New Gillespie Lake Dam Reservoir Report
Last Updated: December 23, 2025
New Gillespie Lake Dam, located in Macoupin, Illinois, is a crucial water supply structure owned by the local government.
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Summary
Constructed in 1956 by the Caldwell-Rhoads Co., this earth-filled dam stands at a height of 41 feet and spans 868 feet along the Dry Fork Macoupin Creek. With a storage capacity of 4,975 acre-feet and a surface area of 216 acres, it plays a vital role in managing water resources in the region.
This dam is regulated by the Illinois Department of Natural Resources and undergoes regular inspections to ensure its safety and functionality. With a significant hazard potential and moderate risk assessment, the dam is equipped with an uncontrolled spillway and outlet gates. Despite not having a condition assessment available, the dam's emergency action plan status and risk management measures are currently undisclosed.
As a key component in the water supply infrastructure of Macoupin Station, New Gillespie Lake Dam serves as a critical resource for the community. Its efficient operation and maintenance are essential for ensuring water security and mitigating potential risks associated with its significant hazard potential.
Year Completed |
1956 |
Dam Length |
868 |
Dam Height |
41 |
River Or Stream |
DRY FORK MACOUPIN CREEK |
Primary Dam Type |
Earth |
Surface Area |
216 |
Drainage Area |
12.3 |
Nid Storage |
4975 |
Outlet Gates |
Uncontrolled |
Hazard Potential |
Significant |
Foundations |
Unlisted/Unknown |
Nid Height |
41 |
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.
New Gillespie Lake Dam