Milwaukee County Lake Quality
Wisconsin, 14 lakes, average grade C (Fair)
Milwaukee County has 14 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 average is C — the middle of the rubric, with one or two lakes pulling the average up or down depending on year.
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. Milwaukee Harbor Lake (C) is the cleanest in the county.
Quick Answers for Milwaukee County
Planning a trip? Check special fishing regulations for Milwaukee Harbor Lake, and the best times to fish — or browse the full Wisconsin regulations index.
All Lakes in Milwaukee County
| Rank | Lake | Grade | Clarity | Max Depth | Phosphorus |
|---|---|---|---|---|---|
| 1 | Milwaukee Harbor Lake | C | 8.2 ft | - | - |
| 2 | Lakeshore State Park Fish Shocking | C | 8 ft | - | - |
| 3 | Milwaukee Harbor Lake | C | 8.2 ft | - | - |
| 4 | Milwaukee Harbor Lake | C | 8.2 ft | - | - |
| 5 | New Zoo Pond | C | 7.6 ft | - | - |
| 6 | Milwaukee River Lake | C | 5.2 ft | - | - |
| 7 | Milwaukee Harbor North Half Lake | C | 7.2 ft | - | - |
| 8 | Milwaukee Harbor Lake | C | 7.4 ft | - | - |
| 9 | Milwaukee Harbor Lake | C | 6.6 ft | - | - |
| 10 | Milwaukee Harbor South Half Lake | D | 7.2 ft | - | - |
| 11 | Milwaukee Harbor Lake | D | 6.6 ft | - | - |
| 12 | Milwaukee Harbor Estuary Lake | D | 3.8 ft | - | - |
| 13 | Mallard Lake | D | 5 ft | 10 ft | - |
Source: EPA National Aquatic Resource Surveys, 2026.