Leeds and Grenville Counties County, Ontario · Water Quality Report Card
South Lake
South Lake in Leeds and Grenville Counties, Ontario received a water quality grade of C (Fair). Water clarity: 1.5 m visibility. Phosphorus: 26.1 µg/L.
- Clarity
- 1.5 m
- Type
- Eutrophic
South Lake is a productive, nutrient-rich eutrophic lake in Leeds and Grenville Counties County, Ontario. Water quality is graded C based on 2 sampling years through 2025. Compared to the 33 other monitored lakes in Leeds and Grenville Counties County, South Lake ranks #33 for water quality.
Source: EPA Water Quality Portal sampling records, Ontario MECP, last sampled 2025-07-19. Grade methodology: LakeGrade methodology.
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Swimming Safety
Generally safe for swimming, moderate water quality
Water Quality Grade: C, Fair
Murky, only visible to about 4.9 ft. Phosphorus level: 26.1 µg/L. Trophic State Index: 53.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 1.5 m | D |
| Phosphorus | 26.1 µg/L | B |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 53 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Where to stay near South Lake
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Fishing South Lake
Location
County Ranking
Ranked #33 of 34 lakes in Leeds and Grenville Counties
Cleaner Lakes Within 30 Miles
South Lake holds Grade C. 5 nearby lakes hold higher grades.
- AGananoque LakeLeeds and Grenville Counties · 5.2 mi · Two grade letters higher (C → A)
- AWhitefish LakeLeeds and Grenville Counties · 5.6 mi · Two grade letters higher (C → A)
- AGananoque River LakeLeeds and Grenville Counties · 6 mi · Two grade letters higher (C → A)
- AGrippen LakeLeeds and Grenville Counties · 6 mi · Two grade letters higher (C → A)
- BCranberry LakeFrontenac · 3.6 mi · Higher grade (C → B)
Nearby Lakes in Leeds and Grenville Counties
Explore South Lake across LakeGrade
More Ontario Lake Rankings
Other Grade C Lakes in Ontario
Eutrophic Lakes in Ontario
More records, surveys & data sources
Where this data comes from
Measurements for South 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: 2025-07-19
Monitoring stations: