Hennepin Station East Ash Pond Reservoir Report
Last Updated: December 14, 2025
Located in Putnam, Illinois, the Hennepin Station East Ash Pond is a public utility facility owned by the Illinois Power Company.
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Summary
This ash disposal facility, completed in 1996, serves as a crucial water resource management structure along the Tributary of the Illinois River. With a dam height of 26 feet and a storage capacity of 300 acre-feet, the pond covers an area of 16 acres and has a drainage area of 0.1 square miles.
Despite its low hazard potential, the Hennepin Station East Ash Pond is subject to regular state regulation, inspection, and enforcement to ensure its structural integrity and environmental impact. The facility operates under an uncontrolled spillway system, with a maximum discharge of 219 cfs. The risk assessment for this facility is moderate, with a risk management plan in place to address any potential concerns. In the event of an emergency, the facility has an Emergency Action Plan (EAP) in place, last revised in 2018, to guide response and communication protocols.
Year Completed |
1996 |
Dam Length |
3600 |
Dam Height |
26 |
River Or Stream |
TRIB ILLINOIS RIVER |
Primary Dam Type |
Earth |
Surface Area |
16 |
Drainage Area |
0.1 |
Nid Storage |
300 |
Outlet Gates |
Uncontrolled |
Hazard Potential |
Low |
Foundations |
Unlisted/Unknown |
Nid Height |
26 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
East Bureau Creek Near Bureau
|
2cfs |
Big Bureau Creek At Princeton
|
8cfs |
Illinois River At Henry
|
6710cfs |
Vermilion River Near Leonore
|
17cfs |
Fox River At Dayton
|
1040cfs |
Illinois River At Marseilles
|
4200cfs |
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.
Hennepin Station East Ash Pond