Marion Reservoir Dam is an earth dam located in Williamson County, Illinois, built in 1971. It carries a Significant hazard potential classification.
Dam profile
NID height · 25 ft25 ft tall and 895 ft long, taller than 50% 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 Reservoir Dam
The primary purpose of Marion Reservoir 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 Marion (local government). It impounds the Limb Branch near Marion.
The dam stands 25 feet tall and stretches 895 feet across, has a maximum storage capacity of 1,931 acre-feet, and collects water from a drainage area of 24 square miles. Completed in 1971, the structure is well into its service life at over 50 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. The most recent inspection on record was 06/28/2023.
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Location
| State | Illinois |
| County | Williamson |
| Nearest City | Marion |
| River/Stream | Limb Branch |
| Coordinates | 37.68351, -88.95278 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 25 ft |
| Dam Height | 25 ft |
| Dam Length | 895 ft |
| Year Completed | 1971 (55 years old) |
Storage & Hydraulics
| NID Storage | 1,931 acre-ft |
| Max Storage | 1,931 acre-ft |
| Normal Storage | 966 acre-ft |
| Drainage Area | 24 sq mi |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Water Supply |
| Owner | City of Marion |
| Owner Type | Local Government |
| Hazard Classification | Significant |
| Condition Assessment | Not assessed |
| Last Inspection | 06/28/2023 |
| Emergency Action Plan | No |
Identifiers
| NID ID | IL00014 |
| Federal ID | IL00014 |
| More Info | State Dam Safety Program |