Great Falls Reservoir Report

Last Updated: December 10, 2025

Great Falls, also known as S.U.M.


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Summary

Dam, is a historic masonry dam located on the Passaic River in Paterson, New Jersey. Completed in 1840, this dam serves a primary purpose of hydroelectric power generation, utilizing its gravity and masonry construction to harness the river's energy. With a height of 12 feet and a length of 325 feet, Great Falls has a storage capacity of 1,415 acre-feet and a maximum discharge of 23,500 cubic feet per second.

Managed by the local government and regulated by the New Jersey Department of Environmental Protection and the Federal Energy Regulatory Commission, Great Falls is inspected every three years to ensure its structural integrity. Despite its low hazard potential, the dam poses a moderate risk due to its age and the surrounding area's susceptibility to climate-related events. While its condition assessment is currently not available, emergency action plans have been prepared and updated periodically to mitigate any potential risks and ensure public safety in case of emergencies.

Great Falls stands as a testament to the intersection of water resource management and climate resilience, highlighting the importance of maintaining and monitoring critical infrastructure in the face of changing environmental conditions. As a key player in the local hydroelectric power generation industry, this historic dam continues to play a significant role in harnessing renewable energy sources and supporting sustainable development in the region.

Year Completed

1840

Dam Length

325

Dam Height

12

River Or Stream

Passaic River

Primary Dam Type

Masonry

Surface Area

202

Drainage Area

785

Nid Storage

1415

Hazard Potential

Low

Foundations

Rock

Nid Height

12
       
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.