Johnson Dam Reservoir Report
Nearby: Glascock Run Dam Rappahannock Dam #17
Last Updated: December 19, 2025
Johnson Dam, located in Rappahannock, Virginia, is a private-owned earth dam primarily used for recreation on Thumb Run.
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Summary
Standing at a height of 20.13 feet, the dam offers a storage capacity of 53.91 acre-feet with a normal storage level of 44.92 acre-feet. The dam, completed in an undisclosed year, spans 200 feet in length and covers a surface area of 6.32 acres.
Managed by the Department of Conservation and Recreation, Johnson Dam is regulated and inspected by the state of Virginia. While its hazard potential is currently listed as undetermined and its condition assessment as not rated, emergency action plans were last revised in 1997. With its picturesque location and recreational purpose, Johnson Dam serves as a key water resource in the area and offers opportunities for outdoor enthusiasts to enjoy the surrounding natural beauty.
Although specific details about the dam's construction year and maintenance history remain unknown, Johnson Dam stands as a vital water infrastructure in Virginia. With its serene location and storage capacity, the dam provides a valuable resource for both water supply and recreational activities along Thumb Run. As climate change continues to impact water resources, monitoring and assessing the condition of dams like Johnson Dam will be crucial in ensuring their long-term functionality and safety for the surrounding community.
Dam Length |
200 |
Dam Height |
20.13 |
River Or Stream |
Thumb Run |
Primary Dam Type |
Earth |
Surface Area |
6.32 |
Hydraulic Height |
20.13 |
Nid Storage |
53.91 |
Structural Height |
20.13 |
Hazard Potential |
Undetermined |
Nid Height |
20 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
Dam Data Reference
Condition Assessment
SatisfactoryNo 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
HighDams 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.
Johnson Dam