Kosciusko County Lake Quality
Wisconsin, 19 lakes, average grade D (Poor)
There are 19 graded lakes in Kosciusko County. The mix is varied enough that the county-level average tells you the broad strokes, not the choose-this-cabin specifics. The county-wide average grade is D — water quality issues are persistent across most of the monitored basins. 7 lakes fall into the F bracket outright.
Most of the county's monitored lakes are shallow — under 50 feet — which means wind keeps the water column mixed all summer and sediment-bound phosphorus releases back into the surface layer whenever the bottom is disturbed. Dewart Lake (B) is the cleanest in the county.
Quick Answers for Kosciusko County
Planning a trip? Check special fishing regulations for Dewart Lake, whether the fish are safe to eat, and the best times to fish — or browse the full Wisconsin regulations index.
All Lakes in Kosciusko County
| Rank | Lake | Grade | Clarity | Max Depth | Phosphorus |
|---|---|---|---|---|---|
| 1 | Dewart Lake | B | 10.2 ft | - | - |
| 2 | Oswego Lake | B | 9.9 ft | - | - |
| 3 | Wti-02 Lake | B | 3.4 ft | - | - |
| 4 | Lmj-17 Lake | C | 6.4 ft | - | - |
| 5 | Big Chapman Lake | C | 6.9 ft | - | - |
| 6 | Tippecanoe Lake | C | 8.5 ft | - | - |
| 7 | Center Lake | C | 8.7 ft | - | - |
| 8 | Syracuse Lake | C | 8.8 ft | - | - |
| 9 | Wti-03 Lake | D | 1.7 ft | - | - |
| 10 | Lake Wawasee | D | 5.9 ft | - | - |
| 11 | Webster Lake | D | 5.6 ft | - | - |
| 12 | James Lake | D | 5.3 ft | - | - |
| 13 | Winona Lake | F | 2.8 ft | - | - |
| 14 | Yellow Creek Lake | F | 2.8 ft | - | - |
| 15 | Pike Lake | F | 1.9 ft | - | - |
| 16 | Beaver Dam Lake | F | 3.1 ft | - | - |
| 17 | Big Barbee Lake | F | 3.1 ft | - | - |
| 18 | Wae-05 Lake | F | 2.5 ft | - | - |
| 19 | Wti-04 Lake | F | 3.1 ft | - | - |
Source: EPA National Aquatic Resource Surveys, 2026.