Carlinville Lake II Dam is an earth dam located in Macoupin County, Illinois, built in 1981. It carries a Significant hazard potential classification.
Dam profile
NID height · 50 ft50 ft tall and 645 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 Carlinville Lake II Dam
The primary purpose of Carlinville Lake II Dam is water supply. The dam stores water for municipal, industrial, or agricultural use, helping ensure a reliable supply for the surrounding area. The dam is owned by City of Carlinville (local government). It impounds the Trib Honey Creek near Carlinville.
The dam stands 50 feet tall and stretches 645 feet across, and has a maximum storage capacity of 3,400 acre-feet. Completed in 1981, the structure is 45 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 03/24/2026.
At 50 feet, this dam is taller than 92% of dams nationwide.
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Location
| State | Illinois |
| County | Macoupin |
| Nearest City | Carlinville |
| River/Stream | Trib Honey Creek |
| Coordinates | 39.22631, -89.83606 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 50 ft |
| Dam Height | 50 ft |
| Dam Length | 645 ft |
| Year Completed | 1981 (45 years old) |
Storage & Hydraulics
| NID Storage | 3,400 acre-ft |
| Max Storage | 3,400 acre-ft |
| Normal Storage | 1,785 acre-ft |
| Max Discharge | 3,055 cfs |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Water Supply |
| Owner | City of Carlinville |
| Owner Type | Local Government |
| Hazard Classification | Significant |
| Condition Assessment | Not assessed |
| Last Inspection | 03/24/2026 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | IL50030 |
| Federal ID | IL50030 |
| More Info | State Dam Safety Program |