Helmetta Dam Reservoir Report

Last Updated: December 8, 2025

Helmetta Dam, located in Helmetta Borough, New Jersey, is a local government-owned structure on the Manalapan Brook.


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Summary

Primarily used for recreation, this earth and gravity dam stands at 7 feet high and spans 2000 feet in length, with a storage capacity of 64 acre-feet. The dam is regulated by the New Jersey Department of Environmental Protection (NJDEP) and undergoes regular inspections, with its last assessment showing a satisfactory condition as of August 2021.

Despite its modest size, Helmetta Dam is deemed to have significant hazard potential, highlighting the importance of proper maintenance and emergency preparedness. The dam's location within Middlesex County, New Jersey, places it under the jurisdiction of various state agencies, ensuring compliance with all regulatory requirements. With a drainage area of 1.6 square miles and a surface area of 50 acres, the dam plays a crucial role in managing water resources and maintaining the ecological balance of the surrounding area.

As water resource and climate enthusiasts, the Helmetta Dam's role in providing recreational opportunities while safeguarding against potential hazards underscores the delicate balance between human activities and environmental stewardship. Its presence along the Manalapan Brook serves as a reminder of the interconnectedness of our water systems and the need for responsible management practices to mitigate risks and ensure the sustainability of our natural resources.

Dam Length

2000

Dam Height

7

River Or Stream

Manalapan Brook

Primary Dam Type

Earth

Surface Area

50

Drainage Area

1.6

Nid Storage

64

Hazard Potential

Significant

Nid Height

7
       
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.