Dresden Island Lock And Dam Reservoir Report

Last Updated: December 5, 2025

Dresden Island Lock and Dam, located in Morris, Illinois, along the Illinois River, was completed in 1933 by the US Army Corps of Engineers for the primary purpose of navigation.


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Summary

This concrete dam with a hydraulic height of 22 feet and a structural height of 33 feet plays a crucial role in managing water levels and maintaining structural integrity along the river. With a spillway width of 966 feet and a controlled spillway type, the dam has a significant hazard potential and a very high risk assessment rating.

The dam, with a length of 1750 feet and a storage capacity of 12,000 acre-feet, faces the challenges of flood risk associated with severe weather events and inconsistent water inflows. To address these risks, the US Army Corps of Engineers continually monitors the dam's condition, prioritizes risk-reducing activities, and collaborates with local emergency managers to raise awareness and prepare for potential dam-related emergencies. Regular maintenance and updates to the emergency action plan are essential components of the risk management measures in place for Dresden Island Lock and Dam.

As a critical infrastructure for water resource management and climate resilience, Dresden Island Lock and Dam showcases the importance of proactive risk management and collaboration between federal agencies and local stakeholders. With its historical significance and ongoing efforts to address flood risks, the dam serves as a vital component of the water infrastructure in Grundy County, Illinois, protecting communities along the Illinois River and ensuring safe navigation for waterway users.

Year Completed

1933

Dam Length

1750

River Or Stream

ILLINOIS RIVER

Primary Dam Type

Concrete

Surface Area

2180

Length Of Locks

600

Hydraulic Height

22

Drainage Area

7278

Nid Storage

12000

Structural Height

33

Outlet Gates

Tainter (radial) - 9, Uncontrolled - 0

Hazard Potential

Significant

Foundations

Rock

Nid Height

33
       
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.