Dufferin County Lake Quality
Ontario, 1 lakes, average grade A (Excellent)
Only 1 lakes in Dufferin 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. On average, Dufferin County lakes grade an A. That puts it near the top of the Ontario county ranking.
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. Island Lake (A) is the cleanest in the county.
Quick Answers for Dufferin County
Planning a trip? Check special fishing regulations for Island Lake — or check the official Ontario fishing regulations.
All Lakes in Dufferin County
| Rank | Lake | Grade | Clarity | Phosphorus |
|---|---|---|---|---|
| 1 | Island Lake | A | - | 14.8 µg/L |
Other Counties in Ontario
See how Dufferin 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 Dufferin County
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Source: EPA National Aquatic Resource Surveys, 2026.