Patterson Reservoir Report

Last Updated: December 6, 2025

Patterson is a historic hydroelectric dam located in Beaver Falls, Pennsylvania, along the Beaver River.


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Summary

Built in 1825, this Timber Crib dam stands at 14 feet high and spans 700 feet in length, providing a storage capacity of 380 acre-feet and a maximum discharge of 60,000 cubic feet per second. The dam, regulated by the Federal Energy Regulatory Commission, serves primarily for hydroelectric power generation, with a low hazard potential and moderate risk assessment.

Despite its age, Patterson remains in good condition with a low hazard potential, ensuring its continued operational integrity. The dam features an uncontrolled spillway with a width of 550 feet, serving as a critical component of its risk management measures. While the dam's condition assessment is currently marked as "Not Available," regular inspections occur every three years to ensure its safety and reliability. Additionally, Patterson's emergency action plan was last revised in 2013, indicating ongoing efforts to maintain preparedness for any unforeseen events.

Overall, Patterson stands as a testament to early American engineering ingenuity, providing essential hydroelectric power while maintaining a moderate risk level. With its historical significance and operational importance, this Timber Crib dam continues to play a vital role in water resource management and climate resilience in the Beaver Falls region of Pennsylvania.

Year Completed

1825

Dam Length

700

Dam Height

14

River Or Stream

Beaver River

Primary Dam Type

Timber Crib

Surface Area

72

Drainage Area

1981

Nid Storage

380

Hazard Potential

Low

Foundations

Rock

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.