Watchung Lake Dam Reservoir Report

Last Updated: December 7, 2025

Watchung Lake Dam, located in Watchung Borough, New Jersey, is a local government-owned structure that serves primarily for recreational purposes.


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Summary

This Earth-type dam spans 420 feet in length and stands at a height of 19.2 feet, impounding the waters of the Stony Brook West Branch. With a normal storage capacity of 93 acre-feet and a maximum discharge rate of 3133 cubic feet per second, the dam presents a high hazard potential but was assessed to be in satisfactory condition as of May 2021.

Managed by the New Jersey Department of Environmental Protection (NJDEP), Watchung Lake Dam undergoes regular inspections every two years to ensure its structural integrity and safety. The dam's emergency action plan (EAP) was last revised in August 2021, emphasizing preparedness and risk management measures in case of a potential breach or flooding event. The dam's location within Somerset County further highlights its significance in water resource management and climate resilience efforts in the region, under the regulatory oversight of NJDEP.

As a crucial infrastructure asset in the area, Watchung Lake Dam not only provides recreational opportunities but also contributes to water storage and flood control measures. With its strategic placement and high hazard potential, ongoing monitoring and maintenance efforts are essential to safeguard surrounding communities and the environment from potential risks associated with dam failure. Climate enthusiasts and water resource advocates can closely follow the dam's condition assessments and emergency preparedness updates to support sustainable water management practices and resilience planning in the face of changing climate dynamics.

Dam Length

420

Dam Height

19.2

River Or Stream

Stony Brook West Branch

Primary Dam Type

Earth

Surface Area

16

Drainage Area

3.4

Nid Storage

175

Hazard Potential

High

Nid Height

19
       
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.