Karl Lake Dam is an earth dam located in Mercer County, Illinois, built in 1974. It carries a Significant hazard potential classification.
Dam profile
NID height · 50 ft50 ft tall and 800 ft long, taller than 92% of U.S. dams with a recorded height. Height is drawn to scale against a ten-story building, about 100 ft; the profile is a generic embankment section and the water level is illustrative.
About Karl Lake Dam
The primary purpose of Karl Lake Dam is recreation. The dam creates a reservoir used for recreational activities such as fishing, boating, and swimming. The dam is owned by Fyre Lake Property Owners Association (private). It impounds the Trib Camp Creek near Matherville.
The dam stands 50 feet tall and stretches 800 feet across, creates a reservoir covering 26 acres, has a maximum storage capacity of 550 acre-feet, and collects water from a drainage area of 0 square miles. Completed in 1974, 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. An emergency action plan is in place for this dam. The most recent inspection on record was 05/02/2025.
At 50 feet, this dam is taller than 92% of dams nationwide.
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Location
| State | Illinois |
| County | Mercer |
| Nearest City | Matherville |
| River/Stream | Trib Camp Creek |
| Coordinates | 41.31136, -90.49455 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 50 ft |
| Dam Height | 50 ft |
| Dam Length | 800 ft |
| Year Completed | 1974 (52 years old) |
Storage & Hydraulics
| NID Storage | 550 acre-ft |
| Max Storage | 550 acre-ft |
| Normal Storage | 426 acre-ft |
| Surface Area | 26 acres |
| Drainage Area | 0 sq mi |
| Max Discharge | 320 cfs |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Recreation |
| Owner | Fyre Lake Property Owners Association |
| Owner Type | Private |
| Hazard Classification | Significant |
| Condition Assessment | Not assessed |
| Last Inspection | 05/02/2025 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | IL01008 |
| Federal ID | IL01008 |
| More Info | State Dam Safety Program |