Muskoka District County, Ontario · Water Quality Report Card
Lake of Bays
Lake of Bays in Muskoka District, Ontario received a water quality grade of A (Excellent). Water clarity: 5.5 m visibility. Phosphorus: 6 µg/L.
- Clarity
- 5.5 m
- Type
- Oligotrophic
Lake of Bays is a cold, clear oligotrophic lake in Muskoka District County, Ontario. Water quality is graded A based on 2 sampling years through 2025. Compared to the 169 other monitored lakes in Muskoka District County, Lake of Bays ranks #13 for water quality.
Source: EPA Water Quality Portal sampling records, Ontario MECP, last sampled 2025-10-12. Grade methodology: LakeGrade methodology.
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Swimming Safety
Excellent for swimming, crystal clear water with minimal algae
Water Quality Grade: A, Excellent
Crystal clear, you can see 18 ft down. Phosphorus level: 6 µg/L. Trophic State Index: 33.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 5.5 m | A |
| Phosphorus | 6 µg/L | A |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 33 | Oligotrophic |
Low nutrients, clear water, excellent for swimming
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Fishing Lake of Bays
Location
County Ranking
Ranked #13 of 170 lakes in Muskoka District
Nearby Lakes in Muskoka District
Explore Lake of Bays across LakeGrade
More Ontario Lake Rankings
Other Grade A Lakes in Ontario
Oligotrophic Lakes in Ontario
More records, surveys & data sources
Where this data comes from
Measurements for Lake of Bays come from the EPA Water Quality Portal. Per-sample source details are not recorded for this lake.
Data Sources
Water quality data from the EPA Water Quality Portal
Grade thresholds from the EPA National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion
Most recent sample: 2025-10-12
Monitoring stations: