Duhernal Dam is an earth dam located in Middlesex County, New Jersey, built in 1939. It carries a Significant hazard potential classification and has a poor condition assessment.
Dam profile
NID height · 13 ft13 ft tall and 878 ft long. Height is drawn to scale against a two-story house, about 25 ft; the profile is a generic embankment section and the water level is illustrative.
About Duhernal Dam
The primary purpose of Duhernal Dam is recreation. The dam creates a reservoir used for recreational activities such as fishing, boating, and swimming. The dam is owned by Borough of Sayreville (local government). It impounds the South River near Old Bridge.
The dam stands 13 feet tall and stretches 878 feet across, creates a reservoir covering 195 acres, has a maximum storage capacity of 1,520 acre-feet, and collects water from a drainage area of 94 square miles. Completed in 1939, the structure is well-established, with more than 75 years of service.
This dam has a significant hazard potential classification, meaning that a failure could cause significant economic damage — flooding roads, bridges, or property downstream — but is not expected to result in loss of life. Its condition is rated poor, meaning the dam has recognized safety deficiencies that require remediation to address risks. An emergency action plan is in place for this dam. The most recent inspection on record was 03/10/2025.
Search for dams near your address to see all dams in your area with hazard classifications and safety data.
Location
| State | New Jersey |
| County | Middlesex |
| Nearest City | Old Bridge |
| River/Stream | South River |
| Coordinates | 40.40658, -74.36862 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 13 ft |
| Dam Height | 13 ft |
| Dam Length | 878 ft |
| Year Completed | 1939 (87 years old) |
Storage & Hydraulics
| NID Storage | 1,520 acre-ft |
| Max Storage | 1,520 acre-ft |
| Normal Storage | 780 acre-ft |
| Surface Area | 195 acres |
| Drainage Area | 94 sq mi |
| Max Discharge | 9,000 cfs |
Ownership & Safety
| Purpose | Recreation |
| Owner | Borough of Sayreville |
| Owner Type | Local Government |
| Hazard Classification | Significant |
| Condition Assessment | Poor |
| Last Inspection | 03/10/2025 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | NJ00381 |
| Federal ID | NJ00381 |
| More Info | State Dam Safety Program |