Chicago River And Harbor Controlling Works Reservoir Report
Last Updated: December 5, 2025
The Chicago River and Harbor Controlling Works, also known as the Chicago Lock, is a critical piece of infrastructure designed to reduce flood damages in downtown Chicago and maintain navigation between Lake Michigan and the Chicago Area Waterway System.
°F
°F
mph
Wind
%
Humidity
Summary
A risk assessment conducted in 2016 highlighted potential failure modes affecting the lock gates and the lock structure's condition, which could lead to a disruption of navigation and potential flooding in the city. The lock supports limited commercial tonnage but sees a high number of recreational and non-cargo commercial vessels passing through, with over 700,000 passengers transiting annually.
To manage these risks, the US Army Corps of Engineers (USACE) staff continuously operate and maintain the Chicago Lock, conducting regular inspections and collaborating with the Metropolitan Water Reclamation District (MWRD) to minimize flooding. Recent maintenance activities, such as gate replacements in 2011 and a new control building in 2007, have been implemented to improve the lock's reliability. The project also has an Emergency Action Plan (EAP) coordinated with MWRD, the City of Chicago Office of Emergency Management and Communication, and the State of Illinois, ensuring a coordinated response to high river conditions and potential emergencies. The Chicago River and Harbor Controlling Works play a vital role in both flood risk reduction and navigation in the region, safeguarding the city and its water resources.
Year Completed |
1938 |
Dam Height |
31 |
River Or Stream |
Chicago |
Primary Dam Type |
Other |
Length Of Locks |
600 |
Hydraulic Height |
9 |
Nid Storage |
1000000 |
Structural Height |
31 |
Outlet Gates |
Other Controlled - 1, Slide (sluice gate) - 8 |
Hazard Potential |
High |
Foundations |
Soil |
Nid Height |
31 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
Dam Data Reference
Condition Assessment
SatisfactoryNo 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
HighDams 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.
Chicago River And Harbor Controlling Works
Milton Lee Olive Park
Jane Addams Memorial Park
Chicago Riverwalk
River Esplanade Park
Lakeshore East Park
Montrose Harbor
South Lagoon
Des Plaines River