Parry Sound District County, Ontario · Water Quality Report Card
Blackstone Lake
Blackstone Lake in Parry Sound District, Ontario received a water quality grade of A (Excellent). Water clarity: 4.6 m visibility. Phosphorus: 8.9 µg/L.
- Clarity
- 4.6 m
- Type
- Oligotrophic
Blackstone Lake is a cold, clear oligotrophic lake in Parry Sound District County, Ontario. Water quality is graded A based on 2 sampling years through 2025. Compared to the 230 other monitored lakes in Parry Sound District County, Blackstone Lake ranks #3 for water quality.
Source: EPA Water Quality Portal sampling records, Ontario MECP, last sampled 2025-10-09. Grade methodology: LakeGrade methodology.
Watch Blackstone Lake water quality
Subscribe for LakeQuality updates by email. No spam, unsubscribe anytime.
Swimming Safety
Excellent for swimming, crystal clear water with minimal algae
Water Quality Grade: A, Excellent
Crystal clear, you can see 15.1 ft down. Phosphorus level: 8.9 µg/L. Trophic State Index: 37.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 4.6 m | A |
| Phosphorus | 8.9 µg/L | A |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 37 | Oligotrophic |
Low nutrients, clear water, excellent for swimming
Where to stay near Blackstone Lake
Compare lakeside cabins, hotels, and vacation rentals near Blackstone Lake in Parry Sound 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 Blackstone 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 Blackstone Lake?
Get lake water-quality report cards plus the best cabin & lodging deals near Blackstone Lake — straight to your inbox. No spam, unsubscribe anytime.
Fishing Blackstone Lake
Location
County Ranking
Ranked #3 of 231 lakes in Parry Sound District
Nearby Lakes in Parry Sound District
Explore Blackstone Lake 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 Blackstone 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: 2025-10-09
Monitoring stations: