Lake Macbride Dam Reservoir Report

Last Updated: December 5, 2025

Lake Macbride Dam in Johnson County, Iowa, is a state-regulated earth dam completed in 1930 by the Corps of Engineers, with a primary purpose of recreation.


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Summary

The dam stands at a height of 56 feet and spans 900 feet, creating a reservoir with a storage capacity of 28,000 acre-feet and a surface area of 950 acres. Located on Mill Creek within Coralville Reservoir, the dam has a spillway width of 150 feet and is classified as having a significant hazard potential.

Despite its age, Lake Macbride Dam's condition assessment is regarded as satisfactory, with inspections conducted every five years to ensure its structural integrity. The dam is owned and regulated by the Iowa Department of Natural Resources, with enforcement and permitting handled at the state level. Situated in a scenic area with a drainage area of 27.1 square miles, the dam not only serves as a recreational spot but also plays a crucial role in managing water resources and mitigating flood risks in the region. For water resource and climate enthusiasts, Lake Macbride Dam is a fascinating example of engineering ingenuity and environmental stewardship in action.

Year Completed

1930

Dam Length

900

Dam Height

56

River Or Stream

MILL CREEK

Primary Dam Type

Earth

Surface Area

950

Drainage Area

27.1

Nid Storage

28000

Hazard Potential

Significant

Foundations

Rock, Soil

Nid Height

56
       
Seasonal Comparison

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Dam Data Reference

Condition Assessment

Satisfactory
No existing or potential dam safety deficiencies are recognized. Acceptable performance is expected under all loading conditions (static, hydrologic, seismic) in accordance with the minimum applicable state or federal regulatory criteria or tolerable risk guidelines.
Fair
No existing dam safety deficiencies are recognized for normal operating conditions. Rare or extreme hydrologic and/or seismic events may result in a dam safety deficiency. Risk may be in the range to take further action. Note: Rare or extreme event is defined by the regulatory agency based on their minimum
Poor A dam safety deficiency is recognized for normal operating conditions which may realistically occur. Remedial action is necessary. POOR may also be used when uncertainties exist as to critical analysis parameters which identify a potential dam safety deficiency. Investigations and studies are necessary.
Unsatisfactory
A dam safety deficiency is recognized that requires immediate or emergency remedial action for problem resolution.
Not Rated
The dam has not been inspected, is not under state or federal jurisdiction, or has been inspected but, for whatever reason, has not been rated.
Not Available
Dams for which the condition assessment is restricted to approved government users.

Hazard Potential Classification

High
Dams assigned the high hazard potential classification are those where failure or mis-operation will probably cause loss of human life.
Significant
Dams assigned the significant hazard potential classification are those dams where failure or mis-operation results in no probable loss of human life but can cause economic loss, environment damage, disruption of lifeline facilities, or impact other concerns. Significant hazard potential classification dams are often located in predominantly rural or agricultural areas but could be in areas with population and significant infrastructure.
Low
Dams assigned the low hazard potential classification are those where failure or mis-operation results in no probable loss of human life and low economic and/or environmental losses. Losses are principally limited to the owner's property.
Undetermined
Dams for which a downstream hazard potential has not been designated or is not provided.
Not Available
Dams for which the downstream hazard potential is restricted to approved government users.