Bismark Lake is an earth dam located in Custer County, South Dakota, built in 1937. It carries a High hazard potential classification.
Dam profile
NID height · 40 ft40 ft tall and 280 ft long, taller than 86% of U.S. dams with a recorded height. 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 Bismark Lake
The primary purpose of Bismark Lake is recreation. The dam creates a reservoir used for recreational activities such as fishing, boating, and swimming. The dam is owned by Usda Fs (federal). It impounds the Bismark Creek near Norbeck Wildlife Preserve.
The dam stands 40 feet tall and stretches 280 feet across, has a maximum storage capacity of 626 acre-feet, and collects water from a drainage area of 4 square miles. Completed in 1937, 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 09/27/2019. That was 7 years ago, which is on the longer end for a high-hazard structure.
At 40 feet, this dam is taller than 86% of dams nationwide.
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 | Custer |
| Nearest City | Norbeck Wildlife Preserve |
| River/Stream | Bismark Creek |
| Coordinates | 43.77533, -103.51530 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 40 ft |
| Dam Height | 38 ft |
| Dam Length | 280 ft |
| Year Completed | 1937 (89 years old) |
Storage & Hydraulics
| NID Storage | 626 acre-ft |
| Max Storage | 626 acre-ft |
| Normal Storage | 297 acre-ft |
| Drainage Area | 4 sq mi |
| Max Discharge | 2,087 cfs |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Recreation |
| Owner | Usda Fs |
| Owner Type | Federal |
| Hazard Classification | High |
| Condition Assessment | Not assessed |
| Last Inspection | 09/27/2019 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | SD01116 |
| Federal ID | SD01116 |
| More Info | State Dam Safety Program |