Allegan County Lake Quality
Wisconsin, 12 lakes, average grade C (Fair)
Only 12 lakes in Allegan 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. Allegan 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.
The county's lakes lean shallow, which makes the grades sensitive to wind, sediment-resuspension, and any nutrient inputs from the watershed. The cleanest lake on the books is Mi18m Lake (A); the most-stressed is Swan Lake West Central Basin,Cheshire Township (F).
Quick Answers for Allegan County
Planning a trip? Check special fishing regulations for Mi18m Lake, whether the fish are safe to eat, and the best times to fish — or browse the full Wisconsin regulations index.
All Lakes in Allegan County
| Rank | Lake | Grade | Clarity | Max Depth | Phosphorus |
|---|---|---|---|---|---|
| 1 | Mi18m Lake | A | 45.1 ft | - | - |
| 2 | Mi48b Lake | A | - | - | - |
| 3 | Eagle Lake North Central Basin | A | 14 ft | - | - |
| 4 | Eagle Lake | B | 14 ft | - | - |
| 5 | Miner Lake West Central Basin,Allegan Township | B | 10.5 ft | - | - |
| 6 | Ingerson Lake | B | 9 ft | - | 41.5 µg/L |
| 7 | Osterhout Lake | C | 9 ft | - | - |
| 8 | Osterhout Lake Northern Basin | C | 8.5 ft | - | - |
| 9 | Green Lake | C | 8 ft | - | - |
| 10 | Green Lake Southwest Basin; Leighton Township | C | 8 ft | - | - |
| 11 | Moore Lake | C | 6.2 ft | - | 38 µg/L |
| 12 | Swan Lake West Central Basin,Cheshire Township | F | 3 ft | - | - |
Source: EPA National Aquatic Resource Surveys, 2026.