Pinckneyville Reservoir Dam is an earth dam located in Perry County, Illinois, built in 1953. It carries a Significant hazard potential classification.
Dam profile
NID height · 45 ft45 ft tall and 920 ft long, taller than 90% 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 Pinckneyville Reservoir Dam
The primary purpose of Pinckneyville 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 Pinckneyville (local government). It impounds the Opossum Creek near Pinkneyville.
The dam stands 45 feet tall and stretches 920 feet across, creates a reservoir covering 202 acres, has a maximum storage capacity of 6,565 acre-feet, and collects water from a drainage area of 6 square miles. Completed in 1953, 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. An emergency action plan is in place for this dam. The most recent inspection on record was 12/10/2025.
At 45 feet, this dam is taller than 90% of dams nationwide.
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Location
| State | Illinois |
| County | Perry |
| Nearest City | Pinkneyville |
| River/Stream | Opossum Creek |
| Coordinates | 38.09678, -89.39685 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 45 ft |
| Dam Height | 45 ft |
| Dam Length | 920 ft |
| Year Completed | 1953 (73 years old) |
Storage & Hydraulics
| NID Storage | 6,565 acre-ft |
| Max Storage | 6,565 acre-ft |
| Normal Storage | 2,870 acre-ft |
| Surface Area | 202 acres |
| Drainage Area | 6 sq mi |
| Max Discharge | 6,371 cfs |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Water Supply |
| Owner | City of Pinckneyville |
| Owner Type | Local Government |
| Hazard Classification | Significant |
| Condition Assessment | Not assessed |
| Last Inspection | 12/10/2025 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | IL00537 |
| Federal ID | IL00537 |
| More Info | State Dam Safety Program |