Gregorson No.1 is an earth dam located in Custer County, South Dakota, built in 1973. It carries a Significant hazard potential classification.
Dam profile
NID height · 34 ft34 ft tall and 450 ft long, taller than 78% 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 Gregorson No.1
The primary purpose of Gregorson No.1 is fire protection, stock, or small fish pond. The dam maintains a small impoundment used for fire suppression, livestock watering, or as a fish pond. The dam is owned by Mildred Cline (private). It impounds the Tr-cheyenne.
The dam stands 34 feet tall and stretches 450 feet across, and has a maximum storage capacity of 163 acre-feet. Completed in 1973, the structure is well into its service life at over 50 years old.
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.
At 34 feet, this dam is taller than 78% of dams nationwide.
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Location
| State | South Dakota |
| County | Custer |
| Nearest City | None |
| River/Stream | Tr-cheyenne |
| Coordinates | 43.65333, -103.27166 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 34 ft |
| Dam Height | 34 ft |
| Dam Length | 450 ft |
| Year Completed | 1973 (53 years old) |
Storage & Hydraulics
| NID Storage | 163 acre-ft |
| Max Storage | 163 acre-ft |
| Normal Storage | 93 acre-ft |
| Max Discharge | 2,100 cfs |
Ownership & Safety
| Purpose | Fire Protection, Stock, Or Small Fish Pond |
| Owner | Mildred Cline |
| Owner Type | Private |
| Hazard Classification | Significant |
| Condition Assessment | Not assessed |
| Emergency Action Plan | Not Required |
Identifiers
| NID ID | SD01379 |
| Federal ID | SD01379 |
| More Info | State Dam Safety Program |