Jocassee Spillway Reservoir Report

Last Updated: December 6, 2025

Jocassee Spillway, located in Clemson, South Carolina, is a key structure owned by a public utility and primarily regulated by the Federal Energy Regulatory Commission.


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Summary

Completed in 1973, this gravity dam serves the purpose of hydroelectric power generation and stands at a height of 64 feet with a length of 300 feet. The spillway, with a controlled design and a width of 60 feet, is equipped with two Tainter (radial) outlet gates, allowing for a maximum discharge of 43,222.1 cubic feet per second.

With a storage capacity of 1,160,298 acre-feet and a surface area of 7,565 acres, Jocassee Spillway plays a crucial role in managing the Keowee River's flow. The dam's hazard potential is classified as high, and the risk assessment rates it as very high (1), underscoring the importance of its management and maintenance. Despite its structural significance and operational capacity, the condition assessment of Jocassee Spillway is currently not available, highlighting the need for ongoing monitoring and evaluation to ensure its continued safety and reliability for water resource and climate enthusiasts.

As a prominent feature in the Nashville District, Jocassee Spillway is a testament to engineering excellence and environmental stewardship. Its association with two other structures underscores its interconnectedness within the region's water infrastructure. With Congressman Jeff Duncan (R) as the local representative, the spillway's role in supporting energy production, water management, and flood control in Oconee County, South Carolina, showcases its multifaceted contributions to the community and the surrounding ecosystem.

Year Completed

1973

Dam Length

300

Dam Height

64

River Or Stream

Keowee

Primary Dam Type

Gravity

Surface Area

7565

Hydraulic Height

64

Nid Storage

1160298

Structural Height

64

Outlet Gates

Tainter (radial) - 2

Hazard Potential

High

Foundations

Rock

Nid Height

64
       
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.