Lower Timber Lake Dike Reservoir Report

Last Updated: December 5, 2025

Lower Timber Lake Dike, located in Fairfax, Virginia, is a private earth dam that serves primarily for recreation purposes, including fish and wildlife pond activities.


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Summary

The dam has a height of 8 feet and a length of 1250 feet, providing a storage capacity of 50.13 acre-feet. The dam regulates the flow of the South Fork Run and covers a surface area of 6.26 acres, making it an essential resource for the local ecosystem and community.

Managed by the Department of Conservation and Recreation, Lower Timber Lake Dike is subject to state regulations, inspections, and enforcement to ensure its safety and functionality. While the hazard potential and condition assessment are currently undetermined and not rated, the dam undergoes regular inspections with an annual frequency to monitor its integrity. Despite the lack of recent modifications or assessments, the dam continues to play a crucial role in providing recreational opportunities and maintaining the ecological balance of the surrounding area.

As climate change and water resource management become increasingly important topics, Lower Timber Lake Dike stands as a significant structure in the region. With its strategic location and purposeful design, the dam exemplifies the intersection of human recreation and environmental conservation. As enthusiasts in water resources and climate, understanding and supporting the upkeep of dams like Lower Timber Lake Dike is essential for the sustainability of our natural ecosystems and recreational spaces.

Dam Length

1250

Dam Height

8

River Or Stream

South Fork Run

Primary Dam Type

Earth

Surface Area

6.26

Hydraulic Height

8

Nid Storage

50.13

Structural Height

8

Hazard Potential

Undetermined

Nid Height

8
       
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.