Lake Darling Dam Reservoir Report

Last Updated: December 6, 2025

Lake Darling Dam, located in Washington, Iowa, is a state-owned structure with a primary purpose of recreation.


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Summary

Built in 1950, this earth dam stands at a height of 47 feet and spans a length of 1230 feet, impounding the waters of Honey Creek to create Lake Darling. With a storage capacity of 9823 acre-feet and a surface area of 304 acres, the dam provides the perfect setting for outdoor enthusiasts to enjoy various recreational activities such as boating, fishing, and picnicking.

Managed by the Iowa Department of Natural Resources, Lake Darling Dam is regulated, permitted, inspected, and enforced by state authorities to ensure its safety and functionality. The dam's spillway, with a width of 385 feet, serves as an uncontrolled release point for excess water during high flow events. Despite being classified as having a significant hazard potential, the dam has been assessed as satisfactory in condition and is considered to have a moderate risk level. The last inspection in June 2020 confirmed the dam's structural integrity and its ability to withstand potential emergencies.

Surrounded by the scenic beauty of Coppock, Iowa, Lake Darling Dam offers a tranquil retreat for water resource and climate enthusiasts seeking to connect with nature. Whether exploring the surrounding wildlife or simply enjoying the peaceful ambiance of the lake, this recreational haven provides a unique opportunity to appreciate the importance of sustainable water management and environmental conservation efforts in the region.

Year Completed

1950

Dam Length

1230

Dam Height

47

River Or Stream

HONEY CREEK

Primary Dam Type

Earth

Surface Area

304

Drainage Area

19.64

Nid Storage

9823

Hazard Potential

Significant

Foundations

Rock, Soil

Nid Height

47
       
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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.