Wahiawa Dam Reservoir Report

Last Updated: December 19, 2025

Wahiawa Dam, also known as Lake Wilson or Wilson Reservoir, is a private-owned structure located in Waialua, Hawaii.


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Summary

Completed in 1906, this Earth dam stands at a height of 88 feet and has a structural height of 98 feet, with a length of 660 feet. It serves primarily for irrigation purposes, with a storage capacity of 9200 acre-feet and a normal storage level of 7761 acre-feet.

Situated on the Kaukonahua Stream in Honolulu County, Wahiawa Dam has a high hazard potential and is rated in poor condition. The dam features a controlled spillway with a width of 205 feet and a maximum discharge capacity of 24,500 cubic feet per second. Despite being regulated by the Hawaii Department of Land and Natural Resources, the dam's risk assessment is classified as very high, warranting close monitoring and potential risk management measures.

For water resource and climate enthusiasts, Wahiawa Dam offers a fascinating glimpse into Hawaii's water infrastructure history and the challenges of maintaining aging dams in a high-risk environment. With its critical role in irrigation and potential impact on the surrounding area in case of failure, the dam serves as a reminder of the importance of effective dam management and emergency preparedness in the face of climate change and evolving water resource needs.

Year Completed

1906

Dam Length

660

Dam Height

88

River Or Stream

KAUKONAHUA STREAM

Primary Dam Type

Earth

Surface Area

302

Hydraulic Height

88

Drainage Area

16.7

Nid Storage

9200

Structural Height

98

Hazard Potential

High

Foundations

Unlisted/Unknown

Nid Height

98
       
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.