Manahawkin Lake Dam Reservoir Report
Nearby: Oxycocus East Dike #1 Cedar Run Dam
Last Updated: December 9, 2025
Manahawkin Lake Dam, located in Manahawkin, New Jersey, is a crucial structure managed by the local government for recreational purposes.
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Summary
Completed in 1929, this Earth dam stands at a height of 12 feet and spans a length of 900 feet, holding a storage capacity of 127 acre-feet. The dam is situated on Mill Creek, within Ocean County, New Jersey, and is regulated by the state agency NJDEP, with regular inspections conducted to ensure its safety and compliance with state regulations.
Despite its historical significance and recreational value, Manahawkin Lake Dam has been assessed to be in poor condition with a significant hazard potential. The last inspection in September 2021 revealed the dam's vulnerability, prompting the need for risk management measures and the preparation of an Emergency Action Plan (EAP). With a drainage area of 19.7 square miles and a surface area of 54 acres, any failure of the dam could lead to severe consequences, underscoring the importance of regular maintenance and monitoring to safeguard the surrounding community.
As a focal point of the Stafford Township, Manahawkin Lake Dam serves not only as a recreational spot but also as a critical infrastructure in need of attention and mitigation strategies to address its current condition. With the collaboration of state agencies and local authorities, efforts are underway to ensure the long-term safety and resilience of this dam, balancing the need for recreation with the imperative of public safety in the face of potential climate-related challenges.
Year Completed |
1929 |
Dam Length |
900 |
Dam Height |
12 |
River Or Stream |
Mill Creek |
Primary Dam Type |
Earth |
Surface Area |
54 |
Drainage Area |
19.7 |
Nid Storage |
127 |
Hazard Potential |
Significant |
Nid Height |
12 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
Dam Data Reference
Condition Assessment
SatisfactoryNo 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
HighDams 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.
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