William H. Harsha Dam is a rockfill dam located in Clermont County, Ohio, built in 1973. It carries a High hazard potential classification.
Dam profile
NID height · 205 ft205 ft tall and 1,450 ft long, taller than 99% of U.S. dams with a recorded height. Height is drawn to scale against the Statue of Liberty, 305 ft ground to torch; the profile is a generic rockfill embankment section and the water level is illustrative.
About William H. Harsha Dam
The primary purpose of William H. Harsha Dam is flood risk reduction. The dam is designed to control downstream flooding by temporarily storing excess water during storms and releasing it at a controlled rate. The dam is owned by USACE - Louisville District (federal). It impounds the East Fork of Little Miami near Batavia.
The dam stands 205 feet tall and stretches 1,450 feet across, creates a reservoir covering 2,160 acres, has a maximum storage capacity of 294,800 acre-feet, and collects water from a drainage area of 342 square miles. Completed in 1973, the structure is well into its service life at over 50 years old.
This dam carries a high hazard potential classification, which means that a failure or uncontrolled release of water would likely cause loss of human life. This classification reflects the consequences of failure, not the likelihood — it indicates that people live or work in the area downstream. An emergency action plan is in place for this dam. The most recent inspection on record was 07/21/2025.
At 205 feet, this dam is taller than 99% of all dams in the United States.
Living Downstream
If you live or work downstream of this dam, consider taking these steps: learn your local evacuation routes, check whether your county emergency management office has a dam failure inundation map, and sign up for local emergency alerts. The Ohio dam safety program can provide more specific information about emergency planning for this structure.
Search for dams near your address to see all dams in your area with hazard classifications and safety data.
Location
| State | Ohio |
| County | Clermont |
| Nearest City | Batavia |
| River/Stream | East Fork of Little Miami |
| Coordinates | 39.02278, -84.15056 |
Physical Characteristics
| Dam Type | Rockfill |
| NID Height | 205 ft |
| Dam Length | 1,450 ft |
| Year Completed | 1973 (53 years old) |
Storage & Hydraulics
| NID Storage | 294,800 acre-ft |
| Max Storage | 294,800 acre-ft |
| Normal Storage | 92,600 acre-ft |
| Surface Area | 2,160 acres |
| Drainage Area | 342 sq mi |
| Max Discharge | 211,000 cfs |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Flood Risk Reduction |
| Owner | USACE - Louisville District |
| Owner Type | Federal |
| Hazard Classification | High |
| Condition Assessment | Not assessed |
| Last Inspection | 07/21/2025 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | OH00929 |
| Federal ID | OH00929 |
| More Info | State Dam Safety Program |