Mountain Valley Park Dam
Mountain Valley Park Dam is an earth dam located in Morris County, New Jersey, built in 1950. It carries a Significant hazard potential classification and has a satisfactory condition assessment.
About Mountain Valley Park Dam
The primary purpose of Mountain Valley Park 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 Mendham (local government). It impounds the North Branch Raritan River near Mendham Township.
The dam stands 10 feet tall and stretches 160 feet across, creates a reservoir covering 1 acres, has a storage capacity of 20 acre-feet, and collects water from a drainage area of 1 square miles. Completed in 1950, 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 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 05/12/2025.
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Location
| State | New Jersey |
| County | Morris |
| Nearest City | Mendham Township |
| River/Stream | North Branch Raritan River |
| Coordinates | 40.78578, -74.60785 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 10 ft |
| Dam Height | 10 ft |
| Dam Length | 160 ft |
| Year Completed | 1950 (76 years old) |
Storage & Hydraulics
| NID Storage | 20 acre-ft |
| Normal Storage | 20 acre-ft |
| Surface Area | 1 acres |
| Drainage Area | 1 sq mi |
| Max Discharge | 500 cfs |
Ownership & Safety
| Purpose | Recreation |
| Owner | Borough of Mendham |
| Owner Type | Local Government |
| Hazard Classification | Significant |
| Condition Assessment | Satisfactory |
| Last Inspection | 05/12/2025 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | NJ00953 |
| Federal ID | NJ00953 |
| More Info | State Dam Safety Program |