York Region County Lake Quality
Ontario, 11 lakes, average grade B (Good)
York Region County has 11 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. With an average grade of B, York Region 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. Haynes Lake (A) is the cleanest in the county.
Quick Answers for York Region County
Planning a trip? Check special fishing regulations for Haynes Lake — or check the official Ontario fishing regulations.
All Lakes in York Region County
| Rank | Lake | Grade | Clarity | Phosphorus |
|---|---|---|---|---|
| 1 | Haynes Lake | A | - | 12.9 µg/L |
| 2 | Eaton Lake | A | 10.5 ft | 18.9 µg/L |
| 3 | Mary Lake | A | 10.7 ft | 17 µg/L |
| 4 | Preston Lake | A | 13.1 ft | 15 µg/L |
| 5 | Musselmans Lake | B | 12 ft | - |
| 6 | Simoen Lake | B | 12.5 ft | - |
| 7 | St George Lake | B | 9.7 ft | 18.7 µg/L |
| 8 | Wilcox Lake | B | 8 ft | 18.8 µg/L |
| 9 | Bond Lake | B | - | 23.7 µg/L |
| 10 | Musselman Lake | B | 7.2 ft | 20.6 µg/L |
| 11 | Clarke Lake | D | 4.3 ft | - |
Other Counties in Ontario
See how York Region 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 York Region County
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Source: EPA National Aquatic Resource Surveys, 2026.