Sully Dam
Sully Dam is an earth dam located in Sully County, South Dakota, built in 1938. It carries a Low hazard potential classification.
About Sully Dam
The primary purpose of Sully Dam is water supply. The dam stores water for municipal, industrial, or agricultural use, helping ensure a reliable supply for the surrounding area. The dam is owned by Gf&p (state). It impounds the Okobojo.
The dam stands 22 feet tall and stretches 1,470 feet across, and has a maximum storage capacity of 2,640 acre-feet. Completed in 1938, the structure is well-established, with more than 75 years of service.
This dam has a low hazard potential classification, meaning that failure would cause minimal damage, limited primarily to the dam owner's property, with no expected loss of life. The most recent inspection on record was 10/20/2022.
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Location
| State | South Dakota |
| County | Sully |
| Nearest City | None |
| River/Stream | Okobojo |
| Coordinates | 44.70831, -100.19559 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 22 ft |
| Dam Height | 22 ft |
| Dam Length | 1,470 ft |
| Year Completed | 1938 (88 years old) |
Storage & Hydraulics
| NID Storage | 2,640 acre-ft |
| Max Storage | 2,640 acre-ft |
| Normal Storage | 1,160 acre-ft |
| Max Discharge | 9,040 cfs |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Water Supply |
| Owner | GF&P |
| Owner Type | State |
| Hazard Classification | Low |
| Last Inspection | 10/20/2022 |
| Emergency Action Plan | Not Required |
Identifiers
| NID ID | SD00434 |
| Federal ID | SD00434 |
| More Info | State Dam Safety Program |