Herkimer County Lake Quality
Wisconsin, 7 lakes, average grade A (Excellent)
Herkimer County has 7 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's average grade is A — among the cleanest in New York. 6 lakes pull an A on their own, and almost none fall into the D or F brackets.
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 South Lake (A); the most-stressed is Fulton Chain Lakes (B).
Quick Answers for Herkimer County
Planning a trip? Check special fishing regulations for South Lake, whether the fish are safe to eat, and the best times to fish — or browse the full Wisconsin regulations index.
All Lakes in Herkimer County
| Rank | Lake | Grade | Clarity | Max Depth | Phosphorus |
|---|---|---|---|---|---|
| 1 | South Lake | A | - | - | 4 µg/L |
| 2 | West Pond | A | - | - | 10 µg/L |
| 3 | Squash Pond | A | - | - | 11 µg/L |
| 4 | Windfall Pond | A | - | - | 9 µg/L |
| 5 | Loon Hollows Pond | A | - | - | 5 µg/L |
| 6 | Willys Lake | A | - | - | 4 µg/L |
| 7 | Fulton Chain Lakes | B | 10.3 ft | - | - |
Source: EPA National Aquatic Resource Surveys, 2026.