Lake Mills

ROCK CREEK· Jefferson, Wisconsin· Built 1865· Gravity· 17 ft tall
High Hazard Recreation Local Government

Key Takeaway

Lake Mills is classified as high hazard in Wisconsin. It was completed in 1865 and is 161 years old. Its primary use is recreation. 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 17 ft (taller than 53.1% in WI)
Dam Length400 ft
Dam TypeGravity
Max Storage28.3K acre-ft
Normal Storage25.6K acre-ft
Surface Area1,371 acres
Drainage Area11 sq mi
Max Discharge115 cfs
Year Completed1865 (161 years old)
NID IDWI10222

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 5, 2021
State Regulated: Yes
Regulatory Agency: WIDNR

Ownership

City of Lake Mills

Local Government

Nearby Dams

Frequently Asked Questions

What is the hazard classification of Lake Mills?

Lake Mills 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 Lake Mills?

Lake Mills is owned by City of Lake Mills (Local Government). The owner is responsible for maintenance, inspections, and compliance with dam safety regulations.

When was Lake Mills built?

Lake Mills was completed in 1865, making it 161 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 Lake Mills?

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

How tall is Lake Mills?

Lake Mills has a dam height of 17 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 Lake Mills last inspected?

Lake Mills was last inspected on August 5, 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.