John Alley
Key Takeaway
John Alley is classified as low hazard in South Dakota. It was completed in 1946 and is 80 years old. Its primary use is fire protection.
Physical Details
| Dam Height | 16 ft (taller than 15.7% in SD) |
| Dam Length | 670 ft |
| Dam Type | Earth |
| Max Storage | 128 acre-ft |
| Normal Storage | 51 acre-ft |
| Max Discharge | 4,840 cfs |
| Year Completed | 1946 (80 years old) |
| NID ID | SD00742 |
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
ROBERT ALLEY
Private
Nearby Dams
Wanblee Lake Dam
Jackson, SD
Significant Hazard 17 ftSd Noname 186
Jackson, SD
Low Hazard 16 ftSd Noname 182
Jackson, SD
Low Hazard 22 ftJacquot Dam
Bennett, SD
Significant Hazard 25 ftSd Noname 188
Jackson, SD
Low Hazard 18 ftSd Noname 135
Jackson, SD
Low Hazard 20 ftSd Noname 189
Jackson, SD
Low Hazard 13 ftFrequently Asked Questions
What is the hazard classification of John Alley?
John Alley 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 John Alley?
John Alley is owned by ROBERT ALLEY (Private). The owner is responsible for maintenance, inspections, and compliance with dam safety regulations.
When was John Alley built?
John Alley was completed in 1946, making it 80 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 John Alley?
John Alley serves the following purposes: Fire Protection, Stock, Or Small Fish Pond. Many dams in the U.S. are multi-purpose, supporting flood control, water supply, recreation, and other uses.
How tall is John Alley?
John Alley has a dam height of 16 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.