What is the cleanest lake in O'Brien County, Iowa?

Dog Creek Lake in O'Brien County is the highest-rated lake in O'Brien County, Iowa with an EPA water quality grade of D and 3.4 feet of water clarity.

How are these rankings calculated?

Lakes are graded A through F on nutrients and algae — total phosphorus, nitrogen, chlorophyll-a, and turbidity — against EPA National Lakes Assessment 2022 condition classes for that lake’s ecoregion. Water clarity (Secchi depth) is measured and shown; it is not the letter. Lakes without enough recent samples are UNRATED, not given an F. Source data comes from the EPA Water Quality Portal.

Cleanest Lakes in O'Brien County, Iowa

Dog Creek Lake in O'Brien County leads the rankings with a water quality grade of D and 3.4 ft of clarity. Below are the top 2 cleanest monitored lakes in O'Brien County, Iowa, ranked by EPA water quality score.

Ranked List

#	Lake	County	Grade	Clarity	Phosphorus	Algae
1	Dog Creek Lake	O'Brien	D	3.4 ft	58 µg/L	25 µg/L
2	Mill Creek Lake	O'Brien	D	3 ft	62 µg/L	28.4 µg/L

Ranked List

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