Ralls County Lake Quality
Wisconsin, 4 lakes, average grade D (Poor)
Ralls 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. On average, Ralls County lakes grade D, with phosphorus loading and reduced clarity showing up across most of the dataset.
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 Mark Twain Lake by Hwy J (C); the most-stressed is Perry City Lake (F).
Quick Answers for Ralls County
Planning a trip? Check special fishing regulations for Mark Twain Lake by Hwy J, whether the fish are safe to eat, and the best times to fish — or browse the full Wisconsin regulations index.
All Lakes in Ralls County
| Rank | Lake | Grade | Clarity | Max Depth | Phosphorus |
|---|---|---|---|---|---|
| 1 | Mark Twain Lake by Hwy J | C | 3.7 ft | - | 33.6 µg/L |
| 2 | Mark Twain Lake Indian Creek Arm | C | 3.8 ft | - | 31.5 µg/L |
| 3 | Mark Twain Lake | D | 2.5 ft | - | 60.8 µg/L |
| 4 | Perry City Lake | F | - | - | 240 µg/L |
Source: EPA National Aquatic Resource Surveys, 2026.