Eldorado Reservoir Dam is an earth dam located in Saline County, Illinois, built in 1920. It carries a Significant hazard potential classification.
Dam profile
NID height · 20 ft20 ft tall and 1,200 ft long. 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 Eldorado Reservoir Dam
The primary purpose of Eldorado 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 Saline Valley Conservancy District (public utility). It impounds the Trib Wolf Creek near Muddy.
The dam stands 20 feet tall and stretches 1,200 feet across, creates a reservoir covering 145 acres, has a maximum storage capacity of 1,712 acre-feet, and collects water from a drainage area of 2 square miles. Completed in 1920, the structure is over a century 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 11/08/2025.
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Location
| State | Illinois |
| County | Saline |
| Nearest City | Muddy |
| River/Stream | Trib Wolf Creek |
| Coordinates | 37.82269, -88.49466 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 20 ft |
| Dam Height | 20 ft |
| Dam Length | 1,200 ft |
| Year Completed | 1920 (106 years old) |
Storage & Hydraulics
| NID Storage | 1,712 acre-ft |
| Max Storage | 1,712 acre-ft |
| Normal Storage | 913 acre-ft |
| Surface Area | 145 acres |
| Drainage Area | 2 sq mi |
| Max Discharge | 2,778 cfs |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Water Supply |
| Owner | Saline Valley Conservancy District |
| Owner Type | Public Utility |
| Hazard Classification | Significant |
| Condition Assessment | Not assessed |
| Last Inspection | 11/08/2025 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | IL00068 |
| Federal ID | IL00068 |
| More Info | State Dam Safety Program |