Winnebago County Lake Quality
Wisconsin, 5 lakes, average grade C (Fair)
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. Winnebago County averages to a C. The distribution behind that average matters more than the letter: a few stressed lakes versus many decent ones can produce the same average as the inverse.
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 (B) is the cleanest in the county.
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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.
Fishing in Winnebago County
DNR Reports (8)
Wisconsin DNR Fisheries Survey resources for lakes in Winnebago County. browse all reports →
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- 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
5 lakes · 2 graded, 3 not rated2 graded lakes · 3 not rated, hidden
| # | Lake | Grade | Clarity | Phosphorus | Algae | Trophic | Max Depth | Access |
|---|---|---|---|---|---|---|---|---|
| 1 | BRush LakeWinnebago | B | 3.2 ft | 26 µg/L | No recent samples | No recent samples | 5 ft | ✓ Public |
| 2 | DLittle Lake Butte des MortsWinnebago | D | 2 ft | 133.5 µg/L | No recent samples | No recent samples | 18 ft | ✓ Public |
| NRLake WinneconneWinnebago | NR | 2.5 ft | No recent samples | No recent samples | No recent samples | 9 ft | ✓ Public | |
| NRLake Butte des MortsWinnebago | NR | 2.3 ft | No recent samples | No recent samples | No recent samples | 9 ft | ✓ Public | |
| NRLake PoyganWinnebago | NR | 2.5 ft | No recent samples | No recent samples | No recent samples | 11 ft | ✓ Public |
NR = not rated: the monitoring record does not meet the evidence bar for a grade. That is EPA Integrated Reporting Category 3 (insufficient information), not a failing grade. How grading works.
Lake Match
Which lake suits how you actually use one?
Six questions — swimming, fishing, quiet, cabins, drive time — and a shortlist of graded lakes that fit, with the water quality behind each one.
Other Counties in Wisconsin
See how Winnebago County stacks up in the national county water-quality rankings, or browse the full directory of graded lakes across all 39 states and 2 Canadian provinces.
Source: EPA National Aquatic Resource Surveys, 2026.