Ponca Right Dike
Ponca Right Dike is an earth dam located in Gregory County, South Dakota, built in 1994. It carries a High hazard potential classification and has a satisfactory condition assessment.
About Ponca Right Dike
The primary purpose of Ponca Right Dike 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 Bia (federal). It impounds the Willow Creek.
The dam stands 15 feet tall and stretches 130 feet across, has a maximum storage capacity of 828 acre-feet, and collects water from a drainage area of 9 square miles. Completed in 1994, the structure is 32 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. 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 08/06/2020.
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 | Gregory |
| Nearest City | None |
| River/Stream | Willow Creek |
| Coordinates | 43.06097, -99.14477 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 15 ft |
| Dam Height | 15 ft |
| Dam Length | 130 ft |
| Year Completed | 1994 (32 years old) |
Storage & Hydraulics
| NID Storage | 828 acre-ft |
| Max Storage | 828 acre-ft |
| Drainage Area | 9 sq mi |
| Max Discharge | 30,200 cfs |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Flood Risk Reduction |
| Owner | BIA |
| Owner Type | Federal |
| Hazard Classification | High |
| Condition Assessment | Satisfactory |
| Last Inspection | 08/06/2020 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | SD00545 |
| Federal ID | SD00545S001 |
| More Info | State Dam Safety Program |