Gropps Lake Dam Reservoir Report

Last Updated: December 7, 2025

Gropps Lake Dam, located in Bordentown, New Jersey, is a captivating site for water resource and climate enthusiasts.


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Summary

Built in 1900, this earth dam stands at a height of 25 feet and spans a length of 485 feet, creating a reservoir with a storage capacity of 549 acre-feet. The dam serves the primary purpose of recreation, offering a surface area of 41 acres for visitors to enjoy. The surrounding area boasts a drainage area of 7.9 square miles, with Back Creek feeding into the reservoir.

Managed by the local government and regulated by the New Jersey Department of Environmental Protection, Gropps Lake Dam has a low hazard potential and is currently in satisfactory condition. Despite its age, the dam has undergone regular inspections with the last assessment taking place in 2009. With a reassuring condition assessment and a history of safe operation, the dam continues to provide recreational opportunities for residents and visitors alike. Its location in Hamilton Township, within Mercer County, New Jersey, offers a picturesque setting for outdoor activities and wildlife observation.

For those interested in water infrastructure and environmental conservation, Gropps Lake Dam presents a fascinating case study of a historic earth dam that has stood the test of time. With its serene reservoir, ample storage capacity, and regulated maintenance practices, the dam serves as both a recreational haven and a testament to effective dam management. As climate change impacts water resources and infrastructure, Gropps Lake Dam stands as a reminder of the importance of sustainable water management practices in safeguarding our natural ecosystems.

Year Completed

1900

Dam Length

485

Dam Height

25

River Or Stream

Back Creek

Primary Dam Type

Earth

Surface Area

41

Drainage Area

7.9

Nid Storage

549

Hazard Potential

Low

Nid Height

25
       
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.