Lagrange Lock And Dam Reservoir Report

Last Updated: December 20, 2025

LaGrange Lock and Dam, located in Illinois on the Illinois River, serves as a crucial infrastructure for navigation purposes.


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Summary

Built in 1939 by the US Army Corps of Engineers, this concrete dam stands at a structural height of 21 feet and spans a length of 676 feet. The dam features a single lock measuring 600 feet in length and 110 feet in width, with outlet gates including Needle and Tainter types.

Despite being classified as having a significant hazard potential due to scour conditions below the dam, LaGrange Lock and Dam has undergone major rehabilitation efforts in 2020 to enhance its efficiency and reliability. The USACE continuously monitors and maintains the dam through detailed inspections, regular maintenance activities, and a robust instrumentation and monitoring program. In addition, the dam's Emergency Action Plan is regularly updated and coordinated with state and local authorities to ensure swift response in case of emergencies. With risk management measures in place and ongoing communication efforts with stakeholders and the public, LaGrange Lock and Dam remains a well-maintained and essential component of the region's water resource infrastructure.

Year Completed

1939

Dam Length

676

River Or Stream

ILLINOIS RIVER

Primary Dam Type

Concrete

Length Of Locks

600

Hydraulic Height

10

Drainage Area

25648

Nid Storage

55000

Structural Height

21

Outlet Gates

Needle - 109, Tainter (radial) - 1

Hazard Potential

Significant

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.