Reliance Dam is an earth dam located in Lyman County, South Dakota, built in 1935. It carries a Significant hazard potential classification.
Dam profile
NID height · 16 ft16 ft tall and 525 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 Reliance Dam
The primary purpose of Reliance Dam is recreation. The dam creates a reservoir used for recreational activities such as fishing, boating, and swimming. The dam is owned by Town of Reliance (local government). It impounds the American Crow Creek near Oacoma.
The dam stands 16 feet tall and stretches 525 feet across, creates a reservoir covering 46 acres, has a maximum storage capacity of 530 acre-feet, and collects water from a drainage area of 15 square miles. Completed in 1935, the structure is well-established, with more than 75 years of service.
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. The most recent inspection on record was 12/21/2023.
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Location
| State | South Dakota |
| County | Lyman |
| Nearest City | Oacoma |
| River/Stream | American Crow Creek |
| Coordinates | 43.88115, -99.59288 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 16 ft |
| Dam Height | 16 ft |
| Dam Length | 525 ft |
| Year Completed | 1935 (91 years old) |
Storage & Hydraulics
| NID Storage | 530 acre-ft |
| Max Storage | 530 acre-ft |
| Normal Storage | 235 acre-ft |
| Surface Area | 46 acres |
| Drainage Area | 15 sq mi |
| Max Discharge | 1,425 cfs |
Ownership & Safety
| Purpose | Recreation |
| Owner | Town of Reliance |
| Owner Type | Local Government |
| Hazard Classification | Significant |
| Condition Assessment | Not assessed |
| Last Inspection | 12/21/2023 |
| Emergency Action Plan | Not Required |
Identifiers
| NID ID | SD02168 |
| Federal ID | SD02168 |
| More Info | State Dam Safety Program |