T. Mahaffey is an earth dam located in Meade County, South Dakota, built in 1948. It carries a Low hazard potential classification.
Dam profile
NID height · 26 ft26 ft tall and 550 ft long, taller than 55% 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 T. Mahaffey
The primary purpose of T. Mahaffey is irrigation. The dam stores and diverts water for agricultural irrigation, supporting farming operations in the surrounding area. The dam is owned by Theodore Mahaffey (private). It impounds the Tr Cheyenne.
The dam stands 26 feet tall and stretches 550 feet across, creates a reservoir covering 14 acres, has a maximum storage capacity of 126 acre-feet, and collects water from a drainage area of 1 square miles. Completed in 1948, 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 11/08/1985. That was over 40 years ago.
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Location
| State | South Dakota |
| County | Meade |
| Nearest City | None |
| River/Stream | Tr Cheyenne |
| Coordinates | 44.75333, -102.20332 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 26 ft |
| Dam Height | 26 ft |
| Dam Length | 550 ft |
| Year Completed | 1948 (78 years old) |
Storage & Hydraulics
| NID Storage | 126 acre-ft |
| Max Storage | 126 acre-ft |
| Normal Storage | 93 acre-ft |
| Surface Area | 14 acres |
| Drainage Area | 1 sq mi |
| Max Discharge | 657 cfs |
Ownership & Safety
| Purpose | Irrigation |
| Owner | Theodore Mahaffey |
| Owner Type | Private |
| Hazard Classification | Low |
| Condition Assessment | Not assessed |
| Last Inspection | 11/08/1985 |
| Emergency Action Plan | Not Required |
Identifiers
| NID ID | SD00395 |
| Federal ID | SD00395 |
| More Info | State Dam Safety Program |