Iwan No.1 is an earth dam located in Mellette County, South Dakota, built in 1973. It carries a Low hazard potential classification.
Dam profile
NID height · 28 ft28 ft tall and 300 ft long, taller than 62% 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 Iwan No.1
The primary purpose of Iwan 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 Iwan (private). It impounds the Pine Creek Offstream.
The dam stands 28 feet tall and stretches 300 feet across, and has a maximum storage capacity of 20 acre-feet. Completed in 1973, 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 | Pine Creek Offstream |
| Coordinates | 43.57666, -100.78166 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 28 ft |
| Dam Height | 28 ft |
| Dam Length | 300 ft |
| Year Completed | 1973 (53 years old) |
Storage & Hydraulics
| NID Storage | 20 acre-ft |
| Max Storage | 20 acre-ft |
| Normal Storage | 14 acre-ft |
| Max Discharge | 435 cfs |
Ownership & Safety
| Purpose | Fire Protection, Stock, Or Small Fish Pond |
| Owner | Iwan |
| Owner Type | Private |
| Hazard Classification | Low |
| Condition Assessment | Not assessed |
| Emergency Action Plan | Not Required |
Identifiers
| NID ID | SD01313 |
| Federal ID | SD01313 |
| More Info | State Dam Safety Program |