Is Lac Trois Milles safe to swim in?

Good for swimming, clear water with low algae levels. Lac Trois Milles has an overall water quality grade of B. Algae concentration (chlorophyll-a) is 3.3 µg/L. Always check local health department advisories before swimming.

Mékinac County, Québec · Water Quality Report Card

Lac Trois Milles

Grade B — Good

Mesotrophic

Lac Trois Milles in Mékinac, Québec received a water quality grade of B (Good). Water clarity: 2.6 m visibility. Phosphorus: 8.4 µg/L. Chlorophyll-a (algae): 3.3 µg/L.

Clarity: 2.6 m
Type: Mesotrophic

Where to stay →Safe to swim?

Lac Trois Milles is a mesotrophic lake in Mékinac County, Québec. Water quality is graded B based on 3 sampling years through 2025. Compared to the 24 other monitored lakes in Mékinac County, Lac Trois Milles ranks #19 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

Good for swimming, clear water with low algae levels

Water Quality Grade: B, Good

Moderate clarity, visible to about 8.5 ft. Phosphorus level: 8.4 µg/L. Chlorophyll-a: 3.3 µg/L. Trophic State Index: 41.

Metric	Value	Grade
Water Clarity (Secchi Depth)	2.6 m	C
Phosphorus	8.4 µg/L	A
Chlorophyll-a (Algae)	3.3 µg/L	A
Trophic State Index (TSI)	41	Mesotrophic

Moderate nutrients, good water quality

Where to stay near Lac Trois Milles

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Fishing Lac Trois Milles

→ Lac Trois Milles fishing regulations (limits, seasons, special rules)

Location

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County Ranking

Ranked #19 of 25 lakes in Mékinac

Cleaner Lakes Within 30 Miles

Lac Trois Milles holds Grade B. 5 nearby lakes hold higher grades.

See full comparison →

Nearby Lakes in Mékinac

Explore Lac Trois Milles across LakeGrade

Lake Fishing Forecast

Species activity outlook by water temperature and season

Mesotrophic Lakes

Moderate nutrients, good water quality

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Grade A/B + low algae filter

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Other Grade B Lakes in Québec

Portneuf · 2.3 m

Portneuf · 2.9 m

Portneuf · 4.1 m

Portneuf · 1.4 m

Portneuf · 2.9 m

Portneuf · 3 m

Mesotrophic Lakes in Québec

Lac à la Hache Lac Chat Lac de L'Oasis Lac à la Tortue

More records, surveys & data sources

Where this data comes from

Measurements for Lac Trois 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:

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