Johnson Lake Dam Reservoir Report

Last Updated: December 5, 2025

Johnson Lake Dam, also known as Floyds Lake Dam, is a private earth dam located in Henry, Georgia.


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Summary

Completed in 1954, the dam stands at a height of 15 feet and has a length of 580 feet, creating a reservoir with a storage capacity of 112.5 acre-feet. The primary purpose of this dam is for recreation, providing a serene spot for water resource and climate enthusiasts to enjoy.

Despite being classified as having low hazard potential, Johnson Lake Dam is subject to regular inspections, with the last one conducted in March 2017. With a moderate risk assessment rating of 3, there are currently no emergency action plans in place for the dam. The dam features uncontrolled spillways and outlets, and is not regulated or permitted by the state, posing a moderate level of risk that may be of interest to water resource and climate enthusiasts in the area.

For those interested in exploring the water infrastructure of Georgia, Johnson Lake Dam offers a glimpse into the engineering and environmental considerations of private dams. With its peaceful surroundings and recreational opportunities, this dam serves as a focal point for both enjoyment and study in the realm of water resources and climate impact mitigation.

Year Completed

1954

Dam Length

580

Dam Height

15

River Or Stream

UNKNOWN

Primary Dam Type

Earth

Surface Area

14

Drainage Area

340

Nid Storage

112.5

Outlet Gates

Uncontrolled

Hazard Potential

Low

Foundations

Unlisted/Unknown

Nid Height

15
       
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.