Hershey Mill Reservoir Report

Last Updated: December 5, 2025

Hershey Mill is a historic earth dam located in Chester, Pennsylvania, constructed in 1748 for recreational purposes along the Ridley Creek.


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Summary

With a height of 14 feet and a length of 450 feet, the dam has a storage capacity of 18 acre-feet and a surface area of 7 acres. Despite its age, the dam is regulated by the Pennsylvania Department of Environmental Protection and has undergone inspections, with a hazard potential rated as significant and a fair condition assessment.

Located in East Goshen Township, Hershey Mill is a popular spot for outdoor activities and offers a serene setting for visitors to enjoy. The dam's primary purpose is for recreation, and it is owned and regulated by the local government. The dam's fair condition and regular inspections ensure that it continues to provide a safe and enjoyable environment for water resource and climate enthusiasts to appreciate.

As an important water resource in the area, Hershey Mill plays a vital role in the local ecosystem and provides a picturesque backdrop for those seeking to connect with nature. Its historical significance and recreational value make it a cherished landmark in Chester, Pennsylvania, attracting visitors who appreciate the beauty and tranquility of this man-made structure along the Ridley Creek.

Year Completed

1748

Dam Length

450

Dam Height

14

River Or Stream

RIDLEY CREEK

Primary Dam Type

Earth

Surface Area

7

Drainage Area

1.8

Nid Storage

18

Hazard Potential

Significant

Foundations

Unlisted/Unknown

Nid Height

14
       
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.