Maui Reservoir 74 Reservoir Report

Last Updated: December 20, 2025

Maui Reservoir 74, also known as Hc&S Reservoir 74 or Waiale Reservoir No.2, is a privately owned reservoir located in Kahului, Maui, Hawaii.


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Summary

Built in 1916 for irrigation purposes, this Earth-type dam stands at a height of 25 feet and has a storage capacity of 248 acre-feet. With a surface area of 19.2 acres and a drainage area of 1.11 square miles, this reservoir plays a crucial role in agricultural water supply in the region.

Despite its age and historical significance, Maui Reservoir 74 is facing some challenges in terms of its condition and hazard potential. The dam has been assessed as being in poor condition, with a high hazard potential, and a moderate risk level. Its last inspection in May 2019 revealed the need for improvements, and the emergency action plan (EAP) readiness is unclear. It is monitored by the Hawaii Department of Land and Natural Resources (DLNR) and undergoes inspections every five years to ensure its safety and functionality.

As a key water resource infrastructure in Maui, the maintenance and upkeep of Maui Reservoir 74 are crucial in ensuring a reliable water supply for irrigation purposes. With its historical significance and important role in agricultural activities, it is essential that the necessary risk management measures and maintenance efforts are put in place to safeguard this reservoir for the future.

Year Completed

1916

Dam Length

130

Dam Height

25

River Or Stream

IAO & WAIHEE STREAM OFFSTREAM

Primary Dam Type

Earth

Surface Area

19.2

Hydraulic Height

22

Drainage Area

1.11

Nid Storage

248

Structural Height

28

Hazard Potential

High

Foundations

Unlisted/Unknown

Nid Height

28
       
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.