Mesotrophic Lakes in Iowa

14 mesotrophic lakes in Iowa. Moderate nutrients, good water quality.

Most well-managed working lakes register as mesotrophic — the band that balances productivity with clarity. 14 lakes in Iowa sit in the mesotrophic band. About 0% are deep (50+ ft); the rest are shallower basins where watershed management keeps nutrients from pushing the system into eutrophy.

Mesotrophic lakes tend to grade B or C on the LakeGrade rubric — the productive-but-clear band lines up with the middle of the letter grades.

#	Lake	County	Grade	Clarity	Depth	TSI
1	West Okoboji Lake	Dickinson	A	15.7 ft	-	41
2	Dale Maffitt Reservoir	Dallas	A	9.8 ft	-	43
3	Blue Pit Lake	Cerro Gordo	A	17.1 ft	-	41
4	Ada Hayden Heritage Park Lake	Story	A	6.8 ft	-	48
5	Nine Eagles Lake	Decatur	A	11 ft	-	43
6	Little Sioux Park Lake	Woodbury	A	5.7 ft	-	49
7	Rudd Lake	Floyd	A	8.1 ft	-	45
8	Slipbluff Lake	Decatur	A	9 ft	-	45
9	Lacey Keosauqua Lake	Van Buren	A	7.1 ft	-	48
10	Yenruogis Pond	Keokuk	A	9.9 ft	-	47
11	Sand Lake	Marshall	A	6.4 ft	-	48
12	Terra Park Lake	Polk	A	11.5 ft	-	45
13	Green Castle Lake	Marshall	C	4.6 ft	-	56
14	Lambach Lake	Scott	C	7.9 ft	-	53

All mesotrophic lakes →Minnesota version →Wisconsin version →Illinois version →Michigan version →Ohio version →Pennsylvania version →New York version →Missouri version →Indiana version →North Dakota version →South Dakota version →Florida version →Colorado version →North Carolina version →Vermont version →Texas version →Oregon version →Arkansas version →Oklahoma version →Kansas version →Nebraska version →Nevada version →Arizona version →Idaho version →Montana version →New Mexico version →Tennessee version →Alabama version →Virginia version →Kentucky version →Utah version →Washington version →Wyoming version →Georgia version →Massachusetts version →Ontario version →Québec version →All Iowa lakes →

Source: EPA National Aquatic Resource Surveys, 2026.