Lagg Lake 1 Dam is an earth dam located in Jefferson County, Illinois, built in 1976. It carries a Low hazard potential classification.
Dam profile
NID height · 18 ft18 ft tall and 330 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 Lagg Lake 1 Dam
The primary purpose of Lagg Lake 1 Dam is recreation. The dam creates a reservoir used for recreational activities such as fishing, boating, and swimming. The dam is owned by Michel (private). It impounds the Trib Casey Creek near Idlewood.
The dam stands 18 feet tall and stretches 330 feet across, and has a maximum storage capacity of 88 acre-feet. Completed in 1976, the structure is 50 years old.
This dam has a low hazard potential classification, meaning that failure would cause minimal damage, limited primarily to the dam owner's property, with no expected loss of life. The most recent inspection on record was 06/02/2025.
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Location
| State | Illinois |
| County | Jefferson |
| Nearest City | Idlewood |
| River/Stream | Trib Casey Creek |
| Coordinates | 38.41771, -88.89065 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 18 ft |
| Dam Height | 18 ft |
| Dam Length | 330 ft |
| Year Completed | 1976 (50 years old) |
Storage & Hydraulics
| NID Storage | 88 acre-ft |
| Max Storage | 88 acre-ft |
| Normal Storage | 50 acre-ft |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Recreation |
| Owner | Michel |
| Owner Type | Private |
| Hazard Classification | Low |
| Condition Assessment | Not assessed |
| Last Inspection | 06/02/2025 |
| Emergency Action Plan | No |
Identifiers
| NID ID | IL00947 |
| Federal ID | IL00947 |
| More Info | State Dam Safety Program |