Muskoka District County, Ontario · Water Quality Report Card
North Muldrew Lake
North Muldrew Lake in Muskoka District, Ontario received a water quality grade of B (Good). Water clarity: 3 m visibility. Phosphorus: 8.9 µg/L.
- Clarity
- 3 m
- Type
- Oligotrophic
North Muldrew Lake is a cold, clear oligotrophic lake in Muskoka District County, Ontario. Water quality is graded B based on 2 sampling years through 2025. Compared to the 169 other monitored lakes in Muskoka District County, North Muldrew Lake ranks #118 for water quality.
Source: EPA Water Quality Portal sampling records, Ontario MECP, last sampled 2025-10-05. Grade methodology: LakeGrade methodology.
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Swimming Safety
Good for swimming, clear water with low algae levels
Water Quality Grade: B, Good
Moderate clarity, visible to about 9.8 ft. Phosphorus level: 8.9 µg/L. Trophic State Index: 40.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 3 m | C |
| Phosphorus | 8.9 µg/L | A |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 40 | Oligotrophic |
Low nutrients, clear water, excellent for swimming
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Fishing North Muldrew Lake
Location
County Ranking
Ranked #118 of 170 lakes in Muskoka District
Cleaner Lakes Within 30 Miles
North Muldrew Lake holds Grade B. 5 nearby lakes hold higher grades.
- ADeer LakeMuskoka District · 2.9 mi · Higher grade (B → A)
- ALong Turtle LakeMuskoka District · 0.8 mi · Higher grade (B → A)
- ATurtle LakeMuskoka District · 0.8 mi · Higher grade (B → A)
- ALoon LakeMuskoka District · 1.3 mi · Higher grade (B → A)
- APine LakeMuskoka District · 1.8 mi · Higher grade (B → A)
Nearby Lakes in Muskoka District
Explore North Muldrew Lake across LakeGrade
More Ontario Lake Rankings
Other Grade B Lakes in Ontario
Oligotrophic Lakes in Ontario
More records, surveys & data sources
Where this data comes from
Measurements for North Muldrew Lake 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: 2025-10-05
Monitoring stations: