Oahu Reservoir 155 Reservoir Report

Last Updated: December 19, 2025

Oahu Reservoir 155, also known as Reservoir #155, is a state-owned water storage structure located in Waipahu, Honolulu, Hawaii.


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Summary

Completed in 1916, this reservoir serves primarily for irrigation purposes with a dam height of 25 feet and a length of 900 feet, providing a storage capacity of 37 acre-feet. The reservoir covers a surface area of 2.56 acres and has a maximum discharge capacity of 110 cubic feet per second.

With a high hazard potential and fair condition assessment, Oahu Reservoir 155 is regulated by the Department of Land and Natural Resources (DLNR) in Hawaii, ensuring regular inspections and enforcement measures are in place. The reservoir operates with an uncontrolled spillway type and is located within the jurisdiction of the state. Despite its moderate risk level, the reservoir plays a crucial role in supporting irrigation activities in the region, highlighting the importance of sustainable water resource management in the face of changing climate conditions.

As a key infrastructure in the water resource system of Oahu, Reservoir 155 remains a vital component in sustaining agricultural activities and ensuring water availability in the region. With ongoing monitoring and risk management measures, this reservoir exemplifies the significance of maintaining critical water structures to meet the needs of the local community while adapting to the challenges posed by climate variability and increasing water demands.

Year Completed

1916

Dam Length

900

Dam Height

25

Primary Dam Type

Earth

Surface Area

2.56

Nid Storage

37

Hazard Potential

High

Foundations

Unlisted/Unknown

Nid Height

25
       
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.