Felsenthal Lock And Dam Reservoir Report

Last Updated: December 5, 2025

Felsenthal Lock and Dam, located in Union, Arkansas, is a gravity dam constructed by the US Army Corps of Engineers in 1978 for the primary purpose of navigation on the Ouachita River.


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Summary

With a structural height of 105 feet and a hydraulic height of 36 feet, the dam spans 659 feet in length and has a storage capacity of 76,700 acre-feet. The dam also serves purposes of recreation and water supply, covering a surface area of 22,730 acres and draining a watershed area of 10,782 square miles.

With a controlled spillway and one lock measuring 600 feet in length and 84 feet in width, Felsenthal Lock and Dam poses a significant hazard potential due to its very high risk assessment for flooding. The US Army Corps of Engineers actively manages dam-related flood risks by monitoring the dam's condition, prioritizing risk-reducing activities, and engaging with emergency managers and the public to raise awareness and preparedness for potential emergencies. Regular maintenance and updates to the emergency action plan are key components of the risk management measures implemented by the USACE to ensure the safety and integrity of Felsenthal Lock and Dam.

Year Completed

1978

Dam Length

659

River Or Stream

OUACHITA

Primary Dam Type

Gravity

Surface Area

22730

Length Of Locks

600

Hydraulic Height

36

Drainage Area

10782

Nid Storage

76700

Structural Height

105

Hazard Potential

Significant

Foundations

Soil

Nid Height

105
       
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.