What is the cleanest lake in Benton County, Iowa?

Hannen Lake in Benton County is the highest-rated lake in Benton County, Iowa with an EPA water quality grade of F and 1.2 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 Benton County, Iowa

Hannen Lake in Benton County leads the rankings with a water quality grade of F and 1.2 ft of clarity. Below are the top 2 cleanest monitored lakes in Benton County, Iowa, ranked by EPA water quality score.

Ranked List

#	Lake	County	Grade	Clarity	Phosphorus	Algae
1	Hannen Lake	Benton	F	1.2 ft	141 µg/L	119.9 µg/L
2	Rodgers Lake	Benton	F	2.6 ft	91.5 µg/L	44.5 µg/L

Ranked List

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