Winnebago County Lake Quality
Wisconsin, 5 lakes, average grade F (Very Poor)
Winnebago County has 5 graded lakes — a thin enough sample that one or two stressed lakes can move the county average noticeably. Use the per-lake pages below for what actually matters. The county average is F — the most-stressed bracket in our rubric. Most monitored lakes here show persistent nutrient loading and algal pressure.
Most of the county's monitored lakes are shallow — under 50 feet — which means wind keeps the water column mixed all summer and sediment-bound phosphorus releases back into the surface layer whenever the bottom is disturbed. Rush Lake (C) is the cleanest in the county.
Quick Answers for Winnebago County
Planning a trip? Check special fishing regulations for Rush Lake, whether the fish are safe to eat, and the best times to fish — or browse the full Wisconsin regulations index.
DNR Reports (8)
Wisconsin DNR Fisheries Survey resources for lakes in Winnebago County. browse all reports →
- 2025Community Park Ponds spring shocking survey, 2025Spring Shocking Survey · WI DNR · 2025 (PDF)
- 2025Ken Robl Pond spring shocking survey, 2025Spring Shocking Survey · WI DNR · 2025 (PDF)
- 2025Lake Winnebago bottom trawling assessment report, 2025Fisheries Survey · WI DNR · 2025 (PDF)
- 2025Winnebago System chironomid assessment report, 2025Fisheries Survey · WI DNR · 2025 (PDF)
- 2025Winnebago System sturgeon spawning and population assessment report 2025Fisheries Survey · WI DNR · 2025 (PDF)
- 2023Fond du Lac River and Van Dyne Creek fish passage study, 2023Fisheries Survey · WI DNR · 2023 (PDF)
- 2023Sunset Bay (Lake Butte des Morts) spring shocking survey, 2023Spring Shocking Survey · WI DNR · 2023 (PDF)
- 2023Winnebago System lake sturgeon acoustic telemetry report 2023Fisheries Survey · WI DNR · 2023 (PDF)
All Lakes in Winnebago County
| Rank | Lake | Grade | Clarity | Max Depth | Phosphorus |
|---|---|---|---|---|---|
| 1 | Rush Lake | C | 3.2 ft | 5 ft | 26 µg/L |
| 2 | Lake Winneconne | F | 2.4 ft | 9 ft | - |
| 3 | Lake Butte des Morts | F | 2.3 ft | 9 ft | - |
| 4 | Lake Poygan | F | 2.5 ft | 11 ft | - |
| 5 | Little Lake Butte des Morts | F | 2 ft | 18 ft | 133.5 µg/L |
Source: EPA National Aquatic Resource Surveys, 2026.