Lake Hopatcong Dam Reservoir Report
Last Updated: December 7, 2025
Lake Hopatcong Dam, located in Morris County, New Jersey, is a concrete structure completed in 1925 with a primary purpose of flood risk reduction along the Musconetcong River.
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Summary
Standing at 17 feet high and spanning 271 feet in length, this dam plays a crucial role in managing water levels and protecting the surrounding area from potential flooding events. With a normal storage capacity of 48,209 acre-feet and a surface area of 2,474 acres, the dam serves as a key component in the region's water resource management infrastructure.
Despite its high hazard potential, Lake Hopatcong Dam is currently assessed to be in fair condition, with regular inspections conducted by the New Jersey Department of Environmental Protection to ensure its structural integrity and operational efficiency. The dam's emergency action plan is under review, with updated contact information and guidelines being implemented to enhance emergency preparedness. With a history dating back almost a century, Lake Hopatcong Dam remains a critical asset for flood control and water management in the area, serving as a testament to the importance of maintaining and monitoring our water resources in the face of changing climate conditions.
As climate change continues to impact water resources and extreme weather events become more frequent, the role of structures like Lake Hopatcong Dam in mitigating flood risks and safeguarding communities becomes increasingly vital. With ongoing assessments and maintenance efforts in place, this concrete dam stands as a testament to the commitment to ensuring the safety and resilience of our water infrastructure in the face of evolving environmental challenges. As water resource and climate enthusiasts, understanding the significance of Lake Hopatcong Dam highlights the intersection of engineering, policy, and environmental stewardship in safeguarding our waterways for future generations.
Year Completed |
1925 |
Dam Length |
271 |
Dam Height |
17 |
River Or Stream |
Musconetcong River |
Primary Dam Type |
Concrete |
Surface Area |
2474 |
Drainage Area |
25.4 |
Nid Storage |
48209 |
Hazard Potential |
High |
Nid Height |
17 |
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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