Dallas County Lake Quality
Wisconsin, 2 lakes, average grade C (Fair)
Dallas County has 2 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.
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 Dale Maffitt Reservoir (B); the most-stressed is Beaver Lake (F).
Quick Answers for Dallas County
Planning a trip? Check special fishing regulations for Dale Maffitt Reservoir, whether the fish are safe to eat, and the best times to fish — or browse the full Wisconsin regulations index.
All Lakes in Dallas County
| Rank | Lake | Grade | Clarity | Max Depth | Phosphorus |
|---|---|---|---|---|---|
| 1 | Dale Maffitt Reservoir | B | 9.8 ft | - | - |
| 2 | Beaver Lake | F | 1.9 ft | - | - |
Source: EPA National Aquatic Resource Surveys, 2026.