Hypereutrophic Lakes in North Dakota

11 hypereutrophic lakes in North Dakota. 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. 11 hypereutrophic lakes are on the North Dakota 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.

#	Lake	County	Grade	Clarity	Depth	TSI
1	Dry Lake	Ramsey	D	2.8 ft	-	72
2	Sweetwater Lake	Ramsey	D	2.9 ft	-	71
3	Morrison Lake	Ramsey	F	1.9 ft	-	79
4	Mchugh Slough Lake	Nelson	F	1.6 ft	-	78
5	Buffalo Lake	Pierce	F	0.3 ft	-	88
6	Juanita Lake	Foster	F	1 ft	-	79
7	Kalmbach Lake	LaMoure	F	0.7 ft	-	78
8	Gordon Beach Lake	Rolette	F	1 ft	-	77
9	Belcourt Lake Beach	Rolette	F	1 ft	-	77
10	Cedar Lake	Slope	F	1.3 ft	-	71
11	Niagara Dam Lake	Grand Forks	F	1 ft	-	77

All hypereutrophic lakes →Minnesota version →Wisconsin version →Illinois version →Michigan version →Iowa version →Ohio version →Pennsylvania version →New York version →Missouri version →Indiana version →South Dakota version →All North Dakota lakes →

Source: EPA National Aquatic Resource Surveys, 2026.