Eau Pleine

Big Eau Pleine River· Marathon, Wisconsin· Built 1937· Gravity· 45 ft tall
High Hazard Hydroelectric Recreation Public Utility

Key Takeaway

Eau Pleine is classified as high hazard in Wisconsin. It was completed in 1937 and is 89 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 45 ft (taller than 95.9% in WI)
Dam Length8,599 ft
Dam TypeGravity
Max Storage98.1K acre-ft
Normal Storage98.1K acre-ft
Surface Area6,677 acres
Drainage Area370 sq mi
Max Discharge20,767 cfs
Year Completed1937 (89 years old)
NID IDWI00753

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 1, 2022
State Regulated: No

Ownership

Wisconsin Valley Improvement Company

Public Utility

Nearby Dams

Frequently Asked Questions

What is the hazard classification of Eau Pleine?

Eau Pleine 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 Eau Pleine?

Eau Pleine is owned by Wisconsin Valley Improvement Company (Public Utility). The owner is responsible for maintenance, inspections, and compliance with dam safety regulations.

When was Eau Pleine built?

Eau Pleine was completed in 1937, making it 89 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 Eau Pleine?

Eau Pleine 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 Eau Pleine?

Eau Pleine has a dam height of 45 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 Eau Pleine last inspected?

Eau Pleine was last inspected on August 1, 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.