Pontiac County, Québec · Water Quality Report Card
Lac Thompson
Lac Thompson in Pontiac, Québec received a water quality grade of A (Excellent). Water clarity: 6.2 m visibility.
- Clarity
- 6.2 m
- Type
- Oligotrophic
Lac Thompson is a cold, clear oligotrophic lake in Pontiac County, Québec. Water quality is graded A based on 1 sampling years through 2025. Compared to the 17 other monitored lakes in Pontiac County, Lac Thompson ranks #13 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 20.3 ft down. Trophic State Index: 34.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 6.2 m | A |
| Phosphorus | No data | |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 34 | Oligotrophic |
Low nutrients, clear water, excellent for swimming
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Fishing Lac Thompson
Location
County Ranking
Ranked #13 of 18 lakes in Pontiac
Nearby Lakes in Pontiac
Explore Lac Thompson 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 Thompson 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: