Monongahela River Locks And Dam 3 Reservoir Report

Last Updated: December 5, 2025

Located in Elizabeth, Pennsylvania, Monongahela River Locks and Dam 3, also known as Monongahela River Pool 03, is a federal structure managed by the US Army Corps of Engineers.


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Summary

Completed in 1907, this gravity dam plays a crucial role in navigation along the Monongahela River, with a hydraulic height of 16 feet and two locks that are 720 feet long and 56 feet wide each. The dam has a significant hazard potential and a moderate risk assessment rating, with measures in place to manage flood risks and ensure the structural integrity of the dam.

With a normal storage capacity of 16,300 acre-feet and a drainage area of 5,340 square miles, Monongahela River Locks and Dam 3 provides essential flood control and water management functions. The dam's spillway, with a width of 670 feet, is uncontrolled, allowing for the release of excess water to maintain water levels and protect the dam's integrity during severe weather events. The US Army Corps of Engineers continuously monitors and maintains the dam to address flood risks and collaborates with local emergency managers and the public to ensure readiness and preparedness in case of a dam-related emergency. More detailed information specific to this dam will be added in the future, highlighting the critical role it plays in water resource management and climate resilience efforts in the region.

Year Completed

1907

Dam Length

832

River Or Stream

MONONGAHELA RIVER

Primary Dam Type

Gravity

Surface Area

1590

Length Of Locks

720

Hydraulic Height

16

Drainage Area

5340

Nid Storage

16300

Structural Height

16

Outlet Gates

None - 0, Uncontrolled - 0

Hazard Potential

Significant

Foundations

Soil

Nid Height

16
       
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.