Parsippany Dike Reservoir Report

Last Updated: December 11, 2025

Parsippany Dike, located in Morris County, New Jersey, is a critical structure managed by the local government for water supply purposes.


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Summary

This masonry dam, completed in 1905, stands at a height of 30 feet and spans a length of 2150 feet along the Rockaway River. With a normal storage capacity of 28,000 acre-feet and covering a surface area of 800 acres, the dam plays a vital role in regulating water flow and ensuring a stable water supply for the region.

Despite its age, Parsippany Dike has been assessed as being in satisfactory condition, with a high hazard potential. Regular inspections, with the last one conducted in July 2021, ensure that the dam meets safety standards and is well-maintained. The dam is regulated by the New Jersey Department of Environmental Protection, with state oversight for permitting, inspection, and enforcement to ensure its continued safe operation.

In the event of an emergency, there is a need for an emergency action plan (EAP) to guide response and mitigate risks. While the EAP status and adherence to guidelines are not specified in the data, ongoing assessments and risk management measures are essential to protect the surrounding community and infrastructure. As water resource and climate enthusiasts, understanding the importance of structures like Parsippany Dike highlights the interconnectedness of water management, infrastructure resilience, and emergency preparedness in safeguarding our environment and communities.

Year Completed

1905

Dam Length

2150

Dam Height

30

River Or Stream

Rockaway River

Primary Dam Type

Masonry

Surface Area

800

Drainage Area

119

Nid Storage

28000

Hazard Potential

High

Nid Height

30
       
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.