux Park Lake 34 mi · DeSoto Bend at DeSoto National Wildlife Refuge 37 mi, IA/NE · Desoto Bend 37 mi, NE/IA
See how Blue 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.