Manalapan Lake Dam
Manalapan Lake Dam is an earth dam located in Middlesex County, New Jersey. It carries a High hazard potential classification and has a satisfactory condition assessment.
About Manalapan Lake Dam
The primary purpose of Manalapan Lake Dam is recreation. The dam creates a reservoir used for recreational activities such as fishing, boating, and swimming. The dam is owned by County Of Middlesex, Engineering Department (local government). It impounds the Manalapan Brook near Old Bridge.
The dam stands 15 feet tall and stretches 213 feet across, creates a reservoir covering 39 acres, has a maximum storage capacity of 297 acre-feet, and collects water from a drainage area of 25 square miles.
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. Its condition is rated satisfactory, indicating no existing or potential dam safety deficiencies are recognized. An emergency action plan is in place for this dam. The most recent inspection on record was 11/13/2024.
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 New Jersey 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 | New Jersey |
| County | Middlesex |
| Nearest City | Old Bridge |
| River/Stream | Manalapan Brook |
| Coordinates | 40.34717, -74.43508 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 15 ft |
| Dam Height | 15 ft |
| Dam Length | 213 ft |
Storage & Hydraulics
| NID Storage | 297 acre-ft |
| Max Storage | 297 acre-ft |
| Normal Storage | 136 acre-ft |
| Surface Area | 39 acres |
| Drainage Area | 25 sq mi |
| Max Discharge | 2,500 cfs |
Ownership & Safety
| Purpose | Recreation |
| Owner | County of Middlesex, Engineering Department |
| Owner Type | Local Government |
| Hazard Classification | High |
| Condition Assessment | Satisfactory |
| Last Inspection | 11/13/2024 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | NJ00293 |
| Federal ID | NJ00293 |
| More Info | State Dam Safety Program |