Thornapple
Key Takeaway
Thornapple is classified as low hazard in Wisconsin. It was completed in 1909 and is 117 years old. Its primary use is hydroelectric.
Physical Details
| Dam Height | 14 ft (taller than 40.1% in WI) |
| Dam Length | 530 ft |
| Dam Type | Gravity |
| Max Storage | 2.4K acre-ft |
| Normal Storage | 1.0K acre-ft |
| Surface Area | 295 acres |
| Drainage Area | 1,850 sq mi |
| Max Discharge | 19,000 cfs |
| Year Completed | 1909 (117 years old) |
| NID ID | WI00792 |
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
Northern States Power Co
Public Utility
Nearby Dams
Frequently Asked Questions
What is the hazard classification of Thornapple?
Thornapple 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 Thornapple?
Thornapple is owned by Northern States Power Co (Public Utility). The owner is responsible for maintenance, inspections, and compliance with dam safety regulations.
When was Thornapple built?
Thornapple was completed in 1909, making it 117 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 Thornapple?
Thornapple serves the following purposes: Hydroelectric, Recreation. Many dams in the U.S. are multi-purpose, supporting flood control, water supply, recreation, and other uses.
How tall is Thornapple?
Thornapple has a dam height of 14 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 Thornapple last inspected?
Thornapple was last inspected on June 7, 2022. Inspection dates indicate when a formal review occurred, not the results of that inspection.