Mississippi River Lock and Dam 20

MISSISSIPPI RIVER· Adams, Missouri· Built 1936· Concrete·
Significant Hazard Navigation Federal Government

Key Takeaway

Mississippi River Lock and Dam 20 is classified as significant hazard in Missouri. It was completed in 1936 and is 90 years old. Its primary use is navigation. Significant hazard means failure could cause economic or environmental damage. Learn more.

Physical Details

Dam Length2,604 ft
Dam TypeConcrete
Max Storage58.0K acre-ft
Normal Storage0 acre-ft
Surface Area7,542 acres
Drainage Area134,300 sq mi
Max Discharge510,000 cfs
Year Completed1936 (90 years old)
NID IDMO10303

Safety Information

Significant Hazard

No probable loss of human life, but can cause economic loss, environmental damage, or disruption of lifeline facilities.

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

Emergency Action Plan: Yes
Last Inspection: June 15, 2021
State Regulated: No

Ownership

USACE - Rock Island District

Federal Government

Nearby Dams

Frequently Asked Questions

What is the hazard classification of Mississippi River Lock and Dam 20?

Mississippi River Lock and Dam 20 is classified as Significant Hazard. No probable loss of human life, but can cause economic loss, environmental damage, or disruption of lifeline facilities. This classification refers to the potential downstream consequences of a failure, not the dam's current structural condition.

Who owns and operates Mississippi River Lock and Dam 20?

Mississippi River Lock and Dam 20 is owned by USACE - Rock Island District (Federal Government). The owner is responsible for maintenance, inspections, and compliance with dam safety regulations.

When was Mississippi River Lock and Dam 20 built?

Mississippi River Lock and Dam 20 was completed in 1936, making it 90 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 Mississippi River Lock and Dam 20?

Mississippi River Lock and Dam 20 serves the following purposes: Navigation. Many dams in the U.S. are multi-purpose, supporting flood control, water supply, recreation, and other uses.

When was Mississippi River Lock and Dam 20 last inspected?

Mississippi River Lock and Dam 20 was last inspected on June 15, 2021. 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.