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LakeQuality

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. 9 hypereutrophic lakes are on the Massachusetts 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
1Nashawannuck PondHampshireF--65
2Bartlett PondWorcesterF--66
3Gleasons PondMiddlesexF--68
4Barkers PondMiddlesexF--70
5Furnace PondPlymouthF--68
6Mill PondBarnstableF--64
7Cooks PondPlymouthF--69
8South Watuppa PondBristolF--68
9Wedge PondMiddlesexF--72

Source: EPA National Aquatic Resource Surveys, 2026.