Arnold Dam Reservoir Report

Last Updated: December 8, 2025

Arnold Dam, located in Rathbun Reservoir, Iowa, is a privately owned structure designed by the Soil Conservation Service (SCS) for fire protection, stock, and small fish pond purposes.


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Summary

Completed in 1984, the earth dam stands at a height of 28 feet and stretches 550 feet in length. With a storage capacity of 115 acre-feet, the dam serves a drainage area of 0.23 square miles and covers a surface area of 8.3 acres.

Managed by the Iowa Department of Natural Resources, Arnold Dam is regulated, permitted, inspected, and enforced by state authorities to ensure its safety and functionality. Despite its low hazard potential and moderate risk assessment, the dam's condition is currently not rated, highlighting the need for ongoing monitoring and maintenance. The dam's primary purpose, coupled with its controlled spillway and uncontrolled spillway type, underscores its importance in safeguarding the surrounding area from potential flooding and water resource management.

In the picturesque setting of Lucas County, Iowa, Arnold Dam stands as a vital component of the local ecosystem and community. As water resource and climate enthusiasts delve into the intricacies of this structure, its role in fire protection, stock maintenance, and ecological preservation becomes increasingly apparent. With a history dating back to the 1980s, the dam continues to serve its intended purposes while emphasizing the importance of sustainable water management practices in the region.

Year Completed

1984

Dam Length

550

Dam Height

28

River Or Stream

TR- LOST BRANCH

Primary Dam Type

Earth

Surface Area

8.3

Drainage Area

0.23

Nid Storage

115

Hazard Potential

Low

Foundations

Soil

Nid Height

28
       
Seasonal Comparison

Weather Forecast

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.