Holtwood Reservoir Report

Last Updated: December 8, 2025

Holtwood, also known as McCall's Ferry Dam, is a gravity dam located in Lancaster, Pennsylvania along the Susquehanna River.


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Summary

Built in 1910, this hydroelectric structure stands at a height of 55 feet and spans 3,075 feet in length. With a storage capacity of 19,000 acre-feet and a maximum discharge of 800,500 cubic feet per second, Holtwood plays a crucial role in providing hydroelectric power and recreational opportunities in the region.

Managed by a public utility, Holtwood is regulated by the Federal Energy Regulatory Commission and undergoes regular inspections to ensure its safety and functionality. Despite being classified as a low hazard potential structure, Holtwood has a moderate risk assessment level. Although its condition assessment is not available, the dam meets industry guidelines and has an emergency action plan in place to address potential risks. With its scenic location and historical significance, Holtwood is a key contributor to the water resource and climate conservation efforts in the area.

As a significant landmark in the region, Holtwood not only provides renewable energy through hydroelectric power but also offers recreational opportunities for visitors. With its uncontrolled spillway and multi-arch core design, the dam showcases a blend of engineering excellence and environmental stewardship. The moderate risk assessment highlights the importance of ongoing monitoring and management measures to ensure the continued safety and efficiency of this vital water resource infrastructure. For water resource and climate enthusiasts, Holtwood serves as a prime example of sustainable energy generation and responsible dam management practices.

Year Completed

1910

Dam Length

3075

Dam Height

55

River Or Stream

Susquehanna River

Primary Dam Type

Gravity

Surface Area

2400

Drainage Area

26794

Nid Storage

19000

Hazard Potential

Low

Foundations

Rock

Nid Height

55
       
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.