L'Islet County, Québec · Water Quality Report Card
Lac Isidore
Lac Isidore in L'Islet, Québec received a water quality grade of C (Fair). Water clarity: 0.9 m visibility. Phosphorus: 20.9 µg/L. Chlorophyll-a (algae): 6.6 µg/L.
- Clarity
- 0.9 m
- Type
- Eutrophic
Lac Isidore is a productive, nutrient-rich eutrophic lake in L'Islet County, Québec. Water quality is graded C based on 3 sampling years through 2025. Compared to the 5 other monitored lakes in L'Islet County, Lac Isidore ranks #6 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
Generally safe for swimming, moderate water quality
Water Quality Grade: C, Fair
Very murky, less than 3 ft of visibility. Phosphorus level: 20.9 µg/L. Chlorophyll-a: 6.6 µg/L. Trophic State Index: 53.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 0.9 m | F |
| Phosphorus | 20.9 µg/L | B |
| Chlorophyll-a (Algae) | 6.6 µg/L | B |
| Trophic State Index (TSI) | 53 | Eutrophic |
High nutrients, frequent algae, reduced clarity
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Fishing Lac Isidore
Location
County Ranking
Ranked #6 of 6 lakes in L'Islet
Cleaner Lakes Within 30 Miles
Lac Isidore holds Grade C. 5 nearby lakes hold higher grades.
- ALac Fontaine ClaireL'Islet · 8 mi · Two grade letters higher (C → A)
- ALac BringéL'Islet · 10.8 mi · Two grade letters higher (C → A)
- BLac Trois SaumonsL'Islet · 12.4 mi · Higher grade (C → B)
- BLac JallyMontmagny · 13.8 mi · Higher grade (C → B)
- BLac MaillouxBellechasse · 21 mi · Higher grade (C → B)
Nearby Lakes in L'Islet
Explore Lac Isidore across LakeGrade
More Québec Lake Rankings
Other Grade C Lakes in Québec
Eutrophic Lakes in Québec
More records, surveys & data sources
Where this data comes from
Measurements for Lac Isidore 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: