Timber Lake Dam is an earth dam located in St. Clair County, Illinois. It carries a Significant hazard potential classification.
Dam profile
NID height · 20 ft20 ft tall and 100 ft long. Height is drawn to scale against a two-story house, about 25 ft; the profile is a generic embankment section and the water level is illustrative.
About Timber Lake Dam
The primary purpose of Timber 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 Ray, Dollus & Manning (private). It impounds the Trib Wolf Branch near Swansea.
The dam stands 20 feet tall and stretches 100 feet across, creates a reservoir covering 20 acres, and has a maximum storage capacity of 35 acre-feet.
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 10/17/2022.
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Location
| State | Illinois |
| County | St. Clair |
| Nearest City | Swansea |
| River/Stream | Trib Wolf Branch |
| Coordinates | 38.55994, -89.98516 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 20 ft |
| Dam Height | 20 ft |
| Dam Length | 100 ft |
Storage & Hydraulics
| NID Storage | 35 acre-ft |
| Max Storage | 35 acre-ft |
| Normal Storage | 25 acre-ft |
| Surface Area | 20 acres |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Flood Risk Reduction |
| Owner | Ray, Dollus & Manning |
| Owner Type | Private |
| Hazard Classification | Significant |
| Condition Assessment | Not assessed |
| Last Inspection | 10/17/2022 |
| Emergency Action Plan | No |
Identifiers
| NID ID | IL50598 |
| Federal ID | IL50598 |
| More Info | State Dam Safety Program |