Illinois Central Reservoir Dam Reservoir Report
Last Updated: December 6, 2025
The Illinois Central Reservoir Dam, located in Jefferson County, Illinois, was completed in 1926 and serves as an important recreational resource in the region.
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Summary
Managed by a private owner, this earth dam stands at a height of 15 feet and has a length of 775 feet, providing a storage capacity of 874 acre-feet. The dam, situated on Fourmile Creek, has a spillway width of 100 feet and is classified as uncontrolled, with a significant hazard potential.
Despite its age, the dam is regularly inspected by the Illinois Department of Natural Resources (IDNR) to ensure its safety and functionality. With a moderate risk assessment rating of 3, the dam is deemed to require attention to manage potential risks effectively. The primary purpose of the Illinois Central Reservoir Dam is for recreation, offering opportunities for boating, fishing, and other water-based activities in the area. Overall, this dam plays a crucial role in providing both recreational enjoyment and flood control in Jefferson County, Illinois.
Year Completed |
1926 |
Dam Length |
775 |
Dam Height |
15 |
River Or Stream |
FOURMILE CREEK |
Primary Dam Type |
Earth |
Nid Storage |
874 |
Outlet Gates |
Uncontrolled |
Hazard Potential |
Significant |
Foundations |
Unlisted/Unknown |
Nid Height |
15 |
Seasonal Comparison
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Nearby Streamflow Levels
Dam Data Reference
Condition Assessment
SatisfactoryNo existing or potential dam safety deficiencies are recognized. Acceptable performance is expected under all loading conditions (static, hydrologic, seismic) in accordance with the minimum applicable state or federal regulatory criteria or tolerable risk guidelines.
Fair
No existing dam safety deficiencies are recognized for normal operating conditions. Rare or extreme hydrologic and/or seismic events may result in a dam safety deficiency. Risk may be in the range to take further action. Note: Rare or extreme event is defined by the regulatory agency based on their minimum
Poor A dam safety deficiency is recognized for normal operating conditions which may realistically occur. Remedial action is necessary. POOR may also be used when uncertainties exist as to critical analysis parameters which identify a potential dam safety deficiency. Investigations and studies are necessary.
Unsatisfactory
A dam safety deficiency is recognized that requires immediate or emergency remedial action for problem resolution.
Not Rated
The dam has not been inspected, is not under state or federal jurisdiction, or has been inspected but, for whatever reason, has not been rated.
Not Available
Dams for which the condition assessment is restricted to approved government users.
Hazard Potential Classification
HighDams assigned the high hazard potential classification are those where failure or mis-operation will probably cause loss of human life.
Significant
Dams assigned the significant hazard potential classification are those dams where failure or mis-operation results in no probable loss of human life but can cause economic loss, environment damage, disruption of lifeline facilities, or impact other concerns. Significant hazard potential classification dams are often located in predominantly rural or agricultural areas but could be in areas with population and significant infrastructure.
Low
Dams assigned the low hazard potential classification are those where failure or mis-operation results in no probable loss of human life and low economic and/or environmental losses. Losses are principally limited to the owner's property.
Undetermined
Dams for which a downstream hazard potential has not been designated or is not provided.
Not Available
Dams for which the downstream hazard potential is restricted to approved government users.
Illinois Central Reservoir Dam