Old Plank Park Basin Dam Reservoir Report

Last Updated: December 5, 2025

Old Plank Park Basin Dam, located in Naperville, Illinois, along the Steeple Run river, serves as a crucial flood risk reduction structure in DuPage County.


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Summary

Designed by CBBEL, this concrete dam stands at a height of 10 feet and stretches across 350 feet, providing a storage capacity of 75 acre-feet. With a normal storage capacity of 39 acre-feet and a drainage area of 1.5 square miles, the dam plays a vital role in mitigating flood risks in the area.

Managed by the local government and regulated by the Illinois Department of Natural Resources, the Old Plank Park Basin Dam boasts a low hazard potential and undergoes inspections every 5 years to ensure its structural integrity and functionality. The dam features an uncontrolled spillway with a width of 191 feet, allowing for a maximum discharge of 870 cubic feet per second. While the risk assessment for the dam is moderate, measures are in place to manage any potential risks and ensure the safety of the surrounding community.

Overall, Old Plank Park Basin Dam stands as a testament to effective flood risk reduction infrastructure in Illinois, providing essential protection against potential inundation events along the Steeple Run river. With its sturdy design, regulated maintenance, and low hazard potential, this concrete dam serves as a vital asset in safeguarding the local area from the impacts of extreme weather events and climate variability.

Dam Length

350

Dam Height

10

River Or Stream

STEEPLE RUN

Primary Dam Type

Concrete

Surface Area

11

Drainage Area

1.5

Nid Storage

75

Outlet Gates

Uncontrolled

Hazard Potential

Low

Foundations

Soil

Nid Height

10
       
Seasonal Comparison

Weather Forecast

Dam Data Reference

Condition Assessment

Satisfactory
No 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

High
Dams 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.