Nipissing District County, Ontario · Water Quality Report Card
Mercer Lake
Mercer Lake in Nipissing District, Ontario received a water quality grade of C (Fair). Water clarity: 1.4 m visibility. Phosphorus: 21.5 µg/L.
- Clarity
- 1.4 m
- Type
- Eutrophic
Mercer Lake is a productive, nutrient-rich eutrophic lake in Nipissing District County, Ontario. Water quality is graded C based on 2 sampling years through 2025. Compared to the 280 other monitored lakes in Nipissing District County, Mercer Lake ranks #271 for water quality.
Source: EPA Water Quality Portal sampling records, Ontario MECP, 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
Murky, only visible to about 4.6 ft. Phosphorus level: 21.5 µg/L. Trophic State Index: 52.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 1.4 m | D |
| Phosphorus | 21.5 µg/L | B |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 52 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Where to stay near Mercer Lake
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Fishing Mercer Lake
Location
County Ranking
Ranked #271 of 281 lakes in Nipissing District
Cleaner Lakes Within 30 Miles
Mercer Lake holds Grade C. 5 nearby lakes hold higher grades.
- ATrout LakeSudbury District · 14.8 mi · Two grade letters higher (C → A)
- BWaterclear L. LakeParry Sound District · 12 mi · Higher grade (C → B)
- BFrench River LakeSudbury District · 14.5 mi · Higher grade (C → B)
- BDollars LakeParry Sound District · 15.3 mi · Higher grade (C → B)
- BMarshall LakeNipissing District · 3.4 mi · Higher grade (C → B)
Nearby Lakes in Nipissing District
Explore Mercer 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 Mercer 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: 2025-08-01
Monitoring stations: