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. Rock River Lake (A) is the cleanest in the county.
Quick Answers for Rock County
Planning a trip? Check special fishing regulations for Rock River Lake, and the best times to fish — or browse the full Wisconsin regulations index.
DNR Reports (3)
Wisconsin DNR Fisheries Survey resources for lakes in Rock County. browse all reports →
- 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
| Rank | Lake | Grade | Clarity | Max Depth | Phosphorus |
|---|---|---|---|---|---|
| 1 | Rock River Lake | A | 21 ft | - | - |
| 2 | Clear Lake | A | 37.5 ft | - | - |
| 3 | Clear Lake | D | 2.8 ft | 12 ft | 38.5 µg/L |
| 4 | Leota Lake | D | 1.5 ft | 15 ft | 77 µg/L |
Source: EPA National Aquatic Resource Surveys, 2026.