Thomas J. O'Brien Lock and Controlling Works

CALUMET RIVER· Cook, Illinois· Built 1960· Concrete·
High Hazard Navigation Other Flood Risk Reduction Federal Government

Key Takeaway

Thomas J. O'Brien Lock and Controlling Works is classified as high hazard in Illinois. It was completed in 1960 and is 66 years old. Its primary use is navigation. High hazard means loss of life is likely if the dam fails — it does not indicate the dam's current condition. Learn more.

Physical Details

Dam Length430 ft
Dam TypeConcrete
Max Storage9.7K acre-ft
Normal Storage0 acre-ft
Surface Area0 acres
Drainage Area250 sq mi
Max Discharge2,200 cfs
Year Completed1960 (66 years old)
NID IDIL01013

Safety Information

High Hazard

Loss of human life is likely if the dam fails.

Hazard potential describes downstream consequences of failure, not the dam's current condition. What does this mean?

Emergency Action Plan: Yes
Last Inspection: April 5, 2022
State Regulated: Yes

Ownership

USACE - Chicago District

Federal Government

Nearby Dams

Frequently Asked Questions

What is the hazard classification of Thomas J. O'Brien Lock and Controlling Works?

Thomas J. O'Brien Lock and Controlling Works is classified as High Hazard. Loss of human life is likely if the dam fails. This classification refers to the potential downstream consequences of a failure, not the dam's current structural condition.

Who owns and operates Thomas J. O'Brien Lock and Controlling Works?

Thomas J. O'Brien Lock and Controlling Works is owned by USACE - Chicago District (Federal Government). The owner is responsible for maintenance, inspections, and compliance with dam safety regulations.

When was Thomas J. O'Brien Lock and Controlling Works built?

Thomas J. O'Brien Lock and Controlling Works was completed in 1960, making it 66 years old. Many U.S. dams were built between the 1930s and 1970s during a period of major infrastructure investment.

What is the primary purpose of Thomas J. O'Brien Lock and Controlling Works?

Thomas J. O'Brien Lock and Controlling Works serves the following purposes: Navigation, Other, Flood Risk Reduction. Many dams in the U.S. are multi-purpose, supporting flood control, water supply, recreation, and other uses.

When was Thomas J. O'Brien Lock and Controlling Works last inspected?

Thomas J. O'Brien Lock and Controlling Works was last inspected on April 5, 2022. Inspection dates indicate when a formal review occurred, not the results of that inspection.

Data from the National Inventory of Dams (NID) maintained by the US Army Corps of Engineers. Dam conditions may have changed since the last update. This site is not affiliated with USACE. Do not use for emergency planning — contact your local dam safety program.