South Twin Lake Dam

South Twin Lake Dam is an earth dam located in Fairfax County, Virginia. It carries a Significant hazard potential classification and has a satisfactory condition assessment.

About South Twin Lake Dam

The primary purpose of South Twin Lake Dam is recreation. The dam creates a reservoir used for recreational activities such as fishing, boating, and swimming. The dam is owned by Fairfax County Park Authority;fairfax County Park Authority (local government). It impounds the Moore Creek.

The dam stands 14 feet tall and stretches 520 feet across, has a maximum storage capacity of 118 acre-feet, and collects water from a drainage area of 1 square miles.

This dam has a significant hazard potential classification, meaning that a failure could cause significant economic damage — flooding roads, bridges, or property downstream — but is not expected to result in loss of life. Its condition is rated satisfactory, indicating no existing or potential dam safety deficiencies are recognized. An emergency action plan is in place for this dam. The most recent inspection on record was 04/28/2022.

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Significant HazardSatisfactory ConditionEmergency Action Plan: Yes

Location

StateVirginia
CountyFairfax
River/StreamMoore Creek
Coordinates38.81590, -77.40510

Physical Characteristics

Dam TypeEarth
NID Height14 ft
Dam Height14 ft
Dam Length520 ft

Storage & Hydraulics

NID Storage118 acre-ft
Max Storage118 acre-ft
Normal Storage83 acre-ft
Drainage Area1 sq mi

Ownership & Safety

PurposeRecreation
OwnerFairfax County Park Authority;Fairfax County Park Authority
Owner TypeLocal Government
Hazard ClassificationSignificant
Condition AssessmentSatisfactory
Last Inspection04/28/2022
Emergency Action PlanYes

Identifiers

NID IDVA059011
Federal IDVA059011
More InfoState Dam Safety Program

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