Question 1

Cleanest Lakes in Polk County, Minnesota?

Accepted Answer

Union Lake in Polk County leads the rankings with a water quality grade of A and 14.5 ft of clarity. Below are the top 20 cleanest monitored lakes in Polk County, Minnesota, ranked by EPA water quality score.

Question 2

What is the cleanest lake in Polk County, Minnesota?

Accepted Answer

Union Lake in Polk County is the highest-rated lake in Polk County, Minnesota with an EPA water quality grade of A and 14.5 feet of water clarity.

Question 3

How are these rankings calculated?

Accepted Answer

Lakes are graded A through F using the Metropolitan Council methodology, which combines Secchi depth (water clarity), total phosphorus, and chlorophyll-a (algae) into a single score. Source data comes from the EPA Water Quality Portal.

#	Lake	County	Grade	Clarity	Phosphorus	Algae
1	Union Lake	Polk	A	14.5 ft	14 µg/L	-
2	Cable Lake	Polk	B	10.2 ft	20 µg/L	-
3	Sand Hill Lake	Polk	B	6.9 ft	26 µg/L	-
4	Poplar Lake	Polk	B	8.9 ft	23 µg/L	-
5	Badger Lake	Polk	B	6.7 ft	27 µg/L	-
6	Sarah Lake	Polk	B	7.9 ft	29.5 µg/L	-
7	Kittleson Lake	Polk	B	7.1 ft	26 µg/L	-
8	Spring Lake	Polk	C	4.9 ft	27.5 µg/L	-
9	Whitefish Lake	Polk	C	4.1 ft	42.5 µg/L	-
10	Maple Lake	Polk	C	3.4 ft	38 µg/L	-
11	Turtle Lake	Polk	C	3.6 ft	56.5 µg/L	-
12	Uff Lake	Polk	C	3.9 ft	35 µg/L	-
13	Unnamed Lake	Polk	D	2.6 ft	52 µg/L	-
14	Unnamed Lake	Polk	D	6.9 ft	95 µg/L	-
15	Cross Lake	Polk	D	3 ft	57 µg/L	-
16	Store Lake	Polk	D	6.9 ft	193 µg/L	-
17	Halverson Lake	Polk	D	3 ft	51 µg/L	-
18	Hill River Lake	Polk	D	4.6 ft	95 µg/L	-
19	Oak Lake	Polk	F	3 ft	144 µg/L	-
20	Cameron Lake	Polk	F	1 ft	133 µg/L	-

Cleanest Lakes in Polk County, Minnesota

Ranked List

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