Swatara Reservoir Report

Last Updated: December 8, 2025

Located in Derry Township, Dauphin County, Pennsylvania, Swatara Dam stands as a vital water supply structure with a primary purpose of ensuring a steady water source for the region.


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Summary

Built in 1935, this concrete dam spans 360 feet in length and reaches a height of 10 feet, holding a maximum storage capacity of 668.6 acre-feet and a normal storage capacity of 501.4 acre-feet. Situated on the Swatara Creek, the dam serves as a crucial infrastructure regulated by the Pennsylvania Department of Environmental Protection.

With a low hazard potential and a condition assessment that is currently not rated, Swatara Dam undergoes inspections every five years to ensure its structural integrity and operational efficiency. Even though there are no associated structures, the dam provides essential water supply services to the surrounding area, covering a drainage area of 521 square miles. Despite lacking specific spillway details or hazard management measures, Swatara Dam remains a key component of water resource management in the region, contributing to the sustainability and resilience of the local water supply system.

Year Completed

1935

Dam Length

360

Dam Height

10

River Or Stream

SWATARA CREEK

Primary Dam Type

Concrete

Surface Area

56

Drainage Area

521

Nid Storage

668.6

Hazard Potential

Low

Foundations

Unlisted/Unknown

Nid Height

10
       
Seasonal Comparison

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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.