Wellington County Lake Quality
Ontario, 6 lakes, average grade C (Fair)
Wellington County has 6 graded lakes — a thin enough sample that one or two stressed lakes can move the county average noticeably. Use the per-lake pages below for what actually matters. Wellington 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 Pike Lake (B); the most-stressed is Conestogo Lake (D).
Quick Answers for Wellington County
Planning a trip? Check special fishing regulations for Pike Lake — or check the official Ontario fishing regulations.
All Lakes in Wellington County
| Rank | Lake | Grade | Clarity | Phosphorus |
|---|---|---|---|---|
| 1 | Pike Lake | B | 9 ft | 11.8 µg/L |
| 2 | Belwood Lake | C | 4.6 ft | 22.6 µg/L |
| 3 | Puslinch Lake | C | 1 ft | 17.5 µg/L |
| 4 | Puslinch Lake | C | 6.2 ft | 28.1 µg/L |
| 5 | Guelph Lake | C | 2.6 ft | 24.6 µg/L |
| 6 | Conestogo Lake | D | 4.9 ft | 62.6 µg/L |
Other Counties in Ontario
See how Wellington 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 Wellington County
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Source: EPA National Aquatic Resource Surveys, 2026.