Prospertown Dam Reservoir Report

Last Updated: December 8, 2025

Prospertown Dam, located in Upper Freehold Township, New Jersey, is a state-owned structure designed for flood risk reduction along Lahaway Creek.


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Summary

Built in 1966, this earth-type dam stands at a height of 18.5 feet and spans 550 feet in length, with a storage capacity of 490 acre-feet. The dam plays a crucial role in protecting the surrounding area from potential flood events, as it has a high hazard potential and is considered to be in fair condition based on the latest assessment in May 2020.

The dam is regulated by the New Jersey Department of Environmental Protection and is subject to state permitting, inspection, and enforcement. Its primary purpose is flood risk reduction, and it is situated in a picturesque location within Ocean County, New Jersey. With a normal storage capacity of 402 acre-feet and a drainage area of 3.3 square miles, Prospertown Dam serves as a vital infrastructure asset in managing water resources and mitigating flood risks in the region.

Despite its age, Prospertown Dam continues to stand as a key piece of infrastructure in the region, with a storage capacity of 490 acre-feet and the ability to discharge up to 834 cubic feet per second. As a state-regulated structure with a focus on flood risk reduction, the dam's role in protecting the community and managing water resources is essential. Its location in the scenic Upper Freehold Township adds to its significance as a vital component of the local water resource and climate management efforts.

Year Completed

1966

Dam Length

550

Dam Height

18.5

River Or Stream

Lahaway Creek

Primary Dam Type

Earth

Surface Area

70

Drainage Area

3.3

Nid Storage

490

Hazard Potential

High

Nid Height

19
       
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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.