Map of All 1,402 Ohio Dams
Ohio has 1,402 dams in the National Inventory of Dams — and 421 are classified as high hazard (30% of the state’s total), meaning failure would likely cause loss of life. 132 Ohio dams are both high-hazard and in poor or unsatisfactory condition.
Use the interactive Ohio dams map below to explore every dam in the state, color-coded by hazard level. Click any dam for its condition assessment, last inspection date, and Emergency Action Plan status. Or view the full US Dams interactive map to compare Ohio to every other state.
Hazard
Condition
Purpose
Ohio Dams by the Numbers
- 1,402 total dams in Ohio
- 421 high hazard — failure would likely cause loss of life
- 564 significant hazard
- 340 low hazard
- 509 in poor or unsatisfactory condition (501 poor, 8 unsatisfactory)
- 132 Ohio dams are both high-hazard AND in poor/unsatisfactory condition
Data source: US Army Corps of Engineers, National Inventory of Dams (NID).
The Tallest Dams in Ohio
The tallest dam in Ohio is No. 2 Slurry Pond at 300 feet, completed in unknown year. The 10 tallest Ohio dams from the National Inventory of Dams:
| Dam | Height | Year | Primary Purpose | Condition | County |
|---|---|---|---|---|---|
| No. 2 Slurry Pond | 300 ft | – | Water Supply | Not Available | Belmont |
| The Ohio Valley Coal Slurry Disposal Dam | 275 ft | 1981 | Tailings | Not Rated | Belmont |
| Cardinal Fly Ash No. 2 Dam | 250 ft | 2014 | Tailings | Satisfactory | Jefferson |
| Cardinal Fly Ash No. 1 Dam | 242 ft | 1974 | Tailings | Satisfactory | Jefferson |
| William H. Harsha Dam | 205 ft | 1973 | Flood Risk Reduction | Not Available | Clermont |
| Caesar Creek Dam | 180 ft | 1976 | Flood Risk Reduction | Not Available | Warren |
| Caesar Creek Dam – Saddle Dike 2 | 180 ft | 1976 | Flood Risk Reduction | Not Available | Warren |
| Caesar Creek Dam – Saddle Dike 3 | 180 ft | 1976 | Flood Risk Reduction | Not Available | Warren |
| Muskingum River Upper Fly Ash Dam | 152 ft | 1975 | Tailings | Fair | Washington |
| Marge Schott Lake Dam | 140 ft | 2000 | Recreation | Satisfactory | Clermont |
High-Hazard Ohio Dams in Poor Condition
The most concerning dams are those classified as high-hazard that also carry a Poor or Unsatisfactory condition rating — 132 dams in Ohio. Notable examples:
- Apple Valley Lake Dam (91 ft, Knox County) — Recreation, Poor condition
- Barnesville Reservoir No. 3 Dam (77 ft, Belmont County) — Water Supply, Poor condition
- Rocky Fork Lake Dam (74 ft, Highland County) — Recreation, Poor condition
- Lake Lakengren Dam (74 ft, Preble County) — Recreation, Poor condition
- Lake Hamilton Dam (70 ft, Mahoning County) — Recreation, Poor condition
Filter the interactive US Dams map by hazard and condition to see all of them on one view.
Dam Safety in Ohio
Dam safety in Ohio is overseen by the state dam safety program, in coordination with federal regulators: the US Army Corps of Engineers, the Bureau of Reclamation (for federal water projects), the Tennessee Valley Authority where applicable, and the Federal Energy Regulatory Commission (FERC) for licensed hydropower dams. Emergency Action Plans are typically required for high-hazard dams under state regulations.
Frequently Asked Questions
How many dams are in Ohio?
Ohio has 1,402 dams in the National Inventory of Dams tracked by the US Army Corps of Engineers: 421 high hazard, 564 significant hazard, and 340 low hazard.
What is the tallest dam in Ohio?
The tallest dam in Ohio is No. 2 Slurry Pond at 300 feet, completed in unknown year. It is primarily a water supply structure.
How many Ohio dams are in poor condition?
509 Ohio dams are currently rated as being in Poor or Unsatisfactory condition. Of those, 132 are also classified as high-hazard — meaning failure would likely cause loss of life.
