Wonder Lake Dam
Key Takeaway
Wonder Lake Dam is classified as high hazard in Illinois. It was completed in 1929 and is 97 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 | 27 ft (taller than 51.5% in IL) |
| Dam Length | 1,050 ft |
| Dam Type | Earth |
| Max Storage | 10.2K acre-ft |
| Normal Storage | 4.9K acre-ft |
| Surface Area | 728 acres |
| Drainage Area | 97 sq mi |
| Max Discharge | 8,471 cfs |
| Year Completed | 1929 (97 years old) |
| NID ID | IL00585 |
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
MASTER PROPERTY OWNERS ASSOCIATION, INC.
Private
Nearby Dams
Wonder Lake Sediment Dewatering Facility Dam
McHenry, IL
High Hazard 22 ftWold Lake Dam
McHenry, IL
Low Hazard 11 ftKazimer Lake Dam
McHenry, IL
Significant Hazard 15 ftStratton Lock and Dam
McHenry, IL
Significant Hazard 7 ftBlack Tern Marsh Dam
McHenry, IL
Low Hazard 7 ftYellow Head Marsh Dam
McHenry, IL
Low Hazard 7 ftThunderbird Lake 1 Dam
McHenry, IL
Low Hazard 7 ftThunderbird Lake 2 Dam
McHenry, IL
Low Hazard 10 ftFrequently Asked Questions
What is the hazard classification of Wonder Lake Dam?
Wonder Lake 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 Wonder Lake Dam?
Wonder Lake Dam is owned by MASTER PROPERTY OWNERS ASSOCIATION, INC. (Private). The owner is responsible for maintenance, inspections, and compliance with dam safety regulations.
When was Wonder Lake Dam built?
Wonder Lake Dam was completed in 1929, making it 97 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 Wonder Lake Dam?
Wonder Lake 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 Wonder Lake Dam?
Wonder Lake Dam has a dam height of 27 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 Wonder Lake Dam last inspected?
Wonder Lake Dam was last inspected on October 18, 2019. Inspection dates indicate when a formal review occurred, not the results of that inspection.