Allen County Lake Quality
Ohio, 7 lakes, average grade C (Fair)
Only 7 lakes in Allen 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. Lost Creek Reservoir (B) is the cleanest in the county.
Quick Answers for Allen County
Planning a trip? Check special fishing regulations for Lost Creek Reservoir — or check the official Ohio fishing regulations.
All Lakes in Allen County
| Rank | Lake | Grade | Clarity | Phosphorus |
|---|---|---|---|---|
| 1 | Lost Creek Reservoir | B | - | 26.5 µg/L |
| 2 | Ottawa R Lake | C | - | 207 µg/L |
| 3 | Ferguson Reservoir | C | - | 131 µg/L |
| 4 | Williams Reservoir | C | - | 39.4 µg/L |
| 5 | Metzger Reservoir | D | - | 70.4 µg/L |
| 6 | Twin Lakes Reservoir | D | - | 85.5 µg/L |
| 7 | Bresler Reservoir | F | - | 78.1 µg/L |
Other Counties in Ohio
See how Allen 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 Allen County
Top-rated places to stay near Allen County
Availability and prices from Stay22 partners (Booking.com, Vrbo, Expedia). We may earn a commission from bookings, at no extra cost to you.
Planning a trip to Allen County?
Get lake water-quality report cards plus the best cabin & lodging deals near Allen County — straight to your inbox. No spam, unsubscribe anytime.
Source: EPA National Aquatic Resource Surveys, 2026.