Aii Reservoir Reservoir Report

Last Updated: February 5, 2026

Aii Reservoir in Kapaia, Hawaii is a privately owned water storage facility primarily used for irrigation purposes.


Summary

Completed in 1920, this Earth-type dam stands at 21 feet high and has a storage capacity of 68 acre-feet. Situated along the TR-HANAMAULU STREAM OFFSTREAM, the reservoir covers a surface area of 5.2 acres and serves as a vital water resource in the region.

Managed by the DLNR and regulated by the state of Hawaii, Aii Reservoir is inspected regularly for safety and maintenance. With a high hazard potential and fair condition assessment, the reservoir poses a moderate risk and is subject to emergency preparedness protocols. The spillway, with a width of 40 feet, is uncontrolled, adding to the reservoir's unique design and operational features.

Climate and water resource enthusiasts will find Aii Reservoir an intriguing structure, showcasing the intersection of human engineering with natural water systems. From its historical significance to its current role in irrigation, this reservoir in Kauai, Hawaii exemplifies the importance of sustainable water management practices in the face of climate change challenges.



°F

°F

mph

Wind

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Humidity


15-Day Weather Outlook


Year Completed

1920

Dam Length

350

Dam Height

21

River Or Stream

TR-HANAMAULU STREAM OFFSTREAM

Primary Dam Type

Earth

Surface Area

5.2

Hydraulic Height

20

Drainage Area

0.21

Nid Storage

68

Structural Height

26

Hazard Potential

High

Foundations

Unlisted/Unknown

Nid Height

26
       
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.