What is the cleanest lake in Morton County, North Dakota?

Nygren Dam Lake in Morton County is the highest-rated lake in Morton County, North Dakota with an EPA water quality grade of D and 2.6 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 Morton County, North Dakota

Nygren Dam Lake in Morton County leads the rankings with a water quality grade of D and 2.6 ft of clarity. Below are the top 5 cleanest monitored lakes in Morton County, North Dakota, ranked by EPA water quality score.

Ranked List

#	Lake	County	Grade	Clarity	Phosphorus	Algae
1	Nygren Dam Lake	Morton	D	2.6 ft	73 µg/L	24.7 µg/L
2	Sweetbriar Dam Lake	Morton	F	3 ft	353 µg/L	54 µg/L
3	Fish Creek Lake	Morton	NR	-	-	-
4	Storm Creek Lake	Morton	NR	-	-	-
5	Crown Butte Lake	Morton	NR	-	-	-

Ranked List

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