Considerations for understanding water availability in West Maui

by Kimberly Burnett, Conrad Newfield, Christopher Wada, UHERO, January 21, 2025

This piece intends to highlight some of the inherent tradeoffs that make managing water in West Maui especially challenging. In particular, subtracting current/authorized use from “sustainable yield” as defined by the State Water Code and interpreted by CWRM may not be a reliable way to determine remaining water resources available for use. We hope summarizing what is currently understood about resource availability and potential tradeoffs associated with using these resources will help inform policy and management discussions of this challenging issue.

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Control of water resources throughout Hawai‘i, Maui County, and in particular West Maui has been at the center of political and economic power struggles since at least the mid-19th century, when surface water diversions for commercial agriculture and increased groundwater extraction reduced, or eliminated, available water for traditional crop cultivation and subsistence lifeways with collateral damage to native forests, species, and streams (Fig 1) (Scheuer & Isaki, 2021).

In June 2022, the State Commission on Water Resource Management (CWRM) designated the Lahaina Aquifer Sector Area as both a ground and surface water management area. This meant that all new and existing water uses must apply for a Water Use Permit from CWRM, which can involve a sometimes lengthy approval process by the 7-member Water Commission.

This piece intends to highlight some of the inherent tradeoffs that make managing water in this area especially challenging. In particular, subtracting current/authorized use from “sustainable yield” as defined by the State Water Code and interpreted by CWRM may not be a reliable way to determine remaining water resources available for use. This methodology fails to fully take into account the connection between surface water and groundwater, the fact that permitted/ authorized use may be counted towards sustainable yield even though is not currently being used, uncertainty regarding future land use, as well as a number of problems with the existing estimates of sustainable yield, in particular, lack of public trust protections (Burnett et al., 2020).

(We understand that CWRM is currently considering revising their estimates of sustainable yield in order to better incorporate public trust protection.)

The State Water Code (HRS Chapter 174C, 1987) defines a number of protections under the public trust doctrine to determine what is considered “reasonable and beneficial use.” The State recognizes five public trust uses of water:

(1) the exercise of traditional and customary Hawaiian rights,

(2) the maintenance of waters in their natural state,

(3) reservations of water for Hawaiian Home Lands,

(4) appurtenant rights, and

(5) domestic water use of the general public, particularly drinking water.

We hope summarizing what is currently understood about resource availability and potential tradeoffs associated with using these resources will help inform policy and management discussions of this challenging issue. 

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