Lake Chautauqua Upper Dam Reservoir Report

Last Updated: December 21, 2025

Located in Mason County, Illinois, the Lake Chautauqua Upper Dam is a Federal-owned structure managed by the Fish and Wildlife Service for the primary purpose of serving as a Fish and Wildlife Pond.


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Summary

Built in 1916 by the US Army Corps of Engineers, this Earth dam stands at a height of 21 feet and has a length of 15,424 feet, creating a surface area of 1,200 acres and a storage capacity of 17,280 acre-feet.

Despite its low hazard potential, the dam is currently rated as being in poor condition, with a very high risk assessment due to its age and previous modifications. The last inspection in September 2019 revealed a need for improvement, and the structure has undergone several modifications over the years to enhance its foundation, structural integrity, and hydraulic components. The dam is regulated by the Illinois Department of Natural Resources and is subject to regular inspections, permitting, and enforcement.

With a controlled spillway and a slide gate outlet, the Lake Chautauqua Upper Dam plays a crucial role in managing water flow and providing habitat for wildlife in the area. The dam's historical significance and ongoing maintenance challenges make it a focal point for water resource and climate enthusiasts interested in the intersection of infrastructure, conservation, and public safety in the region.

Years Modified

1969 - Foundation, 1969 - Structural, 1999 - Hydraulic, 1999 - Mechanical, 2003 - Structural, 2010 - Structural

Year Completed

1916

Dam Length

15424

Dam Height

17

River Or Stream

See Note

Primary Dam Type

Earth

Surface Area

1200

Hydraulic Height

17

Drainage Area

2

Nid Storage

17280

Structural Height

21

Outlet Gates

Slide (sluice gate)

Hazard Potential

Low

Foundations

Soil

Nid Height

21
       
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.