St. Stephen Powerhouse Dam Reservoir Report

Last Updated: December 15, 2025

The St.


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Summary

Stephen Powerhouse Dam, also known as Lake Moultrie, is a concrete dam completed in 1985 in St. Stephen, South Carolina. Owned and managed by the US Army Corps of Engineers, the dam serves primarily for navigation purposes on the Cooper/Santee River system. With a structural height of 128 feet and a capacity of 2,560,000 acre-feet, the dam plays a crucial role in flood risk reduction, hydroelectric power generation, and recreational activities.

Despite being classified as having a high hazard potential, the risk assessment for the St. Stephen Powerhouse Dam is considered low overall. The dam's location and design minimize the potential impact of a failure, with only minor flooding expected in downstream areas during a large earthquake event. To mitigate risks further, the USACE implements various risk management measures, including regular inspections, emergency action plans, and training for project personnel. Additionally, flood fighting supplies are stocked on-site for immediate response in case of an emergency, ensuring the safety and security of the surrounding communities and water resources.

Year Completed

1985

Dam Length

965

Dam Height

128

River Or Stream

COOPER/SANTEE

Primary Dam Type

Concrete

Hydraulic Height

75

Drainage Area

15000

Nid Storage

2560000

Structural Height

128

Outlet Gates

Vertical Lift - 0

Hazard Potential

High

Foundations

Rock

Nid Height

128
       
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.