Daley Dam Reservoir Report

Last Updated: December 5, 2025

Daley Dam, also known as Lake Marion, is a private dam located in Loudoun, Virginia, along the TR-Catoctin Creek.


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Summary

This earth dam stands at 29 feet tall with a length of 675 feet, providing a storage capacity of 465 acre-feet. Its primary purpose is for recreation, offering a surface area of 18 acres for water enthusiasts to enjoy.

Managed by the Department of Conservation and Recreation in Virginia, Daley Dam is regulated, permitted, inspected, and enforced by state authorities to ensure its safety and compliance. Despite being classified as having a significant hazard potential, the dam's condition is assessed as fair as of May 2017. Regular inspections are conducted to mitigate risks and maintain the dam's integrity for public safety.

Water resource and climate enthusiasts will appreciate Daley Dam's role in providing recreational opportunities while highlighting the importance of proper dam management and maintenance. With its picturesque location and essential functions, this dam serves as a vital asset in the water infrastructure of Loudoun, Virginia, demonstrating the intersection of human recreation with natural resource management.

Dam Length

675

Dam Height

29

River Or Stream

TR-Catoctin Creek

Primary Dam Type

Earth

Surface Area

18

Hydraulic Height

29

Drainage Area

1.4

Nid Storage

465

Structural Height

29

Hazard Potential

Significant

Nid Height

29
       
Seasonal Comparison

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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.