Lakes in Mercer County, Ohio
1 lakes counted in Mercer County - the largest is Grand Lake St. Marys at 13,356 acres.
1
Lakes Counted
13,356 acres
Largest - Grand Lake St. Marys
14 ft
Deepest - Grand Lake St. Marys
Mercer County, highlighted, with its largest counted lakes dotted. Outlines from Census boundary data.
All Counted Lakes
| # | Lake | County | Surface Area | Max Depth |
|---|---|---|---|---|
| 1 | Grand Lake St. Marys | Mercer | 13,356 acres | 14 ft |
Sources: Ohio DNR lake data; USGS. Verified October 28, 2026.