Arrowhead Lake Dam
Arrowhead Lake Dam is an earth dam located in Williamson County, Illinois, built in 1963. It carries a Significant hazard potential classification.
About Arrowhead Lake Dam
The primary purpose of Arrowhead Lake Dam is recreation. The dam creates a reservoir used for recreational activities such as fishing, boating, and swimming. The dam is owned by City Of Johnston City (private). It impounds the Trib Lake Creek near Johnston City.
The dam stands 16 feet tall and stretches 840 feet across, creates a reservoir covering 39 acres, and has a maximum storage capacity of 355 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 10/18/2023.
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Location
| State | Illinois |
| County | Williamson |
| Nearest City | Johnston City |
| River/Stream | Trib Lake Creek |
| Coordinates | 37.82706, -88.90764 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 16 ft |
| Dam Height | 16 ft |
| Dam Length | 840 ft |
| Year Completed | 1963 (63 years old) |
Storage & Hydraulics
| NID Storage | 355 acre-ft |
| Max Storage | 355 acre-ft |
| Normal Storage | 162 acre-ft |
| Surface Area | 39 acres |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Recreation |
| Owner | CITY OF JOHNSTON CITY |
| Owner Type | Private |
| Hazard Classification | Significant |
| Condition Assessment | Not Available |
| Last Inspection | 10/18/2023 |
| Emergency Action Plan | No |
Identifiers
| NID ID | IL00087 |
| Federal ID | IL00087 |
| More Info | State Dam Safety Program |