Homeowners have been the largest collective water user in Lahaina, according to a report released this week by the state Commission on Water Resource Management.
“Single-family dwelling was the biggest category of water use in West Maui by meter type, at approximately 5.5 million gallons per day, with hotels coming in second at about 3.5 million,” said Commission Deputy Director Ciara Kahahane.
The report examines 93 existing uses for surface and groundwater as of Aug. 7, 2023. That was the day existing use permit applications were due — the day before the Maui wildfires.
Kahahane said even though there’s been some water usage changes since then, the report’s goal is to help guide future water management decisions.
Lahaina home water usage varied widely among the just over 3,500 single-family home meters. More than half of these homes used less than 500 gallons per day — below Maui County’s standard of 600 gallons a day for Maui single-family dwellings. Three-quarters of them used less than 1,000 gallons a day.
But some used way more. Kahahane said 358 single-family dwelling meters used 2,000 gallons of water or more each day.
“Many of those meters were identified by county tax records as being on parcels that were non-owner-occupied. Non-owner-occupied homes frequently use more water than owner-occupied ones," she said.
Details on the breakdown of those homes into short-term or long-term rentals or second homes are not available. The size of the parcel also impacts how much water is used.
Overall, the mean daily water use of non-owner-occupied, single-family home meters was approximately double that of owner-occupied homes.
For hotels and resorts, water usage is complicated, and dependent on factors such as which water system they use, what types of landscaping and water features they have, and whether they use potable or non-potable water for irrigation.
Many hotels in Lahaina have been using solely potable water because infrastructure for irrigation water is not available.
In Kapalua and Kāʻanapali, many hotels do have access to a separate non-potable water supply. Until infrastructure improvements make recycled water more available in West Maui, Kahanane urged hotel operators to think creatively about other water sources.
To gather this data, staff did a deep dive to find accurate information. The data is based on water meter data and water usage, but sometimes there’s not a one-to-one match between the two, Kahahane explained.
Parcel zoning, water type access, and other factors can impact the data, which doesn’t always line up in the records. Commission staff compared that information with satellite imagery for verification to get the most accurate data.
Severe water shortages
It’s no secret that there are water shortages across the island, particularly in drought-plagued West Maui. But Kahahane paints a dire picture.
“Rainfall in West Maui has been significantly below normal over the last five years, so it's going to take a lot of rain to build back a healthy reserve of groundwater,” she said. “And while we all hope for more rain, we have to prepare for the current pattern of drought in West Maui to continue.”
She said the level of chlorides in groundwater wells is rising.
“It means that the aquifer is becoming saltier, which is a bad sign for the availability of water,” Kahahane explained. “So the report contains some of these early indications that our groundwater resources are becoming stressed.”
And the bad news is not just for Maui.
“Stream flows statewide registered some of their lowest recorded levels over the last few months, with many of them hitting their lowest point in more than 100 years on record,” she said. “As of the last week, more than 99% of Hawaiʻi's lands are at or above abnormally dry conditions, and a growing percentage of those lands are in extreme drought.”
Kahahane urges water conservation.
“If every unit in West Maui that is currently hooked up to a single-family dwelling meter cut back its water use to even 1,000 gallons per day, we could save almost 2 million gallons of water in Lahaina, and that does not even count hotels, condos and apartments.”
The commission will discuss the report at its 9 a.m. meeting on Tuesday. Kahahane said that with Maui County water shortage restrictions in place for West Maui, water commission staff are working to address the need for consistent restrictions across public and private water systems as they develop a longer-term water shortage plan.
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