Defiance County Lake Quality
Ohio, 2 lakes, average grade C (Fair)
Only 2 lakes in Defiance 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 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. Tiffin R Lake (C) is the cleanest in the county.
Quick Answers for Defiance County
Planning a trip? Check special fishing regulations for Tiffin R Lake — or check the official Ohio fishing regulations.
All Lakes in Defiance County
| Rank | Lake | Grade | Clarity | Phosphorus |
|---|---|---|---|---|
| 1 | Tiffin R Lake | C | - | 103.3 µg/L |
| 2 | Maumee R Upst Independence Dam Lake | D | - | 197.5 µg/L |
Other Counties in Ohio
See how Defiance County stacks up in the national county water-quality rankings, or browse the full directory of graded lakes across all 36 states and 2 Canadian provinces.
Where to stay near Defiance County
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Source: EPA National Aquatic Resource Surveys, 2026.