Minnesota · Scott County
McMahon Lake Fishing guide
McMahon Lake covers 187 acres in Scott County, Minnesota, reaching 14 ft at its deepest point. Average water clarity runs about 5.3 ft. The Minnesota DNR has surveyed the lake 9 times, most recently in 2025, with walleye, largemouth bass, northern pike and bluegill in the nets.
DNR survey data
Fish species
WalleyeLast stocked 2025Good numbers5.4per gill net21"Typical26"Biggest
Lengths measured · 28 fish
Recent · 2025Lengths measured · 28 fish
2025Lengths measured · 27 fish
2015Lengths measured · 47 fish
2010Lengths measured · 46 fish
2004Largemouth bassPresent2.2per gill net14"Typical17"Biggest
Lengths measured · 20 fish
Recent · 2025Lengths measured · 20 fish
2025Lengths measured · 9 fish
2015Only 9 fish measured that year — too few to read as a shape.
Lengths measured · 16 fish
2010Lengths measured · 7 fish
2004Only 7 fish measured that year — too few to read as a shape.
Northern pikeOne of the best around28.8per gill net20"Typical35"Biggest
Lengths measured · 147 fish
Recent · 2025Lengths measured · 147 fish
2025Lengths measured · 76 fish
2015Lengths measured · 100 fish
2010Lengths measured · 44 fish
2004BluegillFair numbers42per trap net5"Typical9"Biggest
Lengths measured · 525 fish
Recent · 2025Lengths measured · 525 fish
2025Lengths measured · 364 fish
2015Lengths measured · 755 fish
2010Lengths measured · 445 fish
2004CrappieFair numbers14.7per trap net5"Typical10"Biggest
Lengths measured · 394 fish
Recent · 2025Lengths measured · 394 fish
2025Lengths measured · 152 fish
2015Lengths measured · 300 fish
2010Lengths measured · 399 fish
2004Yellow perchExcellent numbers21.8per gill net5"Typical9"Biggest
Lengths measured · 121 fish
Recent · 2025Lengths measured · 121 fish
2025Lengths measured · 123 fish
2015Lengths measured · 42 fish
2010Lengths measured · 51 fish
2004Rates 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 McMahon Lake through the year
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 85% 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 14-ft bowl cools fast, so the fall window comes early here.
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 85% 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 14-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 | Northern pike | Walleye | Largemouth bass |
|---|---|---|---|
| 2025 | 35" | 26" | 17" |
| 2015 | 33" | 25" | 19" |
| 2010 | 32" | 26" | 20" |
| 2004 | 34" | 27" | 20" |
| 1998 | 31" | 23" | 17" |
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:
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
Walleye · Soft plastics
Curly-Tail Grub on Jig
3" curly-tail grub threaded on a round jighead
Largemouth bass · Hardbaits
Topwater Popper
2.5–3" concave-face popper
Largemouth bass · Hardbaits
Hollow-Body Frog
3–3.5" hollow-body frog
Full setups, including hooks, weights and line, are on the live map. As an Amazon Associate I earn from qualifying purchases.
DNR stocking records
Stocking history
| Year | Species | Stocked |
|---|---|---|
| 2025 | Walleye | 1,156 fingerlings |
| 2022 | Walleye | 1,875 fingerlings |
| 2018 | Walleye | 1,000 fingerlings |
| 2017 | Walleye | 3,000 fingerlings |
| 2016 | Walleye | 2,000 fingerlings |
MN DNR · in their words
From the 2025 survey
McMahon is a 187-acre (158 littoral acres) lake with a maximum depth of 14 feet. McMahon is located south of the City of Prior Lake in southeast Scott County. McMahon is primarily managed for Bluegill and Largemouth but includes catchable populations of Black Crappie, Northern Pike, and Walleye. Public water access (concreate ramp; up to 9 vehicle/trailer parking spaces) is located on the northwest side of the lake off of county road 87 and is maintained by DNR Parks and Trails.
A Standard Survey (9 trap nets/5 gill nets) was conducted on McMahon Lake during the week of 6/23/2025 to monitor water characteristics and fish populations. Water color was brown/green, with moderate water clarity, measured at 7 feet during the time of this survey. Dissolved oxygen fell to two parts per million at 14 feet. Eurasian Watermilfoil has been identified in McMahon Lake and remains present, providing a good reminder of the clean, drain, dispose law which helps to prevent the spread of aquatic invasive species:
Read the full DNR narrative
Clean all aquatic plants, zebra mussels, and other invasive species from boats, trailers, and water-related equipment.
Drain water from your boat, ballast tanks, motor, live well and bait container. Remove drain plugs and keep drain plugs out while transporting equipment.
Dispose of unwanted bait in the trash. To keep live bait, drain the water and refill the bait container with bottled or tap water.
High numbers of Bluegill were sampled with trap nets (42.0/net), well above the expected catch rate of similar lakes. There were 378 Bluegill sampled in trap nets during the 2025 survey, with an average length of 5.3 inches and the largest measured at 9.4 inches. Despite high catch rates, Bluegill growth in McMahon was fast compared to similar lakes, indicated by an average length of 5.9 inches by age 3 and 7.8 inches by age 5. Multiple nine-inch Bluegill were sampled during the 2025 survey, demonstrating the potential for a tremendous fishery.
Largemouth Bass are present in McMahon Lake, although targeted boat-electrofishing did not occur during the 2025 survey. Incidental capture with trap and gill nets caught 20 Largemouth Bass, with an average length of 12.9 inches and the largest measured at 17.7 inches. Future surveys will include a targeted spring boat-electrofishing component.
High numbers of Black Crappie were sampled with gill nets (52.6/net) and trap nets (14.7/net) above the expected catch rates for both gears. There were 302 Black Crappie sampled during the 2025 survey, with an average length of 6.3 inches and the largest measured at 10.9 inches. Over 90% of Black Crappie measured less than 9 inches, likely providing little interest to anglers at their current sizes.
Very high numbers of Northern Pike were sampled with gill nets (28.8/net), well above the expected catch rate of similar lakes. The 2025 netting represents the highest catch rate of Northern Pike in McMahon Lake in the previous 30 years. There were 143 Northern Pike sampled in gill nets, with an average size of 21.1 inches and the largest measured at 35.0 inches. Nearly 90% of Northern Pike measured less than 24 inches. The current regulation (minimum size 24"; limit 2) does not currently leave much opportunity for harvest.
Moderate numbers of Walleye were sampled with gill nets (5.4/net), near the expected catch rate of similar lakes. There were 27 Walleye sampled in gill nets, with an average length of 21.0 inches and the largest measured at 26.0 inches. Only one Walleye measured less than 17". Stocked Walleye fingerlings may have trouble surviving until the extremely high number of Northern Pike declines. Walleye growth in McMahon was fast early on, indicated by an average length of 11.1 inches by age 2 and 20.5 inches by age 4, and slowed at older ages with an average length of 21.7 by age 7 and 20.8 inches by age 8. Despite inconstant growth, mortality of older sizes is low with Walleye aged to 13, 16, and 19 years old.
Other fish species sampled during the survey include Black Bullhead, Golden Shiner, Green Sunfish, and Yellow Perch.
Narrative text from the Minnesota DNR lake survey.
Recent reports
McMahon Lake fishing reports
Recent reports on McMahon 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
- McMahon Lake (trailer launch)
DNR bathymetry
McMahon Lake depth map
Within 30 miles
Nearby lakes
- Fish Lake · 176 ac · 2.7 mi
- Cynthia Lake · 196 ac · 3.1 mi
- Sweetbrier Lake · 20 ac · 3.5 mi
- Cleary Lake · 145 ac · 4.1 mi
- Crystal Lake · 31 ac · 4.7 mi
- Spring Lake · 592 ac · 5.3 mi
- Upper Prior Lake · 386 ac · 5.6 mi
- Cedar Lake · 793 ac · 6.2 mi
Quick answers
Frequently asked questions
How deep is McMahon Lake?
McMahon Lake reaches 14 ft at its deepest point; about 85% of the lake is littoral (15 ft or shallower).
How big is McMahon Lake?
McMahon Lake covers 187 acres with about 4.3 miles of shoreline.
How clear is the water in McMahon Lake?
DNR Secchi readings on McMahon Lake average 5.3 ft of visibility, middling clarity for a Minnesota lake.
What fish are in McMahon Lake?
Minnesota DNR surveys (most recently 2025) record walleye, largemouth bass, northern pike, bluegill, crappie, yellow perch.
Is McMahon Lake stocked?
Yes. The DNR stocked walleye in 2025; the stocking table on this page lists every year back to 2016.
Does McMahon Lake have a public access?
Yes. McMahon Lake has one public access site: McMahon Lake (trailer launch).
How big do northern pike get in McMahon Lake?
The biggest northern pike measured in recent DNR surveys taped 35"; the size-history table on this page tracks the biggest fish in each survey back to 1998.
When was McMahon Lake last surveyed?
The Minnesota DNR last surveyed McMahon Lake in 2025, the most recent of 9 surveys on record.
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