What is the cleanest lake in Polk County, Iowa?

Terra Park Lake in Polk County has the cleanest nutrient and algae readings in Polk County, Iowa, with 11.5 feet of measured water clarity.

How are these rankings calculated?

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.

Cleanest Lakes in Polk County, Iowa

Terra Park Lake in Polk County leads the rankings on measured clarity and nutrients and 11.5 ft of clarity. Below are the top 10 cleanest monitored lakes in Polk County, Iowa, ranked on EPA nutrient and algae measurements.

Ranked List

#	Lake	County	Clarity	Phosphorus	Algae
1	Terra Park Lake	Polk	11.5 ft	20 µg/L	4.7 µg/L
2	Lake Petocka	Polk	3.3 ft	39.5 µg/L	9.3 µg/L
3	Thomas Mitchell Lake	Polk	3.3 ft	87 µg/L	13.2 µg/L
4	Easter Lake	Polk	2.9 ft	49.5 µg/L	22.8 µg/L
5	Big Creek Lake	Polk	2.6 ft	80 µg/L	35.7 µg/L
6	Grays Lake	Polk	1.6 ft	103 µg/L	46.5 µg/L
7	Blue Heron Lake	Polk	2.2 ft	78.5 µg/L	57.9 µg/L
8	Fort des Moines Park Pond	Polk	2.8 ft	68 µg/L	32.6 µg/L
9	Brenton Slough	Polk	-	-	-
10	Saylorville Lake	Polk	-	-	-

Ranked List

More Answers for Polk County, Iowa