Vienna Reservoir Dam Reservoir Report

Last Updated: December 5, 2025

Located in Vienna, Illinois, the Vienna Reservoir Dam stands as a vital structure for water supply purposes in the region.


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Summary

Completed in 1968, this earth dam with a buttress core type has a height of 13 feet and a length of 2100 feet, providing a storage capacity of 55 acre-feet. The dam, situated on the tributary of Little Cache Creek, is state-regulated and inspected, ensuring its safety and functionality for the local community.

With a low hazard potential and moderate risk assessment rating, the Vienna Reservoir Dam plays a crucial role in water management and supply for the area. Despite its uncontrolled spillway and outlet gates, the dam remains a reliable source for storing water and maintaining the normal storage level of 23 acre-feet. The dam's condition assessment is currently not available, but regular inspections and a five-year inspection frequency help to ensure its continued operation and safety for the residents of Vienna and Johnson County.

As a key structure owned by the local government, the Vienna Reservoir Dam serves as a testament to the importance of water resource management in mitigating climate challenges. With its strategic location and design, this dam plays a significant role in ensuring water supply reliability and resilience in the face of changing environmental conditions.

Year Completed

1968

Dam Length

2100

Dam Height

13

River Or Stream

TRIB LITTLE CACHE CREEK

Primary Dam Type

Earth

Nid Storage

55

Outlet Gates

Uncontrolled

Hazard Potential

Low

Foundations

Unlisted/Unknown

Nid Height

13
       
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.