Hennepin Ash Pond 2 Dam Reservoir Report
Last Updated: December 14, 2025
Hennepin Ash Pond 2 Dam, also known as Retired Ash Pond 2, is a significant earthen dam located in Hennepin, Illinois, within Putnam County.
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Summary
Owned by the Illinois Power Company, this dam is regulated by the Illinois Department of Natural Resources and serves a primary purpose that falls under the category of 'Other'. With a height of 52 feet and a length of 3200 feet, the dam has a storage capacity of 60 acre-feet and covers a surface area of 5.4 acres.
Situated along the Illinois River, the Hennepin Ash Pond 2 Dam poses a moderate risk, as assessed on a scale of 1 to 5. The dam features uncontrolled spillways and outlets, with a maximum discharge capacity of 48 cubic feet per second. While the condition assessment is currently not available, the dam undergoes regular inspections every three years to ensure its structural integrity and overall safety. The Emergency Action Plan (EAP) for the dam was last revised in December 2018, emphasizing the importance of preparedness and risk management measures in the event of an emergency.
Known for its buttress core type and unlisted/unknown foundation, the Hennepin Ash Pond 2 Dam stands as a crucial water resource structure in Illinois. Enthusiasts interested in water resources and climate-related topics can appreciate the engineering and regulatory aspects of this dam, which plays a vital role in managing water flow and storage along the Illinois River.
Dam Length |
3200 |
Dam Height |
52 |
River Or Stream |
ILLINOIS R |
Primary Dam Type |
Earth |
Surface Area |
5.4 |
Drainage Area |
0.05 |
Nid Storage |
60 |
Outlet Gates |
Uncontrolled |
Hazard Potential |
Significant |
Foundations |
Unlisted/Unknown |
Nid Height |
52 |
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 Ash Pond 2 Dam