Big Bend Dam
Big Bend Dam is an earth dam located in Lyman County, South Dakota, built in 1963. It carries a High hazard potential classification.
About Big Bend Dam
The primary purpose of Big Bend Dam is flood risk reduction. The dam is designed to control downstream flooding by temporarily storing excess water during storms and releasing it at a controlled rate. The dam is owned by Usace - Omaha District (federal). It impounds the Missouri River near Chamberlain.
The dam stands 205 feet tall and stretches 10,570 feet across, creates a reservoir covering 60,000 acres, has a maximum storage capacity of 1,900,000 acre-feet, and collects water from a drainage area of 5,840 square miles. Completed in 1963, the structure is well into its service life at over 50 years old.
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 06/03/2024.
At 205 feet, this dam is taller than 99% of all dams in the United States.
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 Dakota 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 Dakota |
| County | Lyman |
| Nearest City | Chamberlain |
| River/Stream | Missouri River |
| Coordinates | 44.04170, -99.44453 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 205 ft |
| Dam Height | 96 ft |
| Dam Length | 10,570 ft |
| Year Completed | 1963 (63 years old) |
Storage & Hydraulics
| NID Storage | 1,900,000 acre-ft |
| Max Storage | 1,900,000 acre-ft |
| Normal Storage | 1,725,000 acre-ft |
| Surface Area | 60,000 acres |
| Drainage Area | 5,840 sq mi |
| Max Discharge | 390,000 cfs |
| Spillway Type | Controlled |
Ownership & Safety
| Purpose | Flood Risk Reduction |
| Owner | USACE - Omaha District |
| Owner Type | Federal |
| Hazard Classification | High |
| Condition Assessment | Not Available |
| Last Inspection | 06/03/2024 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | SD01092 |
| Federal ID | SD01092 |
| More Info | State Dam Safety Program |