Diamond Mill Pond Dam Reservoir Report
Nearby: Campbells Pond Dam Briant Park Dam
Last Updated: December 9, 2025
Diamond Mill Pond Dam, located in Millburn, New Jersey, along the Rahway River, was completed in 1937 and stands at a height of 9 feet with a length of 375 feet.
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Summary
The primary purpose of this earth dam is for recreational use, offering a serene setting for outdoor enthusiasts to enjoy the surrounding natural beauty. With a storage capacity of 24 acre-feet, the dam provides a normal storage capacity of 11 acre-feet and covers a surface area of 4 acres within a drainage area of 7.1 square miles.
Managed by the local government and regulated by the New Jersey Department of Environmental Protection, Diamond Mill Pond Dam has been assessed to be in fair condition with a significant hazard potential. Regular inspections are conducted, with the most recent one in April 2021, to ensure the safety and integrity of the structure. Despite its age, the dam continues to serve its recreational purpose, attracting visitors to its picturesque location in Essex County. In the event of an emergency, preparations are in place, with an Emergency Action Plan last revised in May 2021.
Congressional District 07's representative, Tom Malinowski, oversees the area where Diamond Mill Pond Dam is situated, emphasizing the importance of maintaining and monitoring the dam for the safety and enjoyment of the community. As a vital part of the local water resource infrastructure, the dam plays a crucial role in flood control and water management along the Rahway River. With its historical significance and ongoing maintenance efforts, Diamond Mill Pond Dam remains a key feature in the region's natural landscape, offering both recreational opportunities and environmental benefits for residents and visitors alike.
Year Completed |
1937 |
Dam Length |
375 |
Dam Height |
9 |
River Or Stream |
Rahway River |
Primary Dam Type |
Earth |
Surface Area |
4 |
Drainage Area |
7.1 |
Nid Storage |
24 |
Hazard Potential |
Significant |
Nid Height |
9 |
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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