La Vallée-de-la-Gatineau County, Québec · Water Quality Report Card
Lac des Trente Et Un Milles
Lac des Trente Et Un Milles in La Vallée-de-la-Gatineau, Québec received a water quality grade of A (Excellent). Water clarity: 7.1 m visibility. Phosphorus: 3.8 µg/L. Chlorophyll-a (algae): 1 µg/L.
- Clarity
- 7.1 m
- Type
- Oligotrophic
Lac des Trente Et Un Milles is a cold, clear oligotrophic lake in La Vallée-de-la-Gatineau County, Québec. Water quality is graded A based on 3 sampling years through 2025. Compared to the 35 other monitored lakes in La Vallée-de-la-Gatineau County, Lac des Trente Et Un Milles ranks #10 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 23.3 ft down. Phosphorus level: 3.8 µg/L. Chlorophyll-a: 1 µg/L. Trophic State Index: 29.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 7.1 m | A |
| Phosphorus | 3.8 µg/L | A |
| Chlorophyll-a (Algae) | 1 µg/L | A |
| Trophic State Index (TSI) | 29 | Oligotrophic |
Low nutrients, clear water, excellent for swimming
Where to stay near Lac des Trente Et Un Milles
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Fishing Lac des Trente Et Un Milles
Location
County Ranking
Ranked #10 of 36 lakes in La Vallée-de-la-Gatineau
Nearby Lakes in La Vallée-de-la-Gatineau
Explore Lac des Trente Et Un Milles 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 Trente Et Un Milles 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: