Puu Opae Reservoir Reservoir Report

Last Updated: December 19, 2025

Puu Opae Reservoir, located in Mana, Hawaii, is a state-regulated water storage facility primarily used for irrigation purposes.


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Summary

Completed in 1930, this earthen dam stands at a height of 41 feet and has a storage capacity of 295 acre-feet. With a surface area of 11.5 acres and a hydraulic height of 36 feet, the reservoir plays a crucial role in supporting agricultural activities in the region.

Despite its importance in water management, Puu Opae Reservoir has been assessed to be in poor condition, with a hazard potential rated as low. The last inspection in November 2017 highlighted the need for improvements to ensure the safety and efficiency of the structure. The reservoir's moderate risk assessment underscores the importance of continued monitoring and maintenance to mitigate potential risks and safeguard the surrounding community and environment.

As climate change impacts water resources and infrastructure, Puu Opae Reservoir serves as a vital asset in mitigating droughts and supporting local agriculture. With its historical significance and ongoing regulatory oversight by the Department of Land and Natural Resources, the reservoir represents a key piece of Hawaii's water management infrastructure. Efforts to address its current condition and enhance its resilience will be crucial in ensuring a sustainable water supply for the region's future.

Year Completed

1930

Dam Length

1000

Dam Height

41

River Or Stream

TR-NUI STREAM OFFSTREAM

Primary Dam Type

Earth

Surface Area

11.5

Hydraulic Height

36

Nid Storage

295

Structural Height

47

Hazard Potential

Low

Foundations

Unlisted/Unknown

Nid Height

47
       
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.