Mill Creek Structure 1 Dam Reservoir Report
Last Updated: December 19, 2025
Mill Creek Structure 1 Dam, also known as Mill Creek Impoundment 1, is a private dam located in Clark County, Illinois.
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Summary
Built in 1980 by USDA NRCS, this earth dam stands at a height of 81 feet and spans 1470 feet in length. Its primary purpose is flood risk reduction, with a normal storage capacity of 17,549 acre-feet and a maximum storage of 40,300 acre-feet. The dam is situated on Mill Creek and is regulated by the Illinois Department of Natural Resources.
With a significant hazard potential and a moderate risk assessment rating, Mill Creek Structure 1 Dam plays a crucial role in managing water resources in the region. It has an uncontrolled spillway and outlet gates, with the capacity to discharge up to 39,280 cubic feet per second. The dam's location in Marshall, Illinois, makes it an important infrastructure for flood control and recreation purposes, serving the local community and surrounding areas. Regular inspections and maintenance are carried out to ensure its structural integrity and safety.
As a key component of the flood risk reduction system in the area, Mill Creek Structure 1 Dam provides valuable protection to the community against potential flooding events. Its construction and design by the Natural Resources Conservation Service reflect a commitment to sustainable water resource management and environmental stewardship. With its role in regulating water levels on Mill Creek and its contribution to the overall water infrastructure in Illinois, this dam stands as a testament to the importance of resilient and well-maintained water resources in the face of changing climates and increasing water-related challenges.
Year Completed |
1980 |
Dam Length |
1470 |
Dam Height |
81 |
River Or Stream |
MILL CREEK |
Primary Dam Type |
Earth |
Surface Area |
811 |
Drainage Area |
20.6 |
Nid Storage |
40300 |
Outlet Gates |
Uncontrolled |
Hazard Potential |
Significant |
Foundations |
Unlisted/Unknown |
Nid Height |
81 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
Wabash River At Terre Haute
|
1770cfs |
North Fork Embarras River Near Oblong
|
5cfs |
Wabash River At Riverton Ind
|
1870cfs |
Big Raccoon Creek At Coxville
|
138cfs |
Embarras River Near Camargo
|
11cfs |
Wabash River At Montezuma
|
2010cfs |
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.
Mill Creek Structure 1 Dam