Alcyon Lake Dam Reservoir Report

Last Updated: December 13, 2025

Alcyon Lake Dam, located in Pitman, New Jersey, is a structure primarily owned and regulated by the local government.


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Summary

Built in 1943, this earth dam serves the purpose of recreation, providing a picturesque setting for outdoor activities in the surrounding area. With a height of 12 feet and a length of 480 feet, the dam has a storage capacity of 150 acre-feet and covers a surface area of 19 acres.

Managed by the New Jersey Department of Environmental Protection (NJDEP), Alcyon Lake Dam is deemed to have significant hazard potential, yet is currently assessed to be in fair condition as of March 2020. The dam is inspected every two years to ensure its structural integrity and safety. In the event of an emergency, an Emergency Action Plan (EAP) may be implemented to mitigate risks and protect downstream areas from potential inundation.

The Chestnut Branch Mantua Creek flows through this region, contributing to a drainage area of 4 square miles. The dam's maximum discharge capacity is 632 cubic feet per second, providing essential flood control measures for the surrounding community. As a popular recreational spot, Alcyon Lake Dam serves as both a functional water resource structure and a scenic destination for visitors to enjoy nature's beauty while also appreciating the vital role dams play in water management and climate resilience.

Year Completed

1943

Dam Length

480

Dam Height

12

River Or Stream

Chestnut Branch Mantua Creek

Primary Dam Type

Earth

Surface Area

19

Drainage Area

4

Nid Storage

150

Hazard Potential

Significant

Nid Height

12
       
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.