Clark County Lake Quality
Wisconsin, 2 lakes, average grade B (Good)
Only 2 lakes in Clark County carry an active grade. The county-level summary is therefore representative of those specific lakes, not necessarily of every water body in the county. With an average grade of B, Clark County sits comfortably above the Missouri 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 Fox Valley Lake (B); the most-stressed is Lake of the Oaks (C).
Quick Answers for Clark County
Planning a trip? Check special fishing regulations for Fox Valley Lake, whether the fish are safe to eat, and the best times to fish — or browse the full Wisconsin regulations index.
All Lakes in Clark County
| Rank | Lake | Grade | Clarity | Max Depth | Phosphorus |
|---|---|---|---|---|---|
| 1 | Fox Valley Lake | B | 8.5 ft | - | 16.5 µg/L |
| 2 | Lake of the Oaks | C | - | - | 47 µg/L |
Source: EPA National Aquatic Resource Surveys, 2026.