Lakes with Declining Water Quality

1,349 lakes across our 12-state dataset show declining water quality trends. These lakes have gotten worse based on multi-year monitoring of clarity, phosphorus, and algae levels.

Rank	Lake	County	State	Grade	Trend	Years Monitored
1	Long Lake	Stearns	MN	F	↓ Declining	6
2	Clear Lake	Meeker	MN	F	↓ Declining	6
3	Clear Lake	Waseca	MN	F	↓ Declining	5
4	Eagle Lake	Carver	MN	F	↓ Declining	6
5	Fish Lake	Kanabec	MN	F	↓ Declining	6
6	Hook Lake	McLeod	MN	F	↓ Declining	6
7	Grace Lake	Carver	MN	F	↓ Declining	6
8	Rhine Lake	Pine	MN	F	↓ Declining	6
9	Mud Lake	Hennepin	MN	F	↓ Declining	2
10	Sand Lake	Stearns	MN	F	↓ Declining	4
11	Union Lake	Rice	MN	F	↓ Declining	3
12	Sandy Lake	Anoka	MN	F	↓ Declining	5
13	Goose Lake	Hennepin	MN	F	↓ Declining	2
14	Silver Lake	Mille Lacs	MN	F	↓ Declining	3
15	Crystal Lake	Blue Earth	MN	F	↓ Declining	4
16	Knife Lake	Kanabec	MN	F	↓ Declining	6
17	Mink Lake	Wright	MN	F	↓ Declining	6
18	Rush Lake	Sherburne	MN	F	↓ Declining	5
19	Schultz Lake	Kandiyohi	MN	F	↓ Declining	6
20	Vadnais Lake	Ramsey	MN	F	↓ Declining	6
21	Whiteface Reservoir	St. Louis	MN	F	↓ Declining	6
22	Sarah Lake	Hennepin	MN	F	↓ Declining	6
23	Little Rock Lake	Benton	MN	F	↓ Declining	6
24	Circle Lake	Rice	MN	F	↓ Declining	6
25	Wallmark Lake	Chisago	MN	F	↓ Declining	6
26	Hanska Lake	Brown	MN	F	↓ Declining	4
27	Cleary Lake	Scott	MN	F	↓ Declining	5
28	Loon Lake	Blue Earth	MN	F	↓ Declining	3
29	Loon Lake	Waseca	MN	F	↓ Declining	3
30	Mazaska Lake	Rice	MN	F	↓ Declining	6
31	Swede Lake	Carver	MN	F	↓ Declining	6
32	Hope Lake	Meeker	MN	F	↓ Declining	3
33	Rice Lake	Hennepin	MN	F	↓ Declining	2
34	Unn Lake	Hennepin	MN	F	↓ Declining	5
35	Unn Pond	Dakota	MN	F	↓ Declining	6
36	Mccarthy Lake	Dakota	MN	F	↓ Declining	6
37	Silver Lake	Ramsey	MN	F	↓ Declining	6
38	Center Lakelanding	Cook	MN	F	↓ Declining	5
39	Helmer_nelson Pond Middle	Cook	MN	F	↓ Declining	5
40	Dutchman Lakelanding	Cook	MN	F	↓ Declining	5
41	Helmer_nelson Pond Inlet	Cook	MN	F	↓ Declining	5
42	Helmer_nelson Pond East End Beaver House	Cook	MN	F	↓ Declining	5
43	Pickeral Lake	Freeborn	MN	F	↓ Declining	3
44	Quigley Lake	Dakota	MN	F	↓ Declining	6
45	Watkins Lake	Waseca	MN	F	↓ Declining	2
46	Florida Slough Lake	Kandiyohi	MN	F	↓ Declining	6
47	School Grove Lake	Lyon	MN	F	↓ Declining	4
48	Little Waverly Lake	Wright	MN	F	↓ Declining	6
49	Little Lake Inlet	Cook	MN	F	↓ Declining	5
50	Byllesby Lake	Dakota	MN	F	↓ Declining	3

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