Superior Lake Dam Reservoir Report
Last Updated: January 12, 2026
Superior Lake Dam, located in Mount Vernon, Illinois, was completed in 1953 by the Superior Oil Company and serves as a crucial water supply source in the region.
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Summary
The earth dam, with a height of 23 feet and a length of 350 feet, impounds the waters of the TRIB Big Muddy River, providing a maximum storage capacity of 729 acre-feet. The dam is regulated by the Illinois Department of Natural Resources and undergoes regular inspections to ensure its structural integrity and safety.
Despite being classified as having a low hazard potential, Superior Lake Dam is considered to have a moderate risk level, with a risk assessment rating of 3 out of 5. The dam features an uncontrolled spillway with a width of 680 feet and outlet gates that are also uncontrolled. While the condition assessment of the dam is not available, the Emergency Action Plan (EAP) was last revised in 1992, indicating a need for updated emergency procedures and guidelines. With its strategic location and importance as a water supply structure, Superior Lake Dam remains a focal point for water resource and climate enthusiasts interested in the management and regulation of vital water infrastructure in Illinois.
Year Completed |
1953 |
Dam Length |
350 |
Dam Height |
23 |
River Or Stream |
TRIB BIG MUDDY RIVER |
Primary Dam Type |
Earth |
Nid Storage |
729 |
Outlet Gates |
Uncontrolled |
Hazard Potential |
Low |
Foundations |
Unlisted/Unknown |
Nid Height |
23 |
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 Lake Dam