Eutrophic Lakes in Ohio

15 eutrophic lakes in Ohio. High nutrients, frequent algae, reduced clarity.

Eutrophic lakes — TSI 50 to 70 — are nutrient-rich and productive, with persistent summer algal communities that drive visible reductions in clarity. These conditions are not failures; they reflect a lake doing what nutrient-loaded waters do. 15 Ohio lakes register as eutrophic. Only 0% are deep — eutrophy correlates with shallowness, agricultural watersheds, and the kind of nutrient-input history that takes decades to shift.

Eutrophic lakes typically grade C or D on the LakeGrade rubric. The same nutrient richness that defines the trophic class drives the lower grade.

#	Lake	County	Grade	Clarity	Depth	TSI
1	Caesar Creek Lake	Warren	C	3.8 ft	-	55
2	Caesar Creek Lake	Warren	C	3.5 ft	-	56
3	Caesar Creek Lake	Warren	D	3.2 ft	-	57
4	Caesar Creek Lake	Warren	D	3 ft	-	58
5	Leesville Lake	Carroll	D	5 ft	-	54
6	Sites Lake	Richland	D	5.2 ft	-	53
7	Tappan Lake	Harrison	D	-	-	67
8	Buck Creek Lake	Clark	D	2.5 ft	-	63
9	Buck Creek Lake	Clark	D	2.3 ft	-	63
10	Buck Creek Lake	Clark	D	2.1 ft	-	64
11	Buck Creek Lake	Clark	D	2.5 ft	-	63
12	Seneca Lake	Noble	F	1.7 ft	-	70
13	Tappan Lake	Harrison	F	1.8 ft	-	68
14	Clear Fork Reservoir	Morrow	F	3.1 ft	-	61
15	Pleasant Hill Reservoir	Richland	F	3 ft	-	61

All eutrophic lakes →Minnesota version →Wisconsin version →Illinois version →Michigan version →Iowa version →Pennsylvania version →New York version →Missouri version →Indiana version →North Dakota version →South Dakota version →All Ohio lakes →

Source: EPA National Aquatic Resource Surveys, 2026.