Coralville Milldam

IOWA RIVER· Johnson, Iowa· Built 1880· Gravity· 13 ft tall
Low Hazard Recreation Local Government

Key Takeaway

Coralville Milldam is classified as low hazard in Iowa. It was completed in 1880 and is 146 years old. Its primary use is recreation.

Physical Details

Dam Height 13 ft (taller than 3.8% in IA)
Dam Length295 ft
Dam TypeGravity
Max Storage758 acre-ft
Normal Storage599 acre-ft
Surface Area90 acres
Drainage Area3,271 sq mi
Max Discharge0 cfs
Year Completed1880 (146 years old)
NID IDIA01275

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: June 1, 1999
State Regulated: Yes
Regulatory Agency: IOWA DNR

Ownership

Johnson County Conservation Board

Local Government

Nearby Dams

Frequently Asked Questions

What is the hazard classification of Coralville Milldam?

Coralville Milldam 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 Coralville Milldam?

Coralville Milldam is owned by Johnson County Conservation Board (Local Government). The owner is responsible for maintenance, inspections, and compliance with dam safety regulations.

When was Coralville Milldam built?

Coralville Milldam was completed in 1880, making it 146 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 Coralville Milldam?

Coralville Milldam 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 Coralville Milldam?

Coralville Milldam has a dam height of 13 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 Coralville Milldam last inspected?

Coralville Milldam was last inspected on June 1, 1999. 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.