Is Lac Saint-Jean safe to swim in?

Good for swimming, clear water with low algae levels. Lac Saint-Jean has an overall water quality grade of B. Algae concentration (chlorophyll-a) is 2 µg/L. Always check local health department advisories before swimming.

Le Domaine-du-Roy County, Québec · Water Quality Report Card

Lac Saint-Jean

Grade B — Good

Mesotrophic

Lac Saint-Jean in Le Domaine-du-Roy, Québec received a water quality grade of B (Good). Water clarity: 2 m visibility. Phosphorus: 7.5 µg/L. Chlorophyll-a (algae): 2 µg/L.

Clarity: 2 m
Type: Mesotrophic

Where to stay →Safe to swim?

Lac Saint-Jean is a mesotrophic lake in Le Domaine-du-Roy County, Québec. Water quality is graded B based on 3 sampling years through 2025. Compared to the 12 other monitored lakes in Le Domaine-du-Roy County, Lac Saint-Jean ranks #12 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

Murky, only visible to about 6.6 ft. Phosphorus level: 7.5 µg/L. Chlorophyll-a: 2 µg/L. Trophic State Index: 40.

Metric	Value	Grade
Water Clarity (Secchi Depth)	2 m	D
Phosphorus	7.5 µg/L	A
Chlorophyll-a (Algae)	2 µg/L	A
Trophic State Index (TSI)	40	Mesotrophic

Moderate nutrients, good water quality

Where to stay near Lac Saint-Jean

Compare lakeside cabins, hotels, and vacation rentals near Lac Saint-Jean in Le Domaine-du-Roy, Québec — live availability and prices for your trip. Switch the map to Satellite to see the lake and how close each stay is to the water.

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Fishing Lac Saint-Jean

→ Lac Saint-Jean fishing regulations (limits, seasons, special rules)

Location

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County Ranking

Ranked #12 of 13 lakes in Le Domaine-du-Roy

Cleaner Lakes Within 30 Miles

Lac Saint-Jean holds Grade B. 4 nearby lakes hold higher grades.

See full comparison →

Nearby Lakes in Le Domaine-du-Roy

Explore Lac Saint-Jean across LakeGrade

Lake Fishing Forecast

Species activity outlook by water temperature and season

Mesotrophic Lakes

Moderate nutrients, good water quality

The State of Québec's Lakes

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Cleanest lakes in Québec

Top 25 by overall water quality score

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Top 25 by Secchi water clarity

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Grade A/B + low algae filter

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Panfish-rich, public access

All Québec lakes

Full state directory

Other Grade B Lakes in Québec

Lac à Houde

Maria-Chapdelaine · 1.5 m

Lac Brochet

Maria-Chapdelaine · 2.4 m

Lac Noir

Maria-Chapdelaine · 2 m

Lac Trottier

Maria-Chapdelaine · 2.7 m

Lac Noir

Lac-Saint-Jean-Est · 1.5 m

Grand Lac Sec

Lac-Saint-Jean-Est · 2.7 m

Mesotrophic Lakes in Québec

Lac Brochet Lac Noir Lac Trottier Lac Noir

More records, surveys & data sources

Where this data comes from

Measurements for Lac Saint-Jean 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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