Jefferson County Lake Quality
Wisconsin, 7 lakes, average grade C (Fair)
Only 7 lakes in Jefferson County carry an active grade. The county-level summary is therefore representative of those specific lakes, not necessarily of every water body in the county. Jefferson County averages to a C. The distribution behind that average matters more than the letter: a few stressed lakes versus many decent ones can produce the same average as the inverse.
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. Lake Wauwanoka Nr. Dam (A) is the cleanest in the county.
Quick Answers for Jefferson County
Planning a trip? Check special fishing regulations for Lake Wauwanoka Nr. Dam, whether the fish are safe to eat, and the best times to fish — or browse the full Wisconsin regulations index.
All Lakes in Jefferson County
| Rank | Lake | Grade | Clarity | Max Depth | Phosphorus |
|---|---|---|---|---|---|
| 1 | Lake Wauwanoka Nr. Dam | A | 12.9 ft | - | 8 µg/L |
| 2 | Cattails 2 Lake | A | - | - | 24 µg/L |
| 3 | Cole Lake | B | 18.5 ft | - | 17 µg/L |
| 4 | Cattails 1 Lake | B | 6.3 ft | - | 16 µg/L |
| 5 | Lake Tishomingo Nr. Dam | C | 5.4 ft | - | 23.5 µg/L |
| 6 | Cedar Hill Lake 1 | D | 2.6 ft | - | 54.3 µg/L |
| 7 | Fon-du-Lac Reservoir | F | 1.3 ft | - | 81 µg/L |
Source: EPA National Aquatic Resource Surveys, 2026.