Brown County Lake Quality
Wisconsin, 4 lakes, average grade B (Good)
Brown County has 4 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. With an average grade of B, Brown County sits comfortably above the Wisconsin median.
The county's lakes lean shallow, which makes the grades sensitive to wind, sediment-resuspension, and any nutrient inputs from the watershed. The cleanest lake on the books is Quarry Lake (B); the most-stressed is Osnuhsa Lake (C).
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Quick Answers for Brown County
Planning a trip? Check special fishing regulations for Quarry Lake — or browse the full Wisconsin regulations index.
DNR Reports (4)
Wisconsin DNR Fisheries Survey resources for lakes in Brown County. browse all reports →
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- 2021Status of Great Lakes Musky in Green Bay, 2021Musky Survey · WI DNR · 2021 (PDF)
- 2021Status of walleye in Southern Green Bay, 2021Walleye Survey · WI DNR · 2021 (PDF)
- 2018Green Bay walleye tagging survey, 2018Walleye Survey · WI DNR · 2018 (PDF)
- 2015Green Bay walleye tagging survey, 2015Walleye Survey · WI DNR · 2015 (PDF)
All Lakes in Brown County
4 lakes · 2 graded, 2 not rated2 graded lakes · 2 not rated, hidden
| # | Lake | Grade | Clarity | Phosphorus | Algae | Trophic | Max Depth | Access |
|---|---|---|---|---|---|---|---|---|
| 1 | BQuarry LakeBrown | B | 8 ft | 34 µg/L | 9.6 µg/L | No recent samples | No recent samples | Not recorded |
| 2 | COsnuhsa LakeBrown | C | 5.6 ft | 63.5 µg/L | 9.9 µg/L | No recent samples | No recent samples | Not recorded |
| NRLily LakeBrown | NR | 9.6 ft | No recent samples | No recent samples | No recent samples | 19 ft | ✓ Public | |
| NRLgb LakeBrown | NR | No recent samples | No recent samples | No recent samples | No recent samples | No recent samples | Not recorded |
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 Brown 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.