Horsethief Lake
Horsethief Lake is an earth dam located in Pennington County, South Dakota, built in 1940. It carries a High hazard potential classification.
About Horsethief Lake
The primary purpose of Horsethief 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 Pine Creek near Keystone.
The dam stands 65 feet tall and stretches 325 feet across, has a maximum storage capacity of 590 acre-feet, and collects water from a drainage area of 4 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 09/27/2019.
At 65 feet, this dam is taller than 96% 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 | Pennington |
| Nearest City | Keystone |
| River/Stream | Pine Creek |
| Coordinates | 43.89438, -103.47964 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 65 ft |
| Dam Height | 62 ft |
| Dam Length | 325 ft |
| Year Completed | 1940 (86 years old) |
Storage & Hydraulics
| NID Storage | 590 acre-ft |
| Max Storage | 590 acre-ft |
| Normal Storage | 464 acre-ft |
| Drainage Area | 4 sq mi |
| Max Discharge | 990 cfs |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Recreation |
| Owner | USDA FS |
| Owner Type | Federal |
| Hazard Classification | High |
| Condition Assessment | Not Rated |
| Last Inspection | 09/27/2019 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | SD01118 |
| Federal ID | SD01118 |
| More Info | State Dam Safety Program |