Marble Rock Milldam

SHELL ROCK RIVER· Floyd, Iowa· Built 1913· Gravity· 15 ft tall
Low Hazard Recreation Local Government

Key Takeaway

Marble Rock Milldam is classified as low hazard in Iowa. It was completed in 1913 and is 113 years old. Its primary use is recreation.

Physical Details

Dam Height 15 ft (taller than 4.4% in IA)
Dam Length187 ft
Dam TypeGravity
Max Storage836 acre-ft
Normal Storage836 acre-ft
Surface Area110 acres
Drainage Area1,318 sq mi
Max Discharge0 cfs
Year Completed1913 (113 years old)
NID IDIA01309

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: December 12, 1989
State Regulated: Yes
Regulatory Agency: IOWA DNR

Ownership

City of Marble Rock

Local Government

Nearby Dams

Frequently Asked Questions

What is the hazard classification of Marble Rock Milldam?

Marble Rock 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 Marble Rock Milldam?

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

When was Marble Rock Milldam built?

Marble Rock Milldam was completed in 1913, making it 113 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 Marble Rock Milldam?

Marble Rock 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 Marble Rock Milldam?

Marble Rock Milldam has a dam height of 15 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 Marble Rock Milldam last inspected?

Marble Rock Milldam was last inspected on December 12, 1989. 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.