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.
Dam profile
NID height · 14 ft14 ft tall and 520 ft long. Height is drawn to scale against a two-story house, about 25 ft; the profile is a generic embankment section and the water level is illustrative.
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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Location
| State | Virginia |
| County | Fairfax |
| River/Stream | Moore Creek |
| Coordinates | 38.81590, -77.40510 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 14 ft |
| Dam Height | 14 ft |
| Dam Length | 520 ft |
Storage & Hydraulics
| NID Storage | 118 acre-ft |
| Max Storage | 118 acre-ft |
| Normal Storage | 83 acre-ft |
| Drainage Area | 1 sq mi |
Ownership & Safety
| Purpose | Recreation |
| Owner | Fairfax County Park Authority;fairfax County Park Authority |
| Owner Type | Local Government |
| Hazard Classification | Significant |
| Condition Assessment | Satisfactory |
| Last Inspection | 04/28/2022 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | VA059011 |
| Federal ID | VA059011 |
| More Info | State Dam Safety Program |