Diamond Lake Dam Reservoir Report

Last Updated: December 7, 2025

Diamond Lake Dam, located in Dickinson County, Iowa, is a state-owned structure completed in 1957 primarily for recreational purposes.


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Summary

The dam, an earth type with a height of 8 feet and a length of 400 feet, impounds the waters of the Little Sioux River to create Diamond Lake. With a storage capacity of 1800 acre-feet, the dam serves as a popular destination for water enthusiasts and outdoor enthusiasts alike.

The dam is regulated by the Iowa Department of Natural Resources and is inspected, permitted, and enforced by state agencies to ensure its safety and compliance with regulations. Despite its low hazard potential and moderate risk assessment, the dam's condition assessment is currently not rated. The dam has an uncontrolled spillway type and a surface area of 129 acres, providing ample space for recreational activities such as boating, fishing, and wildlife watching.

While Diamond Lake Dam may not be the largest or most complex structure, its importance lies in providing a safe and enjoyable environment for visitors to engage with nature and water resources. As climate and water resource enthusiasts, understanding the management and maintenance of dams like Diamond Lake Dam is crucial to ensuring the sustainability and resilience of our water infrastructure in the face of changing environmental conditions.

Year Completed

1957

Dam Length

400

Dam Height

8

River Or Stream

TR- LITTLE SIOUX RIVER

Primary Dam Type

Earth

Surface Area

129

Drainage Area

2.84

Nid Storage

1800

Hazard Potential

Low

Foundations

Soil

Nid Height

8
       
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.