Simpson Lake Dam
Simpson Lake Dam is an earth dam located in Johnson County, Illinois, built in 1963. It carries a Significant hazard potential classification.
About Simpson Lake Dam
The primary purpose of Simpson Lake Dam is recreation. The dam creates a reservoir used for recreational activities such as fishing, boating, and swimming. The dam is owned by Levi Simpson (private). It impounds the Trib Bay Creek near Robbs-offstraem.
The dam stands 23 feet tall and stretches 690 feet across, and has a maximum storage capacity of 222 acre-feet. Completed in 1963, 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 06/27/2024.
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Location
| State | Illinois |
| County | Johnson |
| Nearest City | Robbs-offstraem |
| River/Stream | Trib Bay Creek |
| Coordinates | 37.46757, -88.71736 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 23 ft |
| Dam Height | 23 ft |
| Dam Length | 690 ft |
| Year Completed | 1963 (63 years old) |
Storage & Hydraulics
| NID Storage | 222 acre-ft |
| Max Storage | 222 acre-ft |
| Normal Storage | 123 acre-ft |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Recreation |
| Owner | LEVI SIMPSON |
| Owner Type | Private |
| Hazard Classification | Significant |
| Condition Assessment | Not Available |
| Last Inspection | 06/27/2024 |
| Emergency Action Plan | No |
Identifiers
| NID ID | IL00071 |
| Federal ID | IL00071 |
| More Info | State Dam Safety Program |