Is Lac de la Grande Fourche safe to swim in?

Good for swimming, clear water with low algae levels. Lac de la Grande Fourche has an overall water quality grade of B. Algae concentration (chlorophyll-a) is 6.2 µg/L. Always check local health department advisories before swimming.

Rivière-du-Loup County, Québec · Water Quality Report Card

Lac de la Grande Fourche

Grade B — Good

Mesotrophic

Lac de la Grande Fourche in Rivière-du-Loup, Québec received a water quality grade of B (Good). Water clarity: 2.2 m visibility. Phosphorus: 13 µg/L. Chlorophyll-a (algae): 6.2 µg/L.

Clarity: 2.2 m
Type: Mesotrophic

Where to stay →Safe to swim?

Lac de la Grande Fourche is a mesotrophic lake in Rivière-du-Loup County, Québec. Water quality is graded B based on 3 sampling years through 2025. Compared to the 2 other monitored lakes in Rivière-du-Loup County, Lac de la Grande Fourche ranks #3 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 7.2 ft. Phosphorus level: 13 µg/L. Chlorophyll-a: 6.2 µg/L. Trophic State Index: 46.

Metric	Value	Grade
Water Clarity (Secchi Depth)	2.2 m	C
Phosphorus	13 µg/L	A
Chlorophyll-a (Algae)	6.2 µg/L	B
Trophic State Index (TSI)	46	Mesotrophic

Moderate nutrients, good water quality

Where to stay near Lac de la Grande Fourche

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