Minnesota · St. Louis County
Boulder Lake Fishing guide
Boulder Lake is a 3,260-acre lake in St. Louis County, Minnesota, reaching 18 ft at its deepest point. Average water clarity runs about 5.5 ft. The Minnesota DNR has surveyed the lake 16 times, most recently in 2025, with walleye, northern pike, bluegill and crappie in the nets.
DNR survey data
Fish species
WalleyeExcellent numbers6.7per gill net14"Typical25"Biggest
Lengths measured · 131 fish
Recent · 2023Lengths measured · 457 fish
2025Lengths measured · 320 fish
2024Lengths measured · 307 fish
2023Lengths measured · 131 fish
2023Northern pikeJust a few2.6per gill net19"Typical23"Biggest
Lengths measured · 62 fish
Recent · 2023Lengths measured · 62 fish
2023Lengths measured · 62 fish
2018Lengths measured · 61 fish
2013Lengths measured · 61 fish
2008No recent survey rating.
CrappieJust a few0.6per trap net10"Typical13"Biggest
Lengths measured · 13 fish
Recent · 2023Lengths measured · 13 fish
2023Lengths measured · 102 fish
2018Lengths measured · 80 fish
2013Lengths measured · 51 fish
2008Yellow perchFair numbers4.3per gill net7"Typical11"Biggest
Lengths measured · 101 fish
Recent · 2023Lengths measured · 101 fish
2023Lengths measured · 125 fish
2018Lengths measured · 186 fish
2013Lengths measured · 113 fish
2008Rates 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 Boulder Lake through the year
Walleye
- Spring
- Walleye are shallow, on and just off the spawning flats and the first green weeds.
- 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. With 98% of this lake 15 ft or shallower, the weed edge is the main event.
- Fall
- Walleye are packing onto the sharpest breaks and points as the water cools, in big schools with short windows. A 18-ft bowl cools fast, so the fall window comes early here.
Northern pike
- Spring
- Pike are in the shallow bays and along new weed growth.
- Early summer
- Pike are on the outside weed edge and points.
- Summer
- Pike are on the deep weed edge and points near the coolest water they can find. With 98% of this lake 15 ft or shallower, the weed edge is the main event.
- Fall
- Pike are on the last green weeds and the breaks beside them, feeding heavily as the water drops. A 18-ft bowl cools fast, so the fall window comes early here.
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 | Northern pike | Yellow perch |
|---|---|---|---|
| 2025 | 9" | — | — |
| 2024 | 10" | — | — |
| 2023 | 25" | 23" | 11" |
| 2022 | 9" | — | — |
| 2021 | 9" | — | — |
| 2020 | 9" | — | — |
| 2018 | 27" | 25" | 11" |
| 2017 | 9" | — | — |
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 · Trolling
Planer Board Spread
4–6" crankbait or a 5–6 ft crawler harness run out to the side on an in-line planer board
Northern pike · Soft plastics
Paddletail Swimbait on Jighead
4–5" paddletail swimbait on a ball-head swimbait jighead
Northern pike · Jigs & bladed
Spinnerbait
3/8–1/2 oz safety-pin spinnerbait with tandem willow-leaf blades
Yellow perch · Soft plastics
Curly-Tail Grub on Jig
3" curly-tail grub threaded on a round jighead
Yellow perch · Soft plastics
Tungsten Jig + Micro Plastic
1–1.5" micro plastic
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
Boulder is a 3,260-acre reservoir located 12 miles north of Duluth, MN, and can be publicly accessed at the terminus of Boulder Dam Road. Maximum depth is 18 feet and lies in the Cloquet River watershed and is located just upstream of Island Lake Reservoir, near headwater reaches of the Otter River watershed. Boulder is operated as a water storage reservoir by Minnesota Power and is subject to water-level manipulation. The reservoir was constructed in 1919 and overfilled several smaller natural lakes, including Boulder, Little Boulder, and Otter lakes.
The 2024 Lake Management Plan (LMP) identifies Walleye as the primary management species. Walleye have not been stocked in Boulder since 1991 due to adequate natural reproduction. The LMP goals for Walleye are to maintain high gill net catch rates (greater than 9.5 fish per lift) with a balanced size structure, and the availability of some large Walleye exceeding 20 inches. Anglers can help achieve this goal through selective harvest and proper catch-and-release techniques.
Read the full DNR narrative
To help estimate spawning success and evaluate future year-class strength, a fall young-of-the-year (YOY) Walleye electrofishing assessment was conducted on Boulder in October 2025. This annual survey provides information on the abundance and average length of Walleye from the juvenile year classes.
A total of 445 YOY Walleye averaging 5.5 inches were captured, resulting in a historical high catch rate of 358.7 fish per hour of electrofishing. Previous YOY catch rates have ranged from 13.6 to 325.3 per hour, with a long-term average of 136.8. The abundance of YOY Walleye captured suggests that the 2025 year-class may be very strong.
A total of 12 age-1 Walleye averaging 8.7 inches were captured, yielding a catch rate of 9.7 per hour of electrofishing. Historical catch rates for age-1 Walleye have ranged from 5.2 to 72.5 per hour, with a long-term average of 23.6 per hour. The below-average catch rate of age-1 Walleye suggests the 2024 year class may be weaker than average.
With three consecutive strong years of YOY catch rates, Walleye angling on Boulder is expected to remain strong in 2026 and beyond, offering anglers opportunities to catch good numbers of quality fish.
Narrative text from the Minnesota DNR lake survey.
Recent reports
Boulder Lake fishing reports
Recent reports on Boulder 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.
Open the live map → Fished it lately? Write a report
All Boulder Lake fishing reports → · St. Louis County reports
Public water access
Getting on the water
- Boulder Lake (trailer launch)
DNR bathymetry
Boulder Lake depth map
Within 30 miles
Nearby lakes
- Island Lake Reservoir · 8,001 ac · 3 mi
- Apple Lake · 31 ac · 4.1 mi
- Jacobs Lake · 90 ac · 4.8 mi
- Schultz Lake · 210 ac · 5.2 mi
- Cooks Lake · 97 ac · 5.8 mi
- Clearwater Lake · 15 ac · 6.6 mi
- Spring Lake · 98 ac · 8.1 mi
- Eagle Lake · 114 ac · 9.1 mi
Quick answers
Frequently asked questions
How deep is Boulder Lake?
Boulder Lake reaches 18 ft at its deepest point with a mean depth of 8.1 ft; about 98% of the lake is littoral (15 ft or shallower).
How big is Boulder Lake?
Boulder Lake covers 3,260 acres with about 35.1 miles of shoreline.
How clear is the water in Boulder Lake?
DNR Secchi readings on Boulder Lake average 5.5 ft of visibility, middling clarity for a Minnesota lake.
What fish are in Boulder Lake?
Minnesota DNR surveys (most recently 2025) record walleye, northern pike, bluegill, crappie, yellow perch, rock bass.
Is Boulder Lake stocked?
No stocking is on record for Boulder Lake in the DNR's stocking database.
Does Boulder Lake have a public access?
Yes. Boulder Lake has one public access site: Boulder Lake (trailer launch).
How big do walleye get in Boulder Lake?
The biggest walleye measured in recent DNR surveys taped 25"; the size-history table on this page tracks the biggest fish in each survey back to 2017.
When was Boulder Lake last surveyed?
The Minnesota DNR last surveyed Boulder Lake in 2025, the most recent of 16 surveys on record.
Page updated .
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