Island Farm Weir Dam Reservoir Report

Last Updated: December 7, 2025

Island Farm Weir Dam, located in Bridgewater Township, New Jersey, serves as an essential water supply structure on the Raritan River.


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Summary

This concrete gravity dam stands at a height of 8 feet and spans 200 feet, providing a storage capacity of 110 acre-feet and covering a surface area of 60 acres. With a drainage area of 785 square miles and a maximum discharge of 47,000 cubic feet per second, the dam plays a crucial role in managing water resources in the region.

Owned and regulated by the state of New Jersey, Island Farm Weir Dam has been inspected regularly to ensure its satisfactory condition and low hazard potential. The dam's primary purpose is water supply, reflecting its importance in meeting the water needs of the surrounding communities. Despite its modest height and volume, the dam's strategic location and design contribute to its effectiveness in maintaining a reliable water source for both human consumption and environmental sustainability.

As a significant infrastructure on the Raritan River, Island Farm Weir Dam operates under the oversight of the New Jersey Department of Environmental Protection (NJDEP) and complies with state regulations for permitting, inspection, and enforcement. Its critical role in water management, combined with its satisfactory condition and low hazard potential, highlights the dam's importance in ensuring water security and resilience in the face of climate variability and changing hydrological conditions.

Dam Length

200

Dam Height

8

River Or Stream

Raritan River

Primary Dam Type

Concrete

Surface Area

60

Drainage Area

785

Nid Storage

110

Hazard Potential

Low

Nid Height

8
       
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.