Muskoka District County, Ontario · Water Quality Report Card
Prospect Lake
Prospect Lake in Muskoka District, Ontario received a water quality grade of B (Good). Water clarity: 3 m visibility. Phosphorus: 7.7 µg/L.
- Clarity
- 3 m
- Type
- Oligotrophic
Prospect 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, Prospect Lake ranks #122 for water quality.
Source: EPA Water Quality Portal sampling records, Ontario MECP, last sampled 2025-09-02. Grade methodology: LakeGrade methodology.
Watch Prospect Lake water quality
Subscribe for LakeQuality updates by email. No spam, unsubscribe anytime.
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: 7.7 µg/L. Trophic State Index: 39.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 3 m | C |
| Phosphorus | 7.7 µg/L | A |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 39 | Oligotrophic |
Low nutrients, clear water, excellent for swimming
Where to stay near Prospect Lake
Compare lakeside cabins, hotels, and vacation rentals near Prospect Lake in Muskoka District, Ontario — live availability and prices for your trip. Switch the map to Satellite to see the lake and how close each stay is to the water.
Top-rated places to stay near Prospect Lake
Availability and prices from Stay22 partners (Booking.com, Vrbo, Expedia). We may earn a commission from bookings, at no extra cost to you.
Planning a trip to Prospect Lake?
Get lake water-quality report cards plus the best cabin & lodging deals near Prospect Lake — straight to your inbox. No spam, unsubscribe anytime.
Fishing Prospect Lake
Location
County Ranking
Ranked #122 of 170 lakes in Muskoka District
Cleaner Lakes Within 30 Miles
Prospect Lake holds Grade B. 4 nearby lakes hold higher grades.
- ASpring LakeMuskoka District · 1.6 mi · Higher grade (B → A)
- AWood LakeMuskoka District · 3.4 mi · Higher grade (B → A)
- ALeech LakeMuskoka District · 4.7 mi · Higher grade (B → A)
- AFrau LakeMuskoka District · 5.5 mi · Higher grade (B → A)
Nearby Lakes in Muskoka District
Explore Prospect 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 Prospect 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: 2025-09-02
Monitoring stations: