Superior 4 Dam Reservoir Report
Last Updated: December 30, 2025
Superior 4 Dam, also known as Wilsonville Lake, is a privately owned structure located in Macoupin, Illinois along the West Fork Cahokia Creek.
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Summary
Completed in 1950, this Earth dam stands at a height of 20 feet and has a storage capacity of 200 acre-feet. Despite its low hazard potential, the dam is regulated, inspected, and enforced by the Illinois Department of Natural Resources to ensure its safety and compliance with state regulations.
The primary purpose of Superior 4 Dam is classified as 'Other', with its design being of the Buttress core type. The dam features uncontrolled spillways and outlets, with no associated locks for navigation. Despite its moderate risk assessment rating, the condition assessment of the dam is currently listed as 'Not Available'. The last inspection date was in January 1988, with a scheduled inspection frequency of 5 years.
Although further details on the condition and risk management measures are not readily available, Superior 4 Dam remains an integral part of the water resource infrastructure in Illinois. Enthusiasts interested in water resource management and climate resilience will find this dam's history, design, and regulatory oversight to be of particular interest in understanding the intersection of human infrastructure with natural water systems.
Year Completed |
1950 |
Dam Height |
20 |
River Or Stream |
WEST FORK CAHOKIA CREEK |
Primary Dam Type |
Earth |
Nid Storage |
200 |
Outlet Gates |
Uncontrolled |
Hazard Potential |
Low |
Foundations |
Unlisted/Unknown |
Nid Height |
20 |
Seasonal Comparison
Weather Forecast
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.
Superior 4 Dam