Sunset Lake Dam Reservoir Report

Last Updated: December 9, 2025

Sunset Lake Dam, located in Parsippany, New Jersey, is a historic earth dam completed in 1914 for recreational purposes.


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Summary

Situated on Troy Brook in Morris County, the dam stands at a height of 8.3 feet and has a storage capacity of 90 acre-feet, with a normal storage level of 74 acre-feet. Despite its small surface area of 15 acres and drainage area of 0.37 square miles, the dam has a high hazard potential and is currently in poor condition, as assessed during its last inspection in December 2020.

Owned by the local government, Sunset Lake Dam is regulated by the New Jersey Department of Environmental Protection and is subject to state permitting, inspection, and enforcement. The dam's primary purpose is for recreational use, attracting visitors to its scenic location in Mountain Lakes Borough. With its close proximity to Congressional District 11 and representation by Mikie Sherrill, the dam plays a significant role in the region's water resource management and climate resilience efforts.

As an integral part of the local landscape, Sunset Lake Dam serves as a reminder of the area's history and provides valuable recreational opportunities for residents and visitors alike. However, with its aging infrastructure and high hazard potential, the dam's condition raises concerns for safety and the need for potential risk management measures to ensure the longevity of this important water resource in New Jersey.

Year Completed

1914

Dam Length

165

Dam Height

8.3

River Or Stream

Troy Brook

Primary Dam Type

Earth

Surface Area

15

Drainage Area

0.37

Nid Storage

90

Hazard Potential

High

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.