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149-acre lake near Crow Wing County. The lake tops out around 350 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. Species by species, here's what the data says the year looks like.
On the chart, Portsmouth Mine draws 149 acres inside 3.1 miles of shoreline. The shoreline is moderately structured (index 1.8) — enough points and pockets to pattern. Littoral water — the productive band under ~15 ft — makes up 3% of this chart. Call it 1 mi long by 0.4 mi wide at the broadest reach. The water lies in Crow Wing County. The nearest mapped water is Pennington Mine, 1 mi to the southwest.
Spring puts rainbow trout in skinny water — 5 to 20 ft is the zone. Warm water sends them out to 8 to 30 ft; cold water stacks them in 8 to 40 ft. Secondary point is the standout, a point at roughly 18 ft, rated prime for spring rainbow trout. Plan around early morning and the evening in the warm months. A dodger + spoon (deep troll) or a flutter spoon covers the summer program.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 5 to 20 ft | dawn & dusk | Secondary point (18 ft) | Inline spinner (silver), Small spoon |
| Summer | 8 to 30 ft | dawn & dusk | Secondary point (18 ft) | Dodger + spoon (deep troll), Flutter spoon |
| Fall | 10 to 35 ft | dawn & dusk | Secondary point (18 ft) | Casting spoon, Jerkbait over shoals |
| Winter | 8 to 40 ft | dawn | Break off the point (139 ft) | Jigging spoon, Tube jig (white) |
Come spring, look for yellow perch tight to the bank in 3 to 12 ft. Expect a summer slide to 10 to 30 ft, then a winter hold in 15 to 35 ft. Start at Back-bay flat. It's a feeding flat holding about 5 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 12 ft | midday & dawn | Back-bay flat (5 ft) | Small jig + curly tail, Perch-pattern micro crank |
| Summer | 10 to 30 ft | dawn | Shallow bay flat (21 ft) | Drop-shot micro plastics, Small spoon tipped with worm |
| Fall | 12 to 35 ft | midday | Deep basin (350 ft) | Jigging spoon (small), Perch rig / spreader |
| Winter | 15 to 35 ft | midday & dawn | Shallow bay flat (21 ft) | Tungsten jig + spikes, Rattle spoon (small) |
Start shallow in spring: northern pike sit in 2 to 8 ft that time of year. Summer pushes them deeper, 8 to 20 ft, and winter fish settle into 5 to 15 ft. The spot to know is Back-bay flat, a feeding flat in about 5 ft of water that rates prime for northern pike in spring. Warm-month bites cluster around early morning and the evening. Throw a bucktail or a weedless spoon over cabbage until the fish tell you otherwise.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 2 to 8 ft | midday & dawn | Back-bay flat (5 ft) | #5 inline spinner, Spoon (red/white) |
| Summer | 8 to 20 ft | dawn & dusk | Secondary point (18 ft) | Bucktail, Weedless spoon over cabbage |
| Fall | 6 to 18 ft | midday & dawn | Secondary point (18 ft) | Big rubber (Bull Dawg style), Husky-style jerkbait |
| Winter | 5 to 15 ft | midday | Back-bay flat (5 ft) | Tip-ups, Large jigging spoon |
The spring pattern is a shallow one: largemouth bass in 2 to 10 ft. As the season builds they drop to 8 to 20 ft, wintering in 15 to 35 ft. Top water on the chart: Back-bay flat, a feeding flat in the 5 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 | Back-bay flat (5 ft) | Spinnerbait, Chatterbait |
| Summer | 8 to 20 ft | dawn & dusk | Secondary point (18 ft) | Texas-rigged 10" worm, Deep-diving crankbait |
| Fall | 4 to 15 ft | midday & dawn | Secondary point (18 ft) | Squarebill crankbait (shad), Spinnerbait |
| Winter | 15 to 35 ft | midday | Break off the point (139 ft) | Blade bait, Jigging spoon |
Early season rock bass use the shallows, holding in 2 to 10 ft. Expect a summer slide to 5 to 20 ft, then a winter hold in 12 to 30 ft. Put Secondary point first on the milk run — a point near 18 ft that grades prime for summer. In summer the feeding windows fall in the evening. Tie on a ned rig (small) or a marabou jig and you're in the game.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 2 to 10 ft | midday & dawn | open water | 1/16 oz jig + grub, Small inline spinner |
| Summer | 5 to 20 ft | dusk | Secondary point (18 ft) | Ned rig (small), Marabou jig |
| Fall | 8 to 22 ft | midday | Secondary point (18 ft) | Small tube jig, Inline spinner |
| Winter | 12 to 30 ft | midday | Deep basin (350 ft) | Tungsten jig + plastic, Small spoon + spike |
Start shallow in spring: crappie sit in 2 to 8 ft that time of year. Summer pushes them deeper, 10 to 25 ft, and winter fish settle into 15 to 35 ft. The spot to know is Back-bay flat, a feeding flat in about 5 ft of water that rates prime for crappie in spring. 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 | Back-bay flat (5 ft) | 1/16 oz jig + tube, Curly-tail grub |
| Summer | 10 to 25 ft | dawn & dusk | Shallow bay flat (21 ft) | Jig trolled/spider-rigged, Small crankbait (trolled) |
| Fall | 8 to 20 ft | dawn | Shallow bay flat (21 ft) | Jig + minnow combo, Small swimbait (1.5-2") |
| Winter | 15 to 35 ft | midday | Deep basin (350 ft) | Tungsten jig + soft plastic, Tiny jigging spoon |
Portsmouth Mine also holds bluegill (4 to 15 ft in summer), pumpkinseed (2 to 10 ft in summer). Pick any of them on the map above for rated spots and bait picks.
Count 6 structure marks on this chart. The deepest, Deep basin, sits near 350 ft.
Access data: OpenStreetMap contributors (ODbL) — community-mapped launches. Confirm conditions and fees locally before you launch.
| Date | Species | Count | Size |
|---|---|---|---|
| 2025* | Rainbow Trout (yearlings) | 7,500 | — |
| 2025* | Rainbow Trout (adults) | 66 | — |
| 2024* | Rainbow Trout (yearlings) | 7,000 | — |
* Approximate date (agency reports month or season only). Source: Minnesota DNR LakeFinder stocking reports, retrieved 2026-08-18.
Season dates, license requirements, and size and bag limits for Minnesota waters are set by the Minnesota DNR — and special regulations can apply to Portsmouth Mine specifically, so confirm the current rules before you fish.
Check the official Minnesota fishing regulations →
Portsmouth Mine is about 350 ft (107 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 rainbow trout, yellow perch, northern pike, largemouth bass, rock bass, crappie, bluegill, pumpkinseed on Portsmouth Mine.
Secondary point is the top-rated area: a point in about 18 ft of water that rates prime for rock bass in summer. The map above holds the full rated-spot list for every species and season.
For rainbow trout, 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.
Yes — per Minnesota DNR LakeFinder stocking reports records, Portsmouth Mine was most recently stocked 2025 with 7,500 rainbow trout (yearlings). The full stocking history is listed above.
Fishing on Portsmouth Mine is regulated by the Minnesota DNR. Check the official Minnesota regulations for current license requirements, season dates, and size and bag limits — special regulations can apply to this specific water.
Pennington Mine 1 mi · Manuel Mine 1 mi · Turner 1 mi · Mahnomen, Alstead & Arco 1 mi · Mahnomen 2 mi · Serpent 2 mi · Huntington Mine 2 mi · Clinker 2 mi · Morroco Mine 2 mi · June 2 mi · Black Hoof 3 mi · Agate 3 mi
See how Portsmouth Mine stacks up: best largemouth bass lakes in Minnesota · best northern pike lakes in Minnesota · best crappie lakes in Minnesota · best bluegill lakes in Minnesota
More water nearby: Crow Wing County fishing maps (202 charts). Browse all Minnesota 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.