Ottawa County Lake Quality
Wisconsin, 5 lakes, average grade C (Fair)
Only 5 lakes in Ottawa 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. Ottawa 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. Mi19 Lake (A) is the cleanest in the county.
Quick Answers for Ottawa County
Planning a trip? Check special fishing regulations for Mi19 Lake, whether the fish are safe to eat, and the best times to fish — or browse the full Wisconsin regulations index.
All Lakes in Ottawa County
| Rank | Lake | Grade | Clarity | Max Depth | Phosphorus |
|---|---|---|---|---|---|
| 1 | Mi19 Lake | A | 37.1 ft | - | - |
| 2 | Mi46b Lake | A | - | - | - |
| 3 | Crockery Lake Southwest Basin; Chester Township | C | 4 ft | - | - |
| 4 | Crockery Lake | D | 3.5 ft | - | - |
| 5 | Crockery Lake Northeast Basin; Chester Township | F | 3 ft | - | - |
Source: EPA National Aquatic Resource Surveys, 2026.