Rainbow Lake Dam Reservoir Report

Last Updated: December 5, 2025

Rainbow Lake Dam, located in Hardy, Arkansas, is a privately owned structure primarily used for recreation purposes.


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Summary

Completed in 1961, this earth dam stands at a height of 42 feet and has a hydraulic height of 36 feet, with a total length of 635 feet. The dam has a normal storage capacity of 207 acre-feet and a maximum storage capacity of 310 acre-feet, serving as a popular spot for outdoor enthusiasts in the area.

Managed by the Arkansas Natural Resources Commission, Rainbow Lake Dam is subject to state regulation, inspection, and enforcement to ensure its safety and integrity. With a high hazard potential, the dam is closely monitored to mitigate any risks and protect the surrounding community. Although its condition is currently not rated, regular inspections are conducted to assess the structure's stability and address any necessary maintenance or improvements.

Despite its critical function in flood control and water supply management for the 40-Island Creek-OS river system, Rainbow Lake Dam also offers a serene and picturesque setting for recreational activities, attracting visitors to its 21-acre surface area. While the dam's spillway information and emergency preparedness details are not readily available, its historical significance and role in water resource management make it a noteworthy site for water resource and climate enthusiasts to explore and appreciate.

Year Completed

1961

Dam Length

635

Dam Height

42

River Or Stream

40-ISLAND CREEK-OS

Primary Dam Type

Earth

Surface Area

21

Hydraulic Height

36

Drainage Area

0.8

Nid Storage

310

Structural Height

42

Hazard Potential

High

Nid Height

42
       
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.