Mcnab Dam

Valley, Montana· Built 2003· Gravity·
Low Hazard Federal Government

Key Takeaway

Mcnab Dam is classified as low hazard in Montana. It was completed in 2003 and is 23 years old.

Physical Details

Dam Length396 ft
Dam TypeGravity
Max Storage172 acre-ft
Surface Area11 acres
Year Completed2003 (23 years old)
NID IDMT03893

Safety Information

Low Hazard

No probable loss of human life and low economic/environmental losses expected.

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

Emergency Action Plan: No
Last Inspection: August 18, 2016
State Regulated: No

Ownership

DOI BLM

Federal Government

Nearby Dams

Frequently Asked Questions

What is the hazard classification of Mcnab Dam?

Mcnab Dam is classified as Low Hazard. No probable loss of human life and low economic/environmental losses expected. This classification refers to the potential downstream consequences of a failure, not the dam's current structural condition.

Who owns and operates Mcnab Dam?

Mcnab Dam is owned by DOI BLM (Federal Government). The owner is responsible for maintenance, inspections, and compliance with dam safety regulations.

When was Mcnab Dam built?

Mcnab Dam was completed in 2003, making it 23 years old. Many U.S. dams were built between the 1930s and 1970s during a period of major infrastructure investment.

When was Mcnab Dam last inspected?

Mcnab Dam was last inspected on August 18, 2016. 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.