Suffolk County Lake Quality
Wisconsin, 5 lakes, average grade C (Fair)
Only 5 lakes in Suffolk 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. Suffolk 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. Little Long Pond (B) is the cleanest in the county.
Quick Answers for Suffolk County
Planning a trip? Check special fishing regulations for Little Long Pond, whether the fish are safe to eat, and the best times to fish — or browse the full Wisconsin regulations index.
All Lakes in Suffolk County
| Rank | Lake | Grade | Clarity | Max Depth | Phosphorus |
|---|---|---|---|---|---|
| 1 | Little Long Pond | B | 10 ft | - | - |
| 2 | Big Fresh Pond | C | 7.5 ft | - | - |
| 3 | Fresh Pond | D | 6.5 ft | - | - |
| 4 | Long Pond | D | 4 ft | - | - |
| 5 | Little Fresh Pond | D | 3.8 ft | - | - |
Source: EPA National Aquatic Resource Surveys, 2026.