Central Ontario County Lake Quality
Ontario, 20 lakes, average grade B (Good)
Central Ontario County's 20 graded lakes fall in the moderate-density bracket for Ontario. The county-level average smooths over real differences — a single agricultural watershed near the southwest corner can pull the average down even if the rest of the county runs clean. With an average grade of B, Central Ontario County sits comfortably above the Ontario median.
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. Four Mile Lake (A) is the cleanest in the county.
Quick Answers for Central Ontario County
Planning a trip? Check special fishing regulations for Four Mile Lake — or check the official Ontario fishing regulations.
All Lakes in Central Ontario County
| Rank | Lake | Grade | Clarity | Phosphorus |
|---|---|---|---|---|
| 1 | Four Mile Lake | A | 21.3 ft | 5.9 µg/L |
| 2 | Little Lake | A | 16.2 ft | - |
| 3 | Oak Lake | A | 17.1 ft | 13.3 µg/L |
| 4 | Young Lake | A | 20.3 ft | 9.9 µg/L |
| 5 | Balsam Lake | A | 14.1 ft | 11.3 µg/L |
| 6 | Cameron Lake | A | 11.8 ft | 10.1 µg/L |
| 7 | Crego Lake | A | 11.8 ft | 8.8 µg/L |
| 8 | Logan Lake | A | 10.5 ft | 8.7 µg/L |
| 9 | Rush Lake | A | 11.2 ft | 8.9 µg/L |
| 10 | Shadow Lake | A | 13.8 ft | 6.3 µg/L |
| 11 | Silver Lake | A | 12.3 ft | 7.5 µg/L |
| 12 | Head Lake | B | 9.8 ft | 11.4 µg/L |
| 13 | Sturgeon Lake | B | 9.5 ft | 16.1 µg/L |
| 14 | Canal Lake | B | 6.6 ft | 18.8 µg/L |
| 15 | Cranberry Lake | B | 6.2 ft | 17 µg/L |
| 16 | Dalrymple Lake | B | 6.4 ft | 15.8 µg/L |
| 17 | Mitchell Lake | B | 7.1 ft | 21.9 µg/L |
| 18 | Pigeon River Lake | B | 6.9 ft | 22.9 µg/L |
| 19 | Emily Lake | C | 9.5 ft | 30.4 µg/L |
| 20 | Scugog Lake | C | 3.1 ft | 20.9 µg/L |
Other Counties in Ontario
See how Central Ontario County stacks up in the national county water-quality rankings, or browse the full directory of graded lakes across all 38 states.
Where to stay near Central Ontario County
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Source: EPA National Aquatic Resource Surveys, 2026.