Maui Reservoir 70 Reservoir Report

Last Updated: December 20, 2025

Maui Reservoir 70, also known as Hc&S Reservoir 70, is a privately owned water storage facility located in Kahului, Maui, Hawaii.


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Summary

This reservoir, completed in 1917, serves the primary purpose of irrigation and has a normal storage capacity of 59 acre-feet, with a maximum storage capacity of 74 acre-feet. With a dam height of 16 feet and a hydraulic height of 15 feet, this earth dam structure spans a length of 1495 feet and covers a surface area of 5 acres.

Managed by the Hawaii Department of Land and Natural Resources (DLNR), Maui Reservoir 70 is regulated, inspected, and enforced by the state agency to ensure its safe operation and compliance with regulations. The reservoir poses a high hazard potential and has been assessed to be in fair condition as of the latest inspection in April 2021. Despite its moderate risk assessment, the reservoir has not undergone recent modifications or upgrades, highlighting the importance of continued monitoring and maintenance to mitigate potential risks and ensure the safety of surrounding communities.

With its historical significance and vital role in supporting irrigation activities in the region, Maui Reservoir 70 stands as a notable water resource infrastructure in Maui County. As climate change impacts water availability and management practices, maintaining the integrity and resilience of such reservoirs becomes increasingly crucial for sustainable water resource management in Hawaii.

Year Completed

1917

Dam Length

1495

Dam Height

16

River Or Stream

FED BY IRRIGATION DITCH

Primary Dam Type

Earth

Surface Area

5

Hydraulic Height

15

Drainage Area

0.01

Nid Storage

74

Structural Height

15

Hazard Potential

High

Foundations

Unlisted/Unknown

Nid Height

16
       
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.