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B

Lake Winnibigoshish

Cass County, MinnesotaMesotrophic

Lake Winnibigoshish carries a solid B grade — strong on most parameters, with measurements that hold up well across the summer season. The two scored sub-grades — clarity and chlorophyll-a — track close together, so neither one is dragging the average down.

The lake sits in the mesotrophic zone — the band where most well-managed Minnesota lakes fall. Lake Winnibigoshish is unusually deep for Minnesota at 70 ft, which buffers the lake against summer warming and helps the deep water stay oxygenated. Lake Winnibigoshish covers 56,471 acres alongside 69.8 miles of shoreline, large enough that conditions can vary meaningfully between bays. Within the 132 graded lakes of Cass County, Lake Winnibigoshish sits at rank 107, near the bottom of the county list.

Lake Winnibigoshish is on the Minnesota infested-waters list for zebra mussels — boaters should follow clean-drain-dry protocols when moving gear to or from the lake. Muskie are on the species list at Lake Winnibigoshish, among the lake's 20 documented fish. Public access is available — the lake is on the Minnesota PCA public-access list. The lake has a long ice-out record — 30 observations on file, with a median ice-out around Apr 27. The grade is based on limited monitoring — fewer than three independent measurement years contribute, so future updates may shift the letter.

Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-10-14. Grade methodology: LakeGrade methodology.

Reviewed by LakeQuality Editorial Team · Updated

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Swimming Safety

Good for swimming, clear water with low algae levels

Water Quality Grade: B, Good

Good clarity, visible to about 12.1 ft. Chlorophyll-a: 5.3 µg/L. Trophic State Index: 44.

MetricValueGrade
Water Clarity (Secchi Depth)12.1 ftB
PhosphorusNo data
Chlorophyll-a (Algae)5.3 µg/LB
Trophic State Index (TSI)44Mesotrophic

Moderate nutrients, good water quality

Lake Details

CharacteristicValue
Maximum Depth69.8 ft
Average Depth15.1 ft
Surface Area56.5K acres
Shoreline Length69.8 mi
Littoral Zone33%
Public AccessYes

Fish Species

black bullhead,black crappie,bluegill,bowfin (dogfish),brown bullhead,burbot,hybrid sunfish,largemouth bass,muskellunge,northern pike,pumpkinseed,rock bass,shorthead redhorse,silver redhorse,sunfish,tullibee (cisco),walleye,white sucker,yellow bullhead,yellow perch

Click a species to see all Minnesota and Wisconsin lakes where it is found.

→ Best fishing times for Lake Winnibigoshish (14-day solunar calendar)

→ Is it safe to eat fish from Lake Winnibigoshish? (mercury & PFAS guide)

Lake Winnibigoshish fishing regulations (limits, seasons, special rules)

Invasive & Introduced Species

Red chips are ecologically harmful invasive species. Gray chips are stocked or introduced fish that aren't a current ecological concern.

faucet snailstarry stonewortzebra mussel

Water Quality Trend: Declining

Based on 2 years of monitoring data (2020-2025).

MetricTrendChange/YearYears
Water Clarity Declining-1.17 m/yr2
Chlorophyll-a Stable-0.1 µg/L/yr2

Ice Season

Historical ice data from Minnesota DNR (32 observations).

Typical Ice-Out
Apr 27
EarliestLatest
Ice-Out2012-03-30 (2012)2013-05-17 (2013)
Ice-In2023-11-29 (2023)2019-12-02 (2019)

Most recent ice-out: 2025-04-29

Location

Loading map…

County Ranking

Ranked #107 of 132 lakes in Cass County

Cleaner Lakes Within 30 Miles

Lake Winnibigoshish holds Grade B. 4 nearby lakes hold higher grades.

See full comparison →

Nearby Lakes in Cass County

State Parks Near Lake Winnibigoshish

DNR Fisheries Survey Summary

38 surveys on file from MN DNR Fisheries. Most recent: 2024-05-16 (Standard Survey).

Top Species by Catch Rate

SpeciesAvg CPUEAvg Weight
Yellow Perch227.140.19 lb
Spottail Shiner109.89
MMS75.59
Bluntnose Minnow22.18
Walleye20.751.18 lb
SUN13.15

CPUE = catch per unit effort, averaged across surveys (excludes juvenile shoreline seining). Higher CPUE = more abundant in standardized sampling.

Length Distributions

Number of fish caught at each inch class in the most recent survey that recorded lengths. Red dashed line marks an approximate trophy threshold for that species.

Yellow Perch

634 fish · 212 in · 2024-05-16
184920trophy 1223456789101112

Walleye

181 fish · 324 in · 2024-05-16
30150trophy 244681012141618202224

From the 2024-05-16 survey

Lake Winnibigoshish, otherwise known as Winnie or Big Winnie, is a large reservoir located immediately north of the community of Bena, Minnesota. Winnie was a natural lake that was impounded in the 1880's with a dam controlled by the U.S. Army Corps of Engineers (USACE). Today the USACE maintains water levels within a…

Source: MN DNR LakeFinder Fisheries Lake Survey

DNR Reports & Resources

Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Lake Winnibigoshish. 4 reports on file.

Reservoir Info (USACE NID)

Lake Winnibigoshish is a man-made reservoir impounded by the Winnibigoshish Dam - Dike 1 (completed 1884), built primarily for water supply on the MISSISSIPPI RIVER; earth-type dam, 5 ft tall and 50 ft long.

Surface area
68,000 ac
Normal storage
220,000 ac-ft
Max storage
550,000 ac-ft
Drainage area
1,442 sq mi
Hazard class
Significant
Owner
USACE - St. Paul District

All listed purposes: Water Supply;Navigation;Fish and Wildlife Pond;Recreation;Flood Risk Reduction.

Source: USACE National Inventory of Dams, NID ID MN00586 · Operator website

Data Sources

Water quality data from the EPA Water Quality Portal

Grading methodology based on Metropolitan Council standards

Lake details from Minnesota DNR LakeFinder

Ice data from Minnesota DNR Climate

Most recent sample: 2025-10-14

Monitoring stations: 1