Four Mile Dam

Thunder Bay· Alpena, Michigan· Built 1902· Gravity· 27 ft tall
High Hazard Hydroelectric Recreation Not Listed

Key Takeaway

Four Mile Dam is classified as high hazard in Michigan. It was completed in 1902 and is 124 years old. Its primary use is hydroelectric. 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 Height 27 ft (taller than 86.3% in MI)
Dam Length700 ft
Dam TypeGravity
Max Storage900 acre-ft
Normal Storage900 acre-ft
Surface Area90 acres
Drainage Area1,260 sq mi
Max Discharge29,000 cfs
Year Completed1902 (124 years old)
NID IDMI00170

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: August 24, 2022
State Regulated: No

Ownership

Not Listed

Nearby Dams

Frequently Asked Questions

What is the hazard classification of Four Mile Dam?

Four Mile Dam 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 Four Mile Dam?

Four Mile Dam is owned by information not available (Not Listed). The owner is responsible for maintenance, inspections, and compliance with dam safety regulations.

When was Four Mile Dam built?

Four Mile Dam was completed in 1902, making it 124 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 Four Mile Dam?

Four Mile Dam serves the following purposes: Hydroelectric, Recreation. Many dams in the U.S. are multi-purpose, supporting flood control, water supply, recreation, and other uses.

How tall is Four Mile Dam?

Four Mile Dam has a dam height of 27 ft. Dam height is measured from the natural streambed at the downstream toe to the top of the dam, and may differ from the visible height.

When was Four Mile Dam last inspected?

Four Mile Dam was last inspected on August 24, 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.