Minnesota · Cook County
Alton Lake Fishing guide
Alton Lake covers 969 acres in Cook County, Minnesota, reaching 72 ft at its deepest point. Secchi readings average around 14.2 ft of visibility. The Minnesota DNR has surveyed the lake 12 times, most recently in 2025, with walleye, smallmouth bass, northern pike and yellow perch in the nets.
DNR survey data
Fish species
WalleyeFair numbers3.6per gill net15"Typical24"Biggest
Lengths measured · 42 fish
Recent · 2018Lengths measured · 42 fish
2018Lengths measured · 54 fish
2008Lengths measured · 72 fish
2003Lengths measured · 25 fish
1996Smallmouth bassPresent (last recorded 2018)3.8per gill net11"Typical18"Biggest
Lengths measured · 70 fish
Recent · 2018Lengths measured · 70 fish
2018Lengths measured · 7 fish
2008Only 7 fish measured that year — too few to read as a shape.
Lengths measured · 7 fish
2003Only 7 fish measured that year — too few to read as a shape.
Lengths measured · 9 fish
1996Only 9 fish measured that year — too few to read as a shape.
Last recorded in the 2008 survey and not seen since.
Last recorded in the 1990 survey and not seen since.
Rock bassGood numbers2per gill net7"Typical8"Biggest
Lengths measured · 26 fish
Recent · 2018Lengths measured · 26 fish
2018Lengths measured · 53 fish
2008Lengths measured · 21 fish
2003Lengths measured · 4 fish
1996Only 4 fish measured that year — too few to read as a shape.
Rates come from standard DNR survey gear (gill nets, trap nets, electrofishing), judged against statewide benchmarks for the same gear, so the same number of fish per net can read differently for two species. Where the standard gear can't count a species reliably, only presence and size are listed. Typical is the middle fish of those measured. Open a row for the full length spread, survey by survey.
How to fish Alton Lake through the year
Walleye
- Spring
- Walleye are shallow, on and just off the spawning flats and the first green weeds. At 14.2 ft of clarity, fish them deeper and lighter than usual.
- Early summer
- Walleye are setting up on the outside weed edge, points and shallow structure.
- Summer
- Walleye are working the weed edge, points and any wind-blown structure. On a lake that drops to 72 ft, check the deep edge of that structure too.
- Fall
- Walleye are packing onto the sharpest breaks and points as the water cools, in big schools with short windows.
Smallmouth bass
- Spring
- Smallmouth are on shallow rock, gravel and sand where they spawn. At 14.2 ft of clarity, fish them deeper and lighter than usual.
- Early summer
- Smallmouth are post-spawn on rock points, gravel bars and the adjacent breaks.
- Summer
- Smallmouth are on rock humps, points and hard-bottom breaks. On a lake that drops to 72 ft, check the deep edge of that structure too.
- Fall
- Smallmouth are bunched tight on deep rock, so find one and you have found the school.
Season patterns for each species. Open the live map for today's wind, light and water temp.
Size history
Biggest fish by survey year
| Survey year | Walleye | Smallmouth bass | Northern pike |
|---|---|---|---|
| 2018 | 24" | 18" | 23" |
| 2008 | 30" | 15" | 15" |
| 2003 | 27" | 16" | 25" |
| 1996 | 28" | 14" | 31" |
Longest fish measured by DNR survey crews in each year's nets. Survey gear samples the population, so the lake usually holds larger fish than any survey measured.
Suggested tackle
What to bring
Top presentations for this lake's structure and clarity:
Walleye · Live bait
Live-Bait (Lindy) Rig + Leech/Crawler
jumbo leech or half a nightcrawler
Walleye · Trolling
Leadcore Line + Crankbaits
4–5" mid-diving crankbait behind a long leadcore run
Smallmouth bass · Soft plastics
Drop Shot (Finesse Plastic)
4" finesse worm or 3" minnow-profile plastic
Smallmouth bass · Jigs & bladed
Tail Spinner
Compact lead body with a free-spinning blade on the tail
Northern pike · Soft plastics
Paddletail Swimbait on Jighead
4–5" paddletail swimbait on a ball-head swimbait jighead
Northern pike · Muskie & pike
Soft Rubber (Bull Dawg / Medusa)
10" soft rubber body bait
Full setups, including hooks, weights and line, are on the live map. As an Amazon Associate I earn from qualifying purchases.
MN DNR · in their words
From the 2025 survey
Temperature and dissolved oxygen (DO) measurements were collected from the deepest basin in Alton Lake on August 4th, 2025, to evaluate the quantity and quality of cold, oxygenated water (i.e., oxythermal habitat) available to Cisco, also known as Tullibee, the most sensitive coldwater species present in this lake. During the summer, Cisco require a layer of oxythermal habitat that contains water temperatures below 21.2 degrees C (70.2 degrees F) and dissolved oxygen concentrations above 3.0 mg/L. Based on the profile from the deepest basin (maximum sampled depth 55.8 feet), the water temperature decreased below 21.2 degrees C (70.2 degrees F) at 23.0 feet and the dissolved oxygen concentration decreased to 3.0 mg/L at 39.8 feet at the time of sampling. The thickness of this layer of water in the water column was 16.9 feet, indicating that oxythermal habitat was present for Cisco.
Further, the temperature at which dissolved oxygen decreased to 3.0 mg/L (i.e., TDO3, a single variable to characterize oxythermal habitat) was 9.7 degrees C (49.5 degrees F). TDO3 values cooler than 21.2 degrees C (70.2 degrees F) indicate that oxythermal conditions were suitable for Cisco at the time of the survey.
Read the full DNR narrative
Data collected by the Minnesota Department of Natural Resources during the late summer period of maximum oxythermal stress (July 26th to Aug 24th) in 2008, 2023, and 2024 also indicate suitable oxythermal habitat in all years surveyed. When inadequate oxythermal habitat is available, Cisco are squeezed into unfavorable, warmer water conditions and experience higher levels of stress.
Narrative text from the Minnesota DNR lake survey.
Recent reports
Alton Lake fishing reports
Recent reports on Alton Lake from guides, tournaments and regular anglers. Anything posted in the last two weeks also bumps the matching spots on the live map, so you'll see a "matches a recent report" tag on them.
Public water access
Getting on the water
- US Forest Service access (permit required): A 30 rod portage from Sawbill Lake. This is the main access route and is used as an entry point to other lakes in the BWCA.
- US Forest Service access (permit required): The Kelso Lake portage is approximately 10 rods; found on the north end of Alton Lake.
- US Forest Service access (permit required): The Beth Lake portage is approximately 120 rods; on the southwest end of Alton Lake.
- US Forest Service access (permit required): Portage trail to Wonder Lake on the southeast shore of the southern most bay. The portage trail is approximately 220 rods and leads to the northeast corner of Wonder Lake.
DNR bathymetry
Alton Lake depth map
Within 30 miles
Nearby lakes
- Beth Lake · 170 ac · 1.9 mi
- Wonder Lake · 80 ac · 2.1 mi
- Sawbill Lake · 834 ac · 2.5 mi
- Kelso Lake · 133 ac · 2.6 mi
- Grace Lake · 433 ac · 2.7 mi
- Phoebe Lake · 610 ac · 4.6 mi
- Vyre Lake · 22 ac · 4.8 mi
- Wine Lake · 268 ac · 5.6 mi
Quick answers
Frequently asked questions
How deep is Alton Lake?
Alton Lake reaches 72 ft at its deepest point; about 33% of the lake is littoral (15 ft or shallower).
How big is Alton Lake?
Alton Lake covers 969 acres with about 15.4 miles of shoreline.
How clear is the water in Alton Lake?
DNR Secchi readings on Alton Lake average 14.2 ft of visibility, clear water for a Minnesota lake.
What fish are in Alton Lake?
Minnesota DNR surveys (most recently 2025) record walleye, smallmouth bass, northern pike, yellow perch, brook trout, lake trout, rock bass.
Is Alton Lake stocked?
No stocking is on record for Alton Lake in the DNR's stocking database.
Does Alton Lake have a public access?
Yes. Alton Lake has 4 public access sites, including a US Forest Service access (A 30 rod portage from Sawbill Lake. This is the main access route and is used as an entry point to other lakes in the BWCA.).
How big do walleye get in Alton Lake?
The biggest walleye measured in recent DNR surveys taped 24"; the size-history table on this page tracks the biggest fish in each survey back to 1996.
When was Alton Lake last surveyed?
The Minnesota DNR last surveyed Alton Lake in 2025, the most recent of 12 surveys on record.
Page updated .
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