Lower Twin Lake is an earth dam located in Richland County, South Carolina, built in 1940. It carries a High hazard potential classification.
Dam profile
NID height · 21 ft21 ft tall and 530 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 Lower Twin Lake
The primary purpose of Lower Twin Lake is recreation. The dam creates a reservoir used for recreational activities such as fishing, boating, and swimming. The dam is owned by Fort Jackson (federal). It impounds the Mill Creek near Columbia.
The dam stands 21 feet tall and stretches 530 feet across, creates a reservoir covering 25 acres, has a maximum storage capacity of 650 acre-feet, and collects water from a drainage area of 3 square miles. Completed in 1940, the structure is well-established, with more than 75 years of service.
This dam carries a high hazard potential classification, which means that a failure or uncontrolled release of water would likely cause loss of human life. This classification reflects the consequences of failure, not the likelihood — it indicates that people live or work in the area downstream. An emergency action plan is in place for this dam. The most recent inspection on record was 03/24/2021.
Living Downstream
If you live or work downstream of this dam, consider taking these steps: learn your local evacuation routes, check whether your county emergency management office has a dam failure inundation map, and sign up for local emergency alerts. The South Carolina dam safety program can provide more specific information about emergency planning for this structure.
Search for dams near your address to see all dams in your area with hazard classifications and safety data.
Location
| State | South Carolina |
| County | Richland |
| Nearest City | Columbia |
| River/Stream | Mill Creek |
| Coordinates | 33.99298, -80.90860 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 21 ft |
| Dam Height | 18 ft |
| Dam Length | 530 ft |
| Year Completed | 1940 (86 years old) |
Storage & Hydraulics
| NID Storage | 650 acre-ft |
| Max Storage | 650 acre-ft |
| Normal Storage | 250 acre-ft |
| Surface Area | 25 acres |
| Drainage Area | 3 sq mi |
| Max Discharge | 1,500 cfs |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Recreation |
| Owner | Fort Jackson |
| Owner Type | Federal |
| Hazard Classification | High |
| Condition Assessment | Not assessed |
| Last Inspection | 03/24/2021 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | SC00231 |
| Federal ID | SC00231 |
| More Info | State Dam Safety Program |