Marion Prison Lake Dam is an earth dam located in Williamson County, Illinois, built in 1991. It carries a Significant hazard potential classification.
Dam profile
NID height · 26 ft26 ft tall and 695 ft long, taller than 55% of U.S. dams with a recorded height. 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 Marion Prison Lake Dam
The primary purpose of Marion Prison Lake 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 Federal Bureau of Prisons (federal). It impounds the Trib Limb Branch near Marion.
The dam stands 26 feet tall and stretches 695 feet across, creates a reservoir covering 37 acres, has a maximum storage capacity of 601 acre-feet, and collects water from a drainage area of 0 square miles. Completed in 1991, the structure is 35 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 07/06/2023.
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Location
| State | Illinois |
| County | Williamson |
| Nearest City | Marion |
| River/Stream | Trib Limb Branch |
| Coordinates | 37.65562, -88.97984 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 26 ft |
| Dam Height | 26 ft |
| Dam Length | 695 ft |
| Year Completed | 1991 (35 years old) |
Storage & Hydraulics
| NID Storage | 601 acre-ft |
| Max Storage | 601 acre-ft |
| Normal Storage | 270 acre-ft |
| Surface Area | 37 acres |
| Drainage Area | 0 sq mi |
| Max Discharge | 1,085 cfs |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Water Supply |
| Owner | Federal Bureau of Prisons |
| Owner Type | Federal |
| Hazard Classification | Significant |
| Condition Assessment | Not assessed |
| Last Inspection | 07/06/2023 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | IL50226 |
| Federal ID | IL50226 |
| More Info | State Dam Safety Program |