Region of Waterloo County Lake Quality
Ontario, 5 lakes, average grade C (Fair)
Only 5 lakes in Region of Waterloo 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. Region of Waterloo 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.
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. Paradise Lake (B) is the cleanest in the county.
Quick Answers for Region of Waterloo County
Planning a trip? Check special fishing regulations for Paradise Lake — or check the official Ontario fishing regulations.
All Lakes in Region of Waterloo County
| Rank | Lake | Grade | Clarity | Phosphorus |
|---|---|---|---|---|
| 1 | Paradise Lake | B | 7.5 ft | 10.2 µg/L |
| 2 | Sunfish Lake | B | 9.2 ft | 9.4 µg/L |
| 3 | Barrie'S Lake | B | - | 23.7 µg/L |
| 4 | Four Wells Lake | C | 3.3 ft | 24 µg/L |
| 5 | Alder Lake | F | 1.6 ft | 147.5 µg/L |
Other Counties in Ontario
See how Region of Waterloo County stacks up in the national county water-quality rankings, or browse the full directory of graded lakes across all 38 states.
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Source: EPA National Aquatic Resource Surveys, 2026.