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LakeQuality

Hypereutrophic Lakes in Québec

3 hypereutrophic lakes in Québec. Very high nutrients, dense algae, poor clarity.

Hypereutrophic lakes (TSI above 70) are at the upper end of the productivity scale: visible algal blooms most weeks of summer, clarity often under 3 feet, and meaningful risk of harmful-algal-bloom toxin events. 3 hypereutrophic lakes are on the Québec books. Almost none of them are deep — 0% break 50 feet. Shallow basin plus heavy nutrient input is the consistent recipe.

Hypereutrophic lakes overwhelmingly grade D or F — the trophic class and the grade are measuring closely-related dimensions of the same underlying nutrient regime.

#LakeCountyGradeClarityDepthTSI
1Lac Saint-CharlesBellechasseF1 ft-73
2Petit Lac Saint-FrançOisLe Val-Saint-FrançoisF2.3 ft-72
3Lac BleuRouvilleF1.1 ft-76

Source: EPA National Aquatic Resource Surveys, 2026.