Darlington Lake Dam Reservoir Report

Last Updated: December 7, 2025

Darlington Lake Dam, located in Mahwah Township, New Jersey, was completed in 1951 and serves as a key recreational site in the area.


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Summary

Situated on Darlington Brook, this earth dam stands at a height of 19 feet and spans a length of 470 feet. With a storage capacity of 77 acre-feet and a surface area of 26 acres, the dam offers both leisure opportunities and flood control benefits to the community.

Despite its primary purpose of recreation, Darlington Lake Dam poses a significant hazard potential with a poor condition assessment as of July 2019. The dam is regulated by the New Jersey Department of Environmental Protection (NJDEP) and undergoes state inspections and enforcement measures to ensure public safety. While the dam's emergency action plan (EAP) preparation status and risk assessment details are currently unspecified, ongoing efforts are likely in place to address and mitigate potential risks associated with the dam's operation.

As a noteworthy landmark in Bergen County, New Jersey, Darlington Lake Dam remains a focal point for water resource and climate enthusiasts. With its historical significance and environmental impact, the dam's maintenance and risk management efforts are crucial in safeguarding the surrounding community and preserving the natural beauty of the area.

Year Completed

1951

Dam Length

470

Dam Height

19

River Or Stream

Darlington Brook

Primary Dam Type

Earth

Surface Area

26

Drainage Area

2.2

Nid Storage

77

Hazard Potential

Significant

Nid Height

19
       
Seasonal Comparison

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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.