Iona Lake Dam Reservoir Report

Last Updated: December 5, 2025

Iona Lake Dam, located in Franklin Township, New Jersey, is a local government-owned structure primarily designed for recreation purposes.


°F

°F

mph

Wind

%

Humidity

Summary

Situated on the Still Run river, this earth dam stands at a height of 11 feet and spans 800 feet in length, with a storage capacity of 108 acre-feet and a surface area of 60 acres. Despite its recreational focus, the dam also serves important functions in terms of water resource management and climate resilience in the area.

With a significant hazard potential and a poor condition assessment as of the last inspection in March 2021, Iona Lake Dam poses a potential risk to the surrounding community. The dam is regulated by the New Jersey Department of Environmental Protection (NJDEP) and undergoes regular inspections and state enforcement to ensure its safety and functionality. However, there is a need for continued monitoring and potential risk management measures to mitigate any potential hazards associated with the dam.

As a key feature in the local water resource infrastructure, Iona Lake Dam requires ongoing attention and maintenance to ensure its safety and effectiveness in providing recreational opportunities while managing water resources in the region. With its unique location and purpose, the dam serves as a focal point for water resource and climate enthusiasts to engage with the challenges and opportunities of dam management and climate resilience in the area.

Dam Length

800

Dam Height

11

River Or Stream

Still Run

Primary Dam Type

Earth

Surface Area

60

Drainage Area

26.3

Nid Storage

108

Hazard Potential

Significant

Nid Height

11
       
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.