Johnson Dam Reservoir Report

Last Updated: December 5, 2025

Johnson Dam, located in Fauquier, Virginia, along the Great Run stream, is a privately owned earth dam with a primary purpose of recreation.


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Summary

Standing at a height of 24.7 feet and spanning a length of 500 feet, this dam provides a storage capacity of 221.9 acre-feet, with a normal storage level of 131.8 acre-feet. The dam is regulated by the Department of Conservation and Recreation in Virginia, ensuring that it meets state inspection, permitting, and enforcement standards.

Despite its undetermined hazard potential and lack of a current condition rating, Johnson Dam remains a popular spot for water resource and climate enthusiasts seeking recreational opportunities in the area. With a surface area of 17 acres and a drainage area of 1.25 square miles, the dam offers a tranquil setting for outdoor activities such as fishing, boating, and wildlife observation. While the dam's last inspection dates back to 2009, its emergency action plan was last revised in 2003, indicating a need for updated risk assessment and management measures.

Overall, Johnson Dam presents an intriguing blend of natural beauty and recreational potential for visitors to enjoy. As a part of the Baltimore District, the dam's location along the Great Run stream adds to its appeal for those interested in exploring water resources and climate dynamics in the region. While its current condition and hazard potential remain uncertain, the dam's historical significance and scenic surroundings make it a noteworthy destination for outdoor enthusiasts looking to connect with nature.

Dam Length

500

Dam Height

24.7

River Or Stream

Great Run

Primary Dam Type

Earth

Surface Area

17

Hydraulic Height

24.7

Drainage Area

1.25

Nid Storage

221.9

Structural Height

24.7

Hazard Potential

Undetermined

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.
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