Lake Letterkenny Dam Reservoir Report

Last Updated: December 9, 2025

Lake Letterkenny Dam, located in Franklin, Pennsylvania, was completed in 1945 and serves primarily for recreational purposes.


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Summary

Standing at 16 feet high and spanning 201 feet in length, this stone dam holds a maximum storage capacity of 60 acre-feet with a normal storage level of 48 acre-feet. The dam is situated in Letterkenny Township and regulates the flow of the TR Rocky Spring Branch.

Although the hazard potential of Lake Letterkenny Dam is undetermined and its condition is not rated, it remains a key feature in the region's water resource management. With a federal ownership status and no state regulation or permitting, this dam offers a picturesque setting for outdoor enthusiasts and climate enthusiasts alike. As the dam continues to provide recreational opportunities, it also stands as a reminder of the importance of sustainable water resource management in the face of changing climate patterns.

For water resource and climate enthusiasts, Lake Letterkenny Dam represents a blend of engineering ingenuity and natural beauty. With its historic construction and serene surroundings, this dam serves as a focal point for understanding the intersection of water management, recreational activities, and environmental stewardship. As we navigate the challenges of a changing climate, Lake Letterkenny Dam stands as a testament to the enduring value of protecting our water resources for future generations.

Year Completed

1945

Dam Length

201

Dam Height

16

River Or Stream

TR ROCKY SPRING BRANCH

Primary Dam Type

Stone

Nid Storage

60

Hazard Potential

Undetermined

Foundations

Unlisted/Unknown

Nid Height

16
       
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.