Iwan #4
Key Takeaway
Iwan #4 is classified as low hazard in South Dakota. It was completed in 1957 and is 69 years old. Its primary use is fire protection.
Physical Details
| Dam Height | 29 ft (taller than 82.6% in SD) |
| Dam Length | 497 ft |
| Dam Type | Earth |
| Max Storage | 33 acre-ft |
| Normal Storage | 29 acre-ft |
| Max Discharge | 2,035 cfs |
| Year Completed | 1957 (69 years old) |
| NID ID | SD01450 |
Safety Information
No probable loss of human life and low economic/environmental losses expected.
Hazard potential describes downstream consequences of failure, not the dam's current condition. What does this mean?
Ownership
IWAN
Private
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Low Hazard 25 ftFrequently Asked Questions
What is the hazard classification of Iwan #4?
Iwan #4 is classified as Low Hazard. No probable loss of human life and low economic/environmental losses expected. This classification refers to the potential downstream consequences of a failure, not the dam's current structural condition.
Who owns and operates Iwan #4?
Iwan #4 is owned by IWAN (Private). The owner is responsible for maintenance, inspections, and compliance with dam safety regulations.
When was Iwan #4 built?
Iwan #4 was completed in 1957, making it 69 years old. Many U.S. dams were built between the 1930s and 1970s during a period of major infrastructure investment.
What is the primary purpose of Iwan #4?
Iwan #4 serves the following purposes: Fire Protection, Stock, Or Small Fish Pond, Recreation. Many dams in the U.S. are multi-purpose, supporting flood control, water supply, recreation, and other uses.
How tall is Iwan #4?
Iwan #4 has a dam height of 29 ft. Dam height is measured from the natural streambed at the downstream toe to the top of the dam, and may differ from the visible height.