Ylsa Lake Dam
Ylsa Lake Dam is an earth dam located in Monroe County, Illinois, built in 1995. It carries a Significant hazard potential classification.
About Ylsa Lake Dam
The primary purpose of Ylsa Lake Dam is recreation. The dam creates a reservoir used for recreational activities such as fishing, boating, and swimming. The dam is owned by Lonnie Fulte (private). It impounds the Trib Rockhouse Creek.
The dam stands 20 feet tall and stretches 370 feet across, creates a reservoir covering 2 acres, has a maximum storage capacity of 22 acre-feet, and collects water from a drainage area of 0 square miles. Completed in 1995, the structure is 31 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 10/21/2025.
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Location
| State | Illinois |
| County | Monroe |
| Nearest City | None |
| River/Stream | Trib Rockhouse Creek |
| Coordinates | 38.28322, -90.08269 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 20 ft |
| Dam Height | 20 ft |
| Dam Length | 370 ft |
| Year Completed | 1995 (31 years old) |
Storage & Hydraulics
| NID Storage | 22 acre-ft |
| Max Storage | 22 acre-ft |
| Normal Storage | 15 acre-ft |
| Surface Area | 2 acres |
| Drainage Area | 0 sq mi |
| Max Discharge | 31 cfs |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Recreation |
| Owner | LONNIE FULTE |
| Owner Type | Private |
| Hazard Classification | Significant |
| Condition Assessment | Not Available |
| Last Inspection | 10/21/2025 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | IL50448 |
| Federal ID | IL50448 |
| More Info | State Dam Safety Program |