Big Lake Dam Reservoir Report

Last Updated: December 5, 2025

Big Lake Dam, also known as Mary Dam, is a private-owned structure located in Fauquier, Virginia, along the TR-West Branch river.


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Summary

This earth type dam stands at a height of 29.05 feet and stretches for 480 feet, providing a storage capacity of 74.66 acre-feet for recreational purposes. The dam, constructed for recreation, is regulated and inspected by the Department of Conservation and Recreation in Virginia, ensuring its safety and compliance with state regulations.

While the hazard potential of Big Lake Dam is currently undetermined, its condition assessment is not rated. Emergency action plans have been prepared and last revised in 1998, with a focus on meeting safety guidelines in case of any unforeseen incidents. The dam has not been modified in recent years, and the risk assessment and management measures are yet to be defined. With its picturesque location and essential role in providing recreational opportunities, Big Lake Dam serves as a vital water resource for the community while adhering to state regulatory standards.

Dam Length

480

Dam Height

29.05

River Or Stream

TR-West Branch

Primary Dam Type

Earth

Surface Area

6.69

Hydraulic Height

29.05

Nid Storage

74.66

Structural Height

29.05

Hazard Potential

Undetermined

Nid Height

29
       
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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Area Campgrounds