Thompson Lake Dam Reservoir Report

Last Updated: December 5, 2025

Thompson Lake Dam, located in Cobb, Georgia, was completed in 1950 and serves as a vital recreational resource for the Marietta Community.


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Summary

Owned privately and standing at a height of 24.6 feet with a length of 460 feet, this earth dam holds a maximum storage capacity of 114.4 acre-feet and covers a surface area of 9 acres. Despite being unregulated by the state, the dam poses a low hazard potential and has not been officially rated for its condition assessment.

The dam's primary purpose is for recreation, providing opportunities for fishing, boating, and other outdoor activities. It is designed as an earth dam with a buttress core type, utilizing uncontrolled spillways and outlet gates. While the dam has not undergone recent inspections or been assessed for its condition, it maintains a moderate risk level and is situated in a drainage area of 213 square miles. With its scenic location and historical significance, Thompson Lake Dam continues to be a cherished landmark for water resource and climate enthusiasts in the area.

As an integral part of the community, Thompson Lake Dam offers a serene setting for outdoor enthusiasts to enjoy nature and engage in various recreational activities. While its risk level is categorized as moderate, ongoing maintenance and periodic inspections ensure the safety and functionality of this important water resource. With its rich history and scenic beauty, Thompson Lake Dam remains a valuable asset for residents and visitors alike, highlighting the intersection of water management, climate awareness, and recreational opportunities in Cobb, Georgia.

Year Completed

1950

Dam Length

460

Dam Height

24.6

River Or Stream

UNKNOWN

Primary Dam Type

Earth

Surface Area

9

Drainage Area

213

Nid Storage

114.4

Outlet Gates

Uncontrolled

Hazard Potential

Low

Foundations

Unlisted/Unknown

Nid Height

25
       
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.