Mystery Valley Lake Dam Reservoir Report

Last Updated: December 5, 2025

Mystery Valley Lake Dam, located in DeKalb, Georgia, is a local government-owned structure designed by the Soil Conservation Service (SCS) with a primary purpose of recreation.


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Summary

Completed in 1960, this earth dam stands at a height of 23.6 feet and has a maximum storage capacity of 200 acre-feet. Despite its age, the dam is in poor condition and has a high hazard potential, with a moderate risk assessment rating.

The dam's inspection frequency is every two years, with the last assessment conducted in January 2021 revealing its poor condition. The dam features uncontrolled spillways and outlet gates, posing potential risks in the event of a significant weather event or natural disaster. It is regulated and inspected by the Georgia Safe Dams Program, indicating a commitment to ensuring the safety and integrity of the structure. With its location in a highly populated area and the potential for significant environmental impact in case of failure, Mystery Valley Lake Dam is a critical infrastructure that requires ongoing monitoring and maintenance to mitigate risks and protect both the community and surrounding ecosystem.

Water resource and climate enthusiasts will find Mystery Valley Lake Dam a fascinating subject for study and advocacy, given its historical significance, recreational importance, and current challenges. Its condition and hazard potential highlight the importance of proactive management and investment in infrastructure to ensure the safety and sustainability of water resources in the face of changing climate conditions. Efforts to address the dam's poor condition and high hazard potential can serve as a model for resilience and adaptation in the face of climate-related risks, emphasizing the critical role of infrastructure in safeguarding communities and ecosystems.

Year Completed

1960

Dam Length

420

Dam Height

23.6

River Or Stream

UNKNOWN

Primary Dam Type

Earth

Surface Area

15

Hydraulic Height

20

Nid Storage

200

Outlet Gates

Uncontrolled

Hazard Potential

High

Foundations

Unlisted/Unknown

Nid Height

24
       
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.