Rock County Lake Quality
Wisconsin, 4 lakes, average grade C (Fair)
Rock 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. The county average is C — the middle of the rubric, with one or two lakes pulling the average up or down depending on year.
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. Clear Lake (C) is the cleanest in the county.
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Quick Answers for Rock County
Planning a trip? Check special fishing regulations for Clear Lake, whether the fish are safe to eat, and the best times to fish — or browse the full Wisconsin regulations index.
Fishing in Rock County
DNR Reports (3)
Wisconsin DNR Fisheries Survey resources for lakes in Rock County. browse all reports →
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- 2025Rock River fall shocking survey, 2025Fisheries Survey · WI DNR · 2025 (PDF)
- 2025Turtle Creek smallmouth bass survey, 2025Fisheries Survey · WI DNR · 2025 (PDF)
- 2023Sugar River netting survey, 2023Netting Survey · WI DNR · 2023 (PDF)
All Lakes in Rock County
4 lakes · 2 graded, 2 not rated2 graded lakes · 2 not rated, hidden
| # | Lake | Grade | Clarity | Phosphorus | Algae | Trophic | Max Depth | Access |
|---|---|---|---|---|---|---|---|---|
| 1 | CClear LakeRock | C | 2.8 ft | 38.5 µg/L | No recent samples | No recent samples | 12 ft | ✓ Public |
| 2 | DLeota LakeRock | D | 1.5 ft | 77 µg/L | No recent samples | No recent samples | 15 ft | ✓ Public |
| NRRock River LakeRock | NR | 21 ft | No recent samples | No recent samples | No recent samples | No recent samples | ✓ Public | |
| NRClear LakeRock | NR | 37.5 ft | 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 Rock 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.