Les Laurentides County, Québec · Water Quality Report Card
Lac des Trois Montagnes
Lac des Trois Montagnes in Les Laurentides, Québec received a water quality grade of A (Excellent). Water clarity: 7.2 m visibility. Phosphorus: 3 µg/L. Chlorophyll-a (algae): 1.1 µg/L.
- Clarity
- 7.2 m
- Type
- Oligotrophic
Lac des Trois Montagnes is a cold, clear oligotrophic lake in Les Laurentides County, Québec. Water quality is graded A based on 3 sampling years through 2025. Compared to the 118 other monitored lakes in Les Laurentides County, Lac des Trois Montagnes ranks #2 for water quality.
Source: EPA Water Quality Portal sampling records, MELCCFP, last sampled 2025-08-01. 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 23.6 ft down. Phosphorus level: 3 µg/L. Chlorophyll-a: 1.1 µg/L. Trophic State Index: 27.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 7.2 m | A |
| Phosphorus | 3 µg/L | A |
| Chlorophyll-a (Algae) | 1.1 µg/L | A |
| Trophic State Index (TSI) | 27 | Oligotrophic |
Low nutrients, clear water, excellent for swimming
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Fishing Lac des Trois Montagnes
Location
County Ranking
Ranked #2 of 119 lakes in Les Laurentides
Nearby Lakes in Les Laurentides
Explore Lac des Trois Montagnes across LakeGrade
More Québec Lake Rankings
Other Grade A Lakes in Québec
Oligotrophic Lakes in Québec
More records, surveys & data sources
Where this data comes from
Measurements for Lac des Trois Montagnes 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: 2025-08-01
Monitoring stations: