Washington County Lake Quality
Wisconsin, 4 lakes, average grade B (Good)
Only 4 lakes in Washington 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. The county-wide average lands at B — solid water quality with most lakes carrying clear summer transparency and low-to-moderate phosphorus.
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. Wel-01 Lake (A) is the cleanest in the county.
Quick Answers for Washington County
Planning a trip? Check special fishing regulations for Wel-01 Lake, whether the fish are safe to eat, and the best times to fish — or browse the full Wisconsin regulations index.
All Lakes in Washington County
| Rank | Lake | Grade | Clarity | Max Depth | Phosphorus |
|---|---|---|---|---|---|
| 1 | Wel-01 Lake | A | 15.6 ft | - | - |
| 2 | Wem-09 Lake | A | 13 ft | - | - |
| 3 | Wem-08 Lake | A | 10 ft | - | - |
| 4 | Obs-07 Lake | F | 0.8 ft | - | - |
Source: EPA National Aquatic Resource Surveys, 2026.