Mountain Valley Park Dam Reservoir Report

Last Updated: December 7, 2025

Mountain Valley Park Dam, located in Mendham Township, New Jersey, is a local government-owned structure designed for recreational purposes.


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Summary

Built in 1950, this Earth-type dam stands at a height of 10 feet and has a length of 160 feet, providing a storage capacity of 20 acre-feet. Situated on the North Branch Raritan River, the dam serves as a vital resource for the community, offering opportunities for outdoor activities and leisure.

Managed by the New Jersey Department of Environmental Protection, the Mountain Valley Park Dam is a regulated and inspected structure, ensuring its safety and compliance with state regulations. With a significant hazard potential but a satisfactory condition assessment, the dam is monitored closely, with inspections conducted every two years to maintain its integrity. Despite its potential risks, the dam remains a valuable asset for the region, contributing to water management and environmental conservation efforts.

As part of Congressional District 11, New Jersey, the Mountain Valley Park Dam plays a crucial role in the local ecosystem and serves as a recreational hub for residents and visitors alike. With its scenic location and strategic importance in water resource management, the dam stands as a testament to the balance between human recreation and environmental stewardship in the face of climate challenges.

Year Completed

1950

Dam Length

160

Dam Height

10

River Or Stream

North Branch Raritan River

Primary Dam Type

Earth

Surface Area

1

Drainage Area

1.1

Nid Storage

20

Hazard Potential

Significant

Nid Height

10
       
Seasonal Comparison

Weather Forecast

Dam Data Reference

Condition Assessment

Satisfactory
No existing or potential dam safety deficiencies are recognized. Acceptable performance is expected under all loading conditions (static, hydrologic, seismic) in accordance with the minimum applicable state or federal regulatory criteria or tolerable risk guidelines.
Fair
No existing dam safety deficiencies are recognized for normal operating conditions. Rare or extreme hydrologic and/or seismic events may result in a dam safety deficiency. Risk may be in the range to take further action. Note: Rare or extreme event is defined by the regulatory agency based on their minimum
Poor A dam safety deficiency is recognized for normal operating conditions which may realistically occur. Remedial action is necessary. POOR may also be used when uncertainties exist as to critical analysis parameters which identify a potential dam safety deficiency. Investigations and studies are necessary.
Unsatisfactory
A dam safety deficiency is recognized that requires immediate or emergency remedial action for problem resolution.
Not Rated
The dam has not been inspected, is not under state or federal jurisdiction, or has been inspected but, for whatever reason, has not been rated.
Not Available
Dams for which the condition assessment is restricted to approved government users.

Hazard Potential Classification

High
Dams assigned the high hazard potential classification are those where failure or mis-operation will probably cause loss of human life.
Significant
Dams assigned the significant hazard potential classification are those dams where failure or mis-operation results in no probable loss of human life but can cause economic loss, environment damage, disruption of lifeline facilities, or impact other concerns. Significant hazard potential classification dams are often located in predominantly rural or agricultural areas but could be in areas with population and significant infrastructure.
Low
Dams assigned the low hazard potential classification are those where failure or mis-operation results in no probable loss of human life and low economic and/or environmental losses. Losses are principally limited to the owner's property.
Undetermined
Dams for which a downstream hazard potential has not been designated or is not provided.
Not Available
Dams for which the downstream hazard potential is restricted to approved government users.