Lake Wanalain Dam
Key Takeaway
Lake Wanalain Dam is classified as high hazard in South Dakota. It was completed in 1936 and is 90 years old. Its primary use is recreation. High hazard means loss of life is likely if the dam fails — it does not indicate the dam's current condition. Learn more.
Physical Details
| Dam Height | 21 ft (taller than 40.7% in SD) |
| Dam Length | 250 ft |
| Dam Type | Earth |
| Max Storage | 8.4K acre-ft |
| Normal Storage | 460 acre-ft |
| Surface Area | 110 acres |
| Drainage Area | 70 sq mi |
| Max Discharge | 7,467 cfs |
| Year Completed | 1936 (90 years old) |
| Year Modified | 1994 |
| NID ID | SD00716 |
Safety Information
Loss of human life is likely if the dam fails.
Hazard potential describes downstream consequences of failure, not the dam's current condition. What does this mean?
Ownership
S&PL
State Government
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Low Hazard 26 ftFrequently Asked Questions
What is the hazard classification of Lake Wanalain Dam?
Lake Wanalain Dam is classified as High Hazard. Loss of human life is likely if the dam fails. This classification refers to the potential downstream consequences of a failure, not the dam's current structural condition.
Who owns and operates Lake Wanalain Dam?
Lake Wanalain Dam is owned by S&PL (State Government). The owner is responsible for maintenance, inspections, and compliance with dam safety regulations.
When was Lake Wanalain Dam built?
Lake Wanalain Dam was completed in 1936, making it 90 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 Lake Wanalain Dam?
Lake Wanalain Dam serves the following purposes: Recreation. Many dams in the U.S. are multi-purpose, supporting flood control, water supply, recreation, and other uses.
How tall is Lake Wanalain Dam?
Lake Wanalain Dam has a dam height of 21 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.
When was Lake Wanalain Dam last inspected?
Lake Wanalain Dam was last inspected on October 3, 2022. Inspection dates indicate when a formal review occurred, not the results of that inspection.