Question 1

Cleanest Lakes in Marshall County, Iowa?

Accepted Answer

Sand Lake in Marshall County leads the rankings on measured clarity and nutrients and 6.4 ft of clarity. Below are the top 3 cleanest monitored lakes in Marshall County, Iowa, ranked on EPA nutrient and algae measurements.

Question 2

What is the cleanest lake in Marshall County, Iowa?

Accepted Answer

Sand Lake in Marshall County has the cleanest nutrient and algae readings in Marshall County, Iowa, with 6.4 feet of measured water clarity.

Question 3

How are these rankings calculated?

Accepted Answer

Nutrients and algae, total phosphorus, nitrogen, chlorophyll-a and turbidity, are read against EPA National Lakes Assessment 2022 condition classes for that lake’s ecoregion. Water clarity (Secchi depth) is measured and shown separately. Lakes without enough recent samples are listed without a condition class rather than ranked low. Source data comes from the EPA Water Quality Portal.

#	Lake	County	Clarity	Phosphorus	Algae
1	Sand Lake	Marshall	6.4 ft	25 µg/L	3.6 µg/L
2	Green Castle Lake	Marshall	4.6 ft	59 µg/L	6.9 µg/L
3	Crab Tree Lake	Marshall	-	-	-

Cleanest Lakes in Marshall County, Iowa

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