Hypereutrophic

Hypereutrophic Lakes in Minnesota & Wisconsin

Very high nutrients, dense algae, poor clarity. 178 lakes (5% of all graded lakes).

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. 178 hypereutrophic lakes are on the Minnesota and Wisconsin books. Almost none of them are deep — 4% 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.

Oligotrophic Mesotrophic Eutrophic Hypereutrophic

Lake	County	State	Grade	Clarity	Depth
Ann Lake	Pope	MN	D	8.4 ft	14 ft
Mud Lake	Otter Tail	MN	D	1.3 ft	-
Unnamed Lake	Wright	MN	D	1.3 ft	38 ft
Star Lake	Meeker	MN	D	1 ft	15 ft
Ann Lake	Wright	MN	D	3.7 ft	18.5 ft
Swartout Lake	Wright	MN	D	5.2 ft	-
Winsted Lake	McLeod	MN	D	3.3 ft	12 ft
Porter Lake	Blue Earth	MN	D	1.3 ft	-
Indian Lake	Dane	WI	D	3.9 ft	-
Dexter Lake	Wood	WI	D	4.9 ft	17 ft
Mud Lake	Hennepin	MN	F	0.9 ft	-
Mud Lake	Hennepin	MN	F	3 ft	-
Pike Lake	Scott	MN	F	2 ft	9 ft
Long Lake	Cottonwood	MN	F	1 ft	-
Unnamed Lake	Ramsey	MN	F	1 ft	-
Unnamed Lake	Meeker	MN	F	0.7 ft	15 ft
Unnamed Lake	Benton	MN	F	1.5 ft	-
Unnamed Lake	Becker	MN	F	1.2 ft	-
Unnamed Lake	Otter Tail	MN	F	1.3 ft	-
Unnamed Lake	Big Stone	MN	F	2 ft	15 ft
Unnamed Lake	Stevens	MN	F	1.1 ft	-
Unnamed Lake	Swift	MN	F	0.7 ft	-
Unnamed Lake	Watonwan	MN	F	1 ft	-
Unnamed Lake	Grant	MN	F	0.7 ft	-
Unnamed Lake	Hennepin	MN	F	-	-
Jonathan Lake	Carver	MN	F	1.5 ft	-
Peltier Lake	Anoka	MN	F	2 ft	18 ft
Tetonka Lake	Le Sueur	MN	F	3 ft	35 ft
Wakanda Lake	Kandiyohi	MN	F	0.5 ft	-
Saint Johns Lake	Kandiyohi	MN	F	0.5 ft	-
Clear Lake	Brown	MN	F	0.8 ft	8 ft
Clear Lake	Waseca	MN	F	2.5 ft	34 ft
Clear Lake	Stevens	MN	F	0.7 ft	-
Eagle Lake	Carver	MN	F	2.3 ft	14 ft
Eagle Lake	Blue Earth	MN	F	1 ft	9 ft
Fish Lake	Becker	MN	F	1 ft	-
Wheeler North Lake	Kandiyohi	MN	F	1 ft	-
Allie Lake	Renville	MN	F	2 ft	12 ft
Roberds Lake	Rice	MN	F	2 ft	43 ft
Charlotte Lake	Stevens	MN	F	0.9 ft	20 ft
Island Lake	Lyon	MN	F	2 ft	8 ft
Rice Lake	Hennepin	MN	F	2 ft	11.5 ft
Pokegama Lake	Pine	MN	F	2 ft	25 ft
George Lake	Martin	MN	F	1.6 ft	11 ft
Ox Yoke Lake	Hennepin	MN	F	2.6 ft	-
Silver Lake	Mille Lacs	MN	F	1 ft	-
Big Woods Lake	Carver	MN	F	1 ft	-
Goose Lake	Ramsey	MN	F	0.7 ft	6 ft
Goose Lake	Carver	MN	F	1 ft	10 ft
Goose Lake	Hennepin	MN	F	0.8 ft	8 ft
Typo Lake	Anoka	MN	F	1 ft	6 ft
Powderhorn Lake	Hennepin	MN	F	1.3 ft	24 ft
Fountain Lake	Wright	MN	F	1 ft	10 ft
Fountain Lake	Freeborn	MN	F	1.5 ft	14 ft
Crystal Lake	Blue Earth	MN	F	1.5 ft	8 ft
Benton Lake	Carver	MN	F	0.8 ft	-
Foster Lake	Wright	MN	F	1.6 ft	10 ft
Knife Lake	Kanabec	MN	F	2.3 ft	15 ft
Diamond Lake	Hennepin	MN	F	1.4 ft	8 ft
Ardmore Lake	Hennepin	MN	F	1.6 ft	20 ft
Uhl Lake	Wright	MN	F	1 ft	-
Schultz Lake	Kandiyohi	MN	F	1.6 ft	-
Alice Lake	Otter Tail	MN	F	0.5 ft	-
Cornelia Lake	Hennepin	MN	F	0.8 ft	6.5 ft
Wood Lake	Yellow Medicine	MN	F	3 ft	9 ft
Arvilla Lake	Meeker	MN	F	1 ft	9 ft
Vadnais Lake	Ramsey	MN	F	1 ft	9 ft
Langdon Lake	Hennepin	MN	F	1.5 ft	38 ft
Circle Lake	Rice	MN	F	1.5 ft	14 ft
Little Rock Lake	Benton	MN	F	2 ft	17 ft
Hanska Lake	Brown	MN	F	1 ft	16 ft
Cleary Lake	Scott	MN	F	2.3 ft	9 ft
Hazeltine Lake	Carver	MN	F	1 ft	-
Loon Lake	Jackson	MN	F	0.9 ft	8 ft
Loon Lake	Waseca	MN	F	2 ft	9 ft
Sylvan Lake	Hennepin	MN	F	1.1 ft	-
Cameron Lake	Polk	MN	F	1 ft	9 ft
Miller Lake	Carver	MN	F	1.6 ft	14 ft
Mcknight Lake	Carver	MN	F	2.3 ft	-
Lost Lake	Hennepin	MN	F	1.5 ft	6 ft
Parley Lake	Carver	MN	F	1.6 ft	18 ft
Wheeler South Lake	Kandiyohi	MN	F	2 ft	-
Chub Lake	Dakota	MN	F	0.5 ft	10 ft
Amber Lake	Martin	MN	F	2 ft	19 ft
Swede Lake	Carver	MN	F	2.3 ft	12 ft
Augusta Lake	Dakota	MN	F	-	-
Muewissen Lake	Carver	MN	F	1.6 ft	-
Malmedal Lake	Pope	MN	F	1 ft	10 ft
Indianhead Lake	Hennepin	MN	F	1.6 ft	-
Simon Lake	Pope	MN	F	1.3 ft	-
Edina Lake	Hennepin	MN	F	0.8 ft	-
Dean Lake	Wright	MN	F	2.6 ft	20 ft
Lower Orono Lake	Sherburne	MN	F	2.3 ft	18 ft
Hope Lake	Meeker	MN	F	2 ft	10 ft
Unn Lake	Hennepin	MN	F	2.5 ft	-
Unn Pond	Dakota	MN	F	2 ft	-
Grass Lake	Hennepin	MN	F	-	-
Uhlenkolts Lake	Stearns	MN	F	0.7 ft	18 ft
Cottonwood Lake	Lyon	MN	F	1.8 ft	7 ft
Wells Lake	Rice	MN	F	1.5 ft	4 ft

Showing 100 of 178 hypereutrophic lakes.

Frequently Asked Questions

What is an hypereutrophic lake?

Very high nutrients, dense algae, poor clarity. There are 178 hypereutrophic lakes in Minnesota and Wisconsin, representing 5% of all graded lakes.

Can you swim in hypereutrophic lakes?

Hypereutrophic lakes are generally not safe for swimming due to dense algae, potential toxins, and very poor visibility.

Source: EPA National Aquatic Resource Surveys, 2026.