Iwan #4
Iwan #4 is an earth dam located in Mellette County, South Dakota, built in 1957. It carries a Low hazard potential classification.
About Iwan #4
The primary purpose of Iwan #4 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 Iwan (private). It impounds the Trib Big White Offstream.
The dam stands 29 feet tall and stretches 497 feet across, and has a maximum storage capacity of 33 acre-feet. Completed in 1957, the structure is well into its service life at over 50 years old.
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 | Mellette |
| Nearest City | None |
| River/Stream | Trib Big White Offstream |
| Coordinates | 43.80833, -101.08499 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 29 ft |
| Dam Height | 29 ft |
| Dam Length | 497 ft |
| Year Completed | 1957 (69 years old) |
Storage & Hydraulics
| NID Storage | 33 acre-ft |
| Max Storage | 33 acre-ft |
| Normal Storage | 29 acre-ft |
| Max Discharge | 2,035 cfs |
Ownership & Safety
| Purpose | Fire Protection, Stock, Or Small Fish Pond |
| Owner | IWAN |
| Owner Type | Private |
| Hazard Classification | Low |
| Emergency Action Plan | Not Required |
Identifiers
| NID ID | SD01450 |
| Federal ID | SD01450 |
| More Info | State Dam Safety Program |