Mirror Lake Dam Reservoir Report

Last Updated: December 6, 2025

Mirror Lake Dam, located in Pemberton Township, New Jersey, is a local government-owned structure that serves primarily for recreation purposes.


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Summary

Built in 1880, this earth-type dam stands at a height of 18 feet and has a length of 750 feet, creating a reservoir with a storage capacity of 2500 acre-feet. Situated on the Rancocas Creek, the dam plays a crucial role in regulating water flow and providing a surface area of 215 acres for recreational activities.

Managed by the New Jersey Department of Environmental Protection, Mirror Lake Dam is state-regulated, inspected, and enforced to ensure its safety and reliability. With a high hazard potential due to its location and size, the dam has been assessed as satisfactory in condition as of April 2021. Regular inspections are conducted every two years to monitor its structural integrity and address any potential risks, ensuring the safety of residents and visitors who enjoy the recreational opportunities offered by the reservoir.

Congressional District 03, represented by Andy Kim, oversees Mirror Lake Dam and its associated structures. The dam's emergency action plan is regularly updated and meets guidelines to ensure preparedness in case of unforeseen events. With its historical significance and role in water resource management and climate resilience, Mirror Lake Dam remains a vital asset in the local community, providing both recreational opportunities and essential water regulation services.

Year Completed

1880

Dam Length

750

Dam Height

18

River Or Stream

Rancocas Creek

Primary Dam Type

Earth

Surface Area

215

Drainage Area

36.7

Nid Storage

2500

Hazard Potential

High

Nid Height

18
       
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.