Lakes with Declining Water Quality

1,068 lakes across Minnesota and Wisconsin 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	Mud Lake	Hennepin	MN	F	↓ Declining	2
2	Pike Lake	Scott	MN	F	↓ Declining	4
3	Tetonka Lake	Le Sueur	MN	F	↓ Declining	5
4	Clear Lake	Meeker	MN	F	↓ Declining	5
5	Eagle Lake	Carver	MN	F	↓ Declining	5
6	Fish Lake	Kanabec	MN	F	↓ Declining	5
7	Sand Lake	Stearns	MN	F	↓ Declining	4
8	Hook Lake	McLeod	MN	F	↓ Declining	4
9	Roberds Lake	Rice	MN	F	↓ Declining	5
10	Cedar Lake	Scott	MN	F	↓ Declining	3
11	Rice Lake	Anoka	MN	F	↓ Declining	4
12	Rhine Lake	Pine	MN	F	↓ Declining	5
13	Silver Lake	Mille Lacs	MN	F	↓ Declining	2
14	Goose Lake	Ramsey	MN	F	↓ Declining	5
15	Goose Lake	Hennepin	MN	F	↓ Declining	2
16	Hall Lake	Martin	MN	F	↓ Declining	5
17	Fountain Lake	Wright	MN	F	↓ Declining	5
18	Fountain Lake	Freeborn	MN	F	↓ Declining	5
19	Crystal Lake	Blue Earth	MN	F	↓ Declining	4
20	Diamond Lake	Hennepin	MN	F	↓ Declining	4
21	Mink Lake	Wright	MN	F	↓ Declining	5
22	Stowe Lake	Douglas	MN	F	↓ Declining	2
23	Rush Lake	Sherburne	MN	F	↓ Declining	5
24	Vadnais Lake	Ramsey	MN	F	↓ Declining	5
25	Whiteface Reservoir	St. Louis	MN	F	↓ Declining	5
26	Circle Lake	Rice	MN	F	↓ Declining	5
27	Hanska Lake	Brown	MN	F	↓ Declining	4
28	Blueberry Lake	St. Louis	MN	F	↓ Declining	4
29	Cleary Lake	Scott	MN	F	↓ Declining	4
30	Loon Lake	Blue Earth	MN	F	↓ Declining	3
31	Loon Lake	Waseca	MN	F	↓ Declining	2
32	Kohlman Lake	Ramsey	MN	F	↓ Declining	5
33	Lost Lake	Hennepin	MN	F	↓ Declining	5
34	Johnson Lake	St. Louis	MN	F	↓ Declining	2
35	Swede Lake	Carver	MN	F	↓ Declining	5
36	Staring Lake	Hennepin	MN	F	↓ Declining	3
37	Simon Lake	Pope	MN	F	↓ Declining	5
38	Hope Lake	Meeker	MN	F	↓ Declining	3
39	Rice Lake	Hennepin	MN	F	↓ Declining	2
40	Unn Pond	Dakota	MN	F	↓ Declining	5
41	Grass Lake	Hennepin	MN	F	↓ Declining	2
42	Mccarthy Lake	Dakota	MN	F	↓ Declining	5
43	Center Lakelanding	Cook	MN	F	↓ Declining	4
44	Helmer_nelson Pond Middle	Cook	MN	F	↓ Declining	4
45	Helmer_nelson Pond Inlet	Cook	MN	F	↓ Declining	4
46	Helmer_nelson Pond East End Beaver House	Cook	MN	F	↓ Declining	4
47	Pickeral Lake	Freeborn	MN	F	↓ Declining	2
48	Little Waverly Lake	Wright	MN	F	↓ Declining	5
49	Quigley Lake	Dakota	MN	F	↓ Declining	5
50	Watkins Lake	Waseca	MN	F	↓ Declining	2

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