Wailua Reservoir Reservoir Report

Last Updated: February 5, 2026

Wailua Reservoir, located in Wailua Homesteads, Hawaii, is a state-owned water resource that plays a crucial role in irrigation.


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Summary

Built in 1920, this Earth-type dam stands at a height of 40 feet and has a storage capacity of 1223 acre-feet. The reservoir primarily serves the purpose of irrigation, supporting agricultural activities in the region.

With a drainage area of 0.88 square miles and a maximum storage capacity of 1223 acre-feet, Wailua Reservoir is an important water source in Kauai, Hawaii. The dam has a spillway width of 144 feet and a hazard potential classified as high. Despite being assessed as in fair condition, the reservoir's risk assessment is moderate, indicating the need for ongoing monitoring and management measures to ensure its safety and functionality.

Managed by the Hawaii Department of Land and Natural Resources (DLNR), Wailua Reservoir has a history dating back over a century. The dam has undergone periodic inspections, with the most recent assessment conducted in April 2021. Climate and water resource enthusiasts will find Wailua Reservoir to be a fascinating example of infrastructure designed to support agriculture and water management in the Hawaiian landscape.

Year Completed

1920

Dam Length

1080

Dam Height

40

River Or Stream

WAILUA RIVER-N. FORK OFFSTREAM

Primary Dam Type

Earth

Hydraulic Height

30

Drainage Area

0.88

Nid Storage

1223

Structural Height

34

Hazard Potential

High

Foundations

Unlisted/Unknown

Nid Height

40
       
Seasonal Comparison

5-Day Hourly Forecast Detail

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.