Rocky Run Lake Dam
Rocky Run Lake Dam is an earth dam located in Hancock County, Illinois, built in 1971. It carries a Significant hazard potential classification.
About Rocky Run Lake Dam
The primary purpose of Rocky Run Lake Dam is flood risk reduction. The dam is designed to control downstream flooding by temporarily storing excess water during storms and releasing it at a controlled rate. The dam is owned by Hunt-lima Drainage District (local government). It impounds the Rocky Run Creek near Tioga.
The dam stands 69 feet tall and stretches 596 feet across, and has a maximum storage capacity of 520 acre-feet. Completed in 1971, the structure is well into its service life at over 50 years old.
This dam has a significant hazard potential classification, meaning that a failure could cause significant economic damage — flooding roads, bridges, or property downstream — but is not expected to result in loss of life. The most recent inspection on record was 04/08/2024.
At 69 feet, this dam is taller than 96% of all dams in the United States.
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Location
| State | Illinois |
| County | Hancock |
| Nearest City | Tioga |
| River/Stream | Rocky Run Creek |
| Coordinates | 40.26793, -91.41762 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 69 ft |
| Dam Height | 69 ft |
| Dam Length | 596 ft |
| Year Completed | 1971 (55 years old) |
Storage & Hydraulics
| NID Storage | 520 acre-ft |
| Max Storage | 520 acre-ft |
| Normal Storage | 164 acre-ft |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Flood Risk Reduction |
| Owner | HUNT-LIMA DRAINAGE DISTRICT |
| Owner Type | Local Government |
| Hazard Classification | Significant |
| Condition Assessment | Not Available |
| Last Inspection | 04/08/2024 |
| Emergency Action Plan | No |
Identifiers
| NID ID | IL00111 |
| Federal ID | IL00111 |
| More Info | State Dam Safety Program |