Lake Henry Dam Reservoir Report

Last Updated: December 5, 2025

Lake Henry Dam, located in Murphysboro, Illinois, is a privately owned structure designed by Mitchell-Nack with a primary purpose of recreation.


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Summary

Completed in 1963, this earth dam stands at a height of 13 feet and spans 290 feet in length, creating a reservoir with a storage capacity of 78 acre-feet. Situated on the TRIB Big Muddy River, the dam is regulated and inspected by the Illinois Department of Natural Resources, ensuring its safety and compliance with state standards.

Despite its low hazard potential, Lake Henry Dam has a moderate risk assessment rating of 3, prompting the need for ongoing risk management measures. The dam features an uncontrolled spillway with a width of 25 feet and outlet gates that are also uncontrolled. While the condition assessment of the dam is not currently available, it undergoes inspections every 5 years to maintain its structural integrity and operational efficiency. The dam's emergency action plan status, inundation maps, and risk characterization are areas that may require further attention to enhance overall safety and preparedness.

Water resource and climate enthusiasts will appreciate the unique characteristics of Lake Henry Dam, not only as a recreational spot but also as a vital infrastructure contributing to water management in the region. With its historical significance dating back to the 1960s, the dam serves as a reminder of the importance of proper maintenance and risk assessment in safeguarding water resources and infrastructure against potential hazards. As efforts continue to monitor and improve the dam's safety measures, Lake Henry Dam remains a valuable asset for both recreational enjoyment and environmental conservation in Illinois' Jackson County.

Year Completed

1963

Dam Length

290

Dam Height

13

River Or Stream

TRIB BIG MUDDY RIVER

Primary Dam Type

Earth

Nid Storage

78

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.