Ku Tree Reservoir Reservoir Report

Last Updated: December 19, 2025

Ku Tree Reservoir, located in Wahiawa, Hawaii, is a Federal-owned water storage facility managed by the US Army.


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Summary

Built in 1925, this Earth-type dam stands at a height of 90 feet and has a storage capacity of 970 acre-feet, with a normal storage level of 880 acre-feet. The reservoir covers a surface area of 23 acres and is fed by the South Fork Kaukonahua River.

With a maximum discharge capacity of 5600 cubic feet per second, Ku Tree Reservoir plays a crucial role in water resource management in the area. The dam is regulated by the Hawaii Department of Land and Natural Resources (DLNR) and is subject to regular inspections by the US Army. The reservoir has a high hazard potential, and although the condition assessment is currently not available, the risk assessment is moderate.

Despite its age, Ku Tree Reservoir continues to serve its primary purpose efficiently, providing water storage for various uses in the region. Its strategic location in Honolulu County makes it a vital asset for water supply and flood control in the area. As a significant piece of infrastructure with historical importance, Ku Tree Reservoir stands as a testament to the enduring legacy of water resource management in Hawaii.

Year Completed

1925

Dam Length

550

Dam Height

90

River Or Stream

S Fork Kaukonahua

Primary Dam Type

Earth

Surface Area

23

Drainage Area

1

Nid Storage

970

Outlet Gates

None

Hazard Potential

High

Foundations

Unlisted/Unknown

Nid Height

90
       
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.