Mason County Lake Quality
Wisconsin, 8 lakes, average grade B (Good)
Mason County has 8 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-wide average lands at B — solid water quality with most lakes carrying clear summer transparency and low-to-moderate phosphorus.
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 Chancellor Lake (A); the most-stressed is Upper Hamlin Lake West Basin East of the Narrows (C).
Quick Answers for Mason County
Planning a trip? Check special fishing regulations for Chancellor Lake, whether the fish are safe to eat, and the best times to fish — or browse the full Wisconsin regulations index.
All Lakes in Mason County
| Rank | Lake | Grade | Clarity | Max Depth | Phosphorus |
|---|---|---|---|---|---|
| 1 | Chancellor Lake | A | 26 ft | - | - |
| 2 | Mi34 Lake | A | 49.9 ft | - | - |
| 3 | Chancellor Lake Central Basin | A | 25 ft | - | - |
| 4 | Gun Lake Central Basin; Freesoil Township | A | 14 ft | - | - |
| 5 | Lower Hamlin Lake North Central Basin South of the Narrows | A | 13.5 ft | - | - |
| 6 | Hamlin Lake | B | 10 ft | - | - |
| 7 | Gun Lake | B | 14 ft | - | - |
| 8 | Upper Hamlin Lake West Basin East of the Narrows | C | 6.5 ft | - | - |
Source: EPA National Aquatic Resource Surveys, 2026.