Most Polluted Lakes: Worst Water Quality

The 50 lakes with the lowest water quality grades. These lakes have high phosphorus, excessive algae, or very low visibility. Swimming is generally not recommended.

Rank	Lake	County	State	Grade	Clarity	Phosphorus	Algae
1	Kabetogama Lake	St. Louis	MN	F	2.6 ft	-	-
2	North Long Lake	Ramsey	MN	F	2.5 ft	102 µg/L	-
3	Snelling Lake	Hennepin	MN	F	1.8 ft	99 µg/L	53.5 µg/L
4	Horseshoe Lake	Rice	MN	F	2 ft	-	-
5	Long Lake	Stearns	MN	F	2.5 ft	324.5 µg/L	-
6	Long Lake	Cottonwood	MN	F	1 ft	-	-
7	Long Lake	Hennepin	MN	F	3.3 ft	90 µg/L	-
8	Long Lake	Dakota	MN	F	1.6 ft	110 µg/L	82 µg/L
9	Jonathan Lake	Carver	MN	F	1.5 ft	157.5 µg/L	-
10	Peltier Lake	Anoka	MN	F	2.5 ft	374 µg/L	-
11	Clear Lake	Meeker	MN	F	3 ft	140 µg/L	-
12	Clear Lake	Brown	MN	F	0.8 ft	196 µg/L	-
13	Clear Lake	Waseca	MN	F	2.5 ft	151 µg/L	-
14	Clear Lake	Stevens	MN	F	0.7 ft	288 µg/L	-
15	Clear Lake	Le Sueur	MN	F	1.2 ft	309.5 µg/L	-
16	Eagle Lake	Carver	MN	F	2 ft	169 µg/L	-
17	Eagle Lake	Blue Earth	MN	F	1 ft	-	-
18	Fish Lake	Kanabec	MN	F	2 ft	-	-
19	Fish Lake	Becker	MN	F	1 ft	136 µg/L	-
20	Hook Lake	McLeod	MN	F	2.5 ft	-	-
21	Allie Lake	Renville	MN	F	3 ft	214 µg/L	-
22	Roberds Lake	Rice	MN	F	2.5 ft	355 µg/L	-
23	Grace Lake	Carver	MN	F	2.6 ft	91.5 µg/L	-
24	Charlotte Lake	Stevens	MN	F	0.9 ft	237 µg/L	-
25	Cedar Lake	Scott	MN	F	2 ft	97.5 µg/L	58 µg/L
26	Wing Lake	Hennepin	MN	F	2.1 ft	120 µg/L	-
27	Rhine Lake	Pine	MN	F	2.5 ft	-	-
28	Lawrence Lake	Houston	MN	F	2.3 ft	-	-
29	Mud Lake	Hennepin	MN	F	0.9 ft	150 µg/L	-
30	Mud Lake	Otter Tail	MN	F	1.6 ft	-	-
31	Mud Lake	Stearns	MN	F	3 ft	166 µg/L	-
32	Mud Lake	Martin	MN	F	1.6 ft	125.5 µg/L	53.4 µg/L
33	Pike Lake	Scott	MN	F	2.3 ft	189.4 µg/L	-
34	Pike Lake	Ramsey	MN	F	2.3 ft	124 µg/L	-
35	Unnamed Lake	Meeker	MN	F	0.7 ft	224 µg/L	-
36	Unnamed Lake	Benton	MN	F	1.5 ft	-	-
37	Unnamed Lake	Becker	MN	F	1.2 ft	-	-
38	Unnamed Lake	Swift	MN	F	0.7 ft	224 µg/L	-
39	Unnamed Lake	Watonwan	MN	F	1 ft	275 µg/L	-
40	Unnamed Lake	Douglas	MN	F	3.3 ft	-	-
41	Unnamed Lake	Otter Tail	MN	F	1.3 ft	-	-
42	Unnamed Lake	Big Stone	MN	F	2 ft	518.5 µg/L	-
43	Unnamed Lake	Wright	MN	F	1.6 ft	-	-
44	Unnamed Lake	Pope	MN	F	3 ft	-	-
45	Unnamed Lake	Itasca	MN	F	3.3 ft	-	-
46	Unnamed Lake	Stevens	MN	F	1.1 ft	-	-
47	Unnamed Lake	Grant	MN	F	0.7 ft	269 µg/L	-
48	Unnamed Lake	Brown	MN	F	0.3 ft	1300 µg/L	-
49	Unnamed Lake	Hennepin	MN	F	-	220.5 µg/L	-
50	Tetonka Lake	Le Sueur	MN	F	3 ft	282 µg/L	-

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