Carlson Lake Dam is an earth dam located in Jersey County, Illinois, built in 1970. It carries a Low hazard potential classification.
Dam profile
NID height · 47 ft47 ft tall and 295 ft long, taller than 91% 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 Carlson Lake Dam
The primary purpose of Carlson Lake Dam is recreation. The dam creates a reservoir used for recreational activities such as fishing, boating, and swimming. The dam is owned by Dr. R. Carlson (private). It impounds the Trib Piasa Creek near Alton.
The dam stands 47 feet tall and stretches 295 feet across, and has a maximum storage capacity of 103 acre-feet. Completed in 1970, the structure is well into its service life at over 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 08/27/2025.
At 47 feet, this dam is taller than 91% of dams nationwide.
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Location
| State | Illinois |
| County | Jersey |
| Nearest City | Alton |
| River/Stream | Trib Piasa Creek |
| Coordinates | 39.04465, -90.20717 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 47 ft |
| Dam Height | 47 ft |
| Dam Length | 295 ft |
| Year Completed | 1970 (56 years old) |
Storage & Hydraulics
| NID Storage | 103 acre-ft |
| Max Storage | 103 acre-ft |
| Normal Storage | 93 acre-ft |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Recreation |
| Owner | Dr. R. Carlson |
| Owner Type | Private |
| Hazard Classification | Low |
| Condition Assessment | Not assessed |
| Last Inspection | 08/27/2025 |
| Emergency Action Plan | No |
Identifiers
| NID ID | IL01055 |
| Federal ID | IL01055 |
| More Info | State Dam Safety Program |