O'farrell Dam No. 1 is an earth dam located in Grant County, South Dakota, built in 2005. It carries a Low hazard potential classification.
Dam profile
NID height · 20 ft20 ft tall and 400 ft long. 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 O'farrell Dam No. 1
The primary purpose of O'farrell Dam No. 1 is fish and wildlife pond. The dam creates habitat for fish and wildlife, supporting local ecosystems and potentially serving conservation goals. The dam is owned by Marie O'farrell (private). It impounds the Tr-n. Fork Whetstone.
The dam stands 20 feet tall and stretches 400 feet across, creates a reservoir covering 7 acres, has a maximum storage capacity of 88 acre-feet, and collects water from a drainage area of 3 square miles. Completed in 2005, the structure is relatively new.
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.
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Location
| State | South Dakota |
| County | Grant |
| River/Stream | Tr-n. Fork Whetstone |
| Coordinates | 45.30601, -96.94591 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 20 ft |
| Dam Height | 20 ft |
| Dam Length | 400 ft |
| Year Completed | 2005 (21 years old) |
Storage & Hydraulics
| NID Storage | 88 acre-ft |
| Max Storage | 88 acre-ft |
| Normal Storage | 35 acre-ft |
| Surface Area | 7 acres |
| Drainage Area | 3 sq mi |
| Max Discharge | 1,070 cfs |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Fish and Wildlife Pond |
| Owner | Marie O'farrell |
| Owner Type | Private |
| Hazard Classification | Low |
| Condition Assessment | Not assessed |
| Emergency Action Plan | Not Required |
Identifiers
| NID ID | SD02586 |
| Federal ID | SD02586 |
| More Info | State Dam Safety Program |