Tiskilwa Strucure 2 Dam Reservoir Report
Last Updated: December 15, 2025
Tiskilwa Structure 2 Dam, also known as Rocky Run Dam, is a critical flood risk reduction infrastructure located in Tiskilwa, Illinois.
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Summary
Built in 1960 by USDA NRCS, this earth dam stands at a height of 61 feet and spans 555 feet in length, providing essential protection to the surrounding area along the Rocky Run river. The dam has a normal storage capacity of 95 acre-feet and a maximum discharge capacity of 7185 cubic feet per second.
Managed by the local government with regulatory oversight from the Illinois Department of Natural Resources, Tiskilwa Structure 2 Dam is classified as having a high hazard potential due to its critical role in flood control. Despite its age, the dam's condition assessment is currently unavailable, and the last inspection was conducted in April 2021. While the risk assessment for the dam is moderate, with a rating of 3, there is no detailed risk management plan in place. As climate change continues to impact water resources, the maintenance and safety of structures like Tiskilwa Structure 2 Dam will be crucial in safeguarding communities from the threat of flooding.
Year Completed |
1960 |
Dam Length |
555 |
Dam Height |
61 |
River Or Stream |
ROCKY RUN |
Primary Dam Type |
Earth |
Surface Area |
13 |
Drainage Area |
3.3 |
Nid Storage |
1213 |
Outlet Gates |
Uncontrolled |
Hazard Potential |
High |
Foundations |
Unlisted/Unknown |
Nid Height |
61 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
Big Bureau Creek At Princeton
|
8cfs |
East Bureau Creek Near Bureau
|
2cfs |
Illinois River At Henry
|
3470cfs |
Indian Creek Near Wyoming
|
3cfs |
Vermilion River Near Leonore
|
17cfs |
Green River Near Geneseo
|
185cfs |
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.
Tiskilwa Strucure 2 Dam