Swannanoa Lake #2 (North) Dam Reservoir Report

Last Updated: December 9, 2025

Swannanoa Lake #2 (North) Dam, located in Jefferson Township, New Jersey, was completed in 1914 to serve as a recreational facility for water resource and climate enthusiasts.


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Summary

The dam, with a height of 11 feet and a length of 380 feet, has a storage capacity of 400 acre-feet and covers a surface area of 51 acres. Situated on the Rockaway River, the dam is regulated by the New Jersey Department of Environmental Protection (NJDEP) and undergoes regular inspections to ensure its safety and structural integrity.

Despite being classified as having a high hazard potential, the condition assessment of Swannanoa Lake #2 (North) Dam is rated as satisfactory as of the last inspection in July 2021. The Emergency Action Plan (EAP) for the dam was last revised in December 2021, with no reported incidents or emergencies to date. The dam is primarily used for recreational purposes and offers a tranquil setting for outdoor activities in Morris County, New Jersey. With its historical significance and scenic surroundings, Swannanoa Lake #2 (North) Dam remains a popular destination for visitors and nature enthusiasts alike.

Year Completed

1914

Dam Length

380

Dam Height

11

River Or Stream

Rockaway River

Primary Dam Type

Masonry

Surface Area

51

Drainage Area

13

Nid Storage

400

Hazard Potential

High

Nid Height

11
       
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.