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.
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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.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 12.1 ft | B |
| Phosphorus | No data | |
| Chlorophyll-a (Algae) | 5.3 µg/L | B |
| Trophic State Index (TSI) | 44 | Mesotrophic |
Moderate nutrients, good water quality
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 69.8 ft |
| Average Depth | 15.1 ft |
| Surface Area | 56.5K acres |
| Shoreline Length | 69.8 mi |
| Littoral Zone | 33% |
| Public Access | Yes |
Fish Species
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.
Water Quality Trend: ↓ Declining
Based on 2 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -1.17 m/yr | 2 |
| Chlorophyll-a | → Stable | -0.1 µg/L/yr | 2 |
Ice Season
Historical ice data from Minnesota DNR (32 observations).
| Earliest | Latest | |
|---|---|---|
| Ice-Out | 2012-03-30 (2012) | 2013-05-17 (2013) |
| Ice-In | 2023-11-29 (2023) | 2019-12-02 (2019) |
Most recent ice-out: 2025-04-29
Location
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.
- ATamarack Bay LakeCass County · mi · Higher grade (B → A)
- BSugar LakeItasca County · mi · Higher overall water quality score
- BUpper Sucker LakeCass County · mi · Higher overall water quality score
- BSix Mile LakeCass County · mi · Higher overall water quality score
Nearby Lakes in Cass County
More Minnesota Lake Rankings
State Parks Near Lake Winnibigoshish
Other Grade B Lakes in Minnesota
Mesotrophic Lakes in Minnesota
Compare Lake Winnibigoshish With Nearby Lakes
DNR Fisheries Survey Summary
38 surveys on file from MN DNR Fisheries. Most recent: 2024-05-16 (Standard Survey).
Top Species by Catch Rate
| Species | Avg CPUE | Avg Weight |
|---|---|---|
| Yellow Perch | 227.14 | 0.19 lb |
| Spottail Shiner | 109.89 | — |
| MMS | 75.59 | — |
| Bluntnose Minnow | 22.18 | — |
| Walleye | 20.75 | 1.18 lb |
| SUN | 13.15 | — |
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
Walleye
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…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Lake Winnibigoshish. 4 reports on file.
- —Fisheries Lake Survey — WinnibigoshishFisheries Lake Survey · MN DNR LakeFinder
- —Aquatic Plant Report — Winnibigoshish (0702)Aquatic Plant Report · MN DNR LakeFinder
- —Fish Stocking History — WinnibigoshishFish Stocking History · MN DNR LakeFinder
- —Public Water Access Sites — WinnibigoshishPublic Water Access Sites · MN DNR LakeFinder
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