Pohick Creek Dam #4 Reservoir Report

Last Updated: December 5, 2025

Pohick Creek Dam #4, also known as Lake Royal, is a local government-owned structure located in Fairfax, Virginia.


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Summary

This earth-type dam stands at 42 feet tall and spans 1050 feet, with a primary purpose of flood risk reduction. It is situated along Rabbit Branch and falls under the regulatory authority of the Department of Conservation and Recreation in Virginia.

With a high hazard potential, Pohick Creek Dam #4 has a satisfactory condition assessment as of October 2020. The dam has a maximum storage capacity of 2558 acre-feet and serves as a crucial flood control measure in the region. While its primary function is flood risk reduction, the dam also offers opportunities for recreation, making it a significant asset for both water resource management and community engagement.

Maintaining a strong inspection and enforcement regimen, Pohick Creek Dam #4 ensures the safety of its surrounding areas and residents. With regular inspections and a well-documented emergency action plan, the dam remains a vital component of water resource infrastructure in Fairfax, Virginia. Climate enthusiasts and water resource experts alike can appreciate the critical role this dam plays in mitigating flood risks and protecting the local ecosystem.

Dam Length

1050

Dam Height

42

River Or Stream

Rabbit Branch

Primary Dam Type

Earth

Surface Area

38

Hydraulic Height

42

Drainage Area

3.8

Nid Storage

2558

Structural Height

42

Hazard Potential

High

Nid Height

42
       
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.