The six aquifer sectors of Maui island are pictured in this graphic. Maui is preparing to update its Water Use and Development Plan, a 20-year blueprint for water uses on Maui. Public hearings begin this week with a meeting on the Kahikinui, Hana and Koolau aquifer sectors Thursday evening at the Hana Community Center. Maui County graphic

A bill to fund the search for more water in West Maui has passed the Maui County Council after a state report showed some aquifers may be close to exceeding their sustainable yield.

“It’s alarming,” said Council member Keani Rawlins-Fernandez. “It was not a very optimistic report.”

On Thursday, the County Council approved spending $75,000 on the study, which comes with a $180,000 price tag. The remainder will be provided by the U.S. Geological Survey and the state Commission on Water Resource Management.

Expected to begin later this year and continue into 2026, the work includes designing and selecting a site for the test well, monitoring the site and drilling more wells to gather more information to refine the evaluation, according to the Maui County Council’s water committee.

State water commission officials say they’re noticing salinity levels in Napili and Kaanapali rising in certain instances with more pumping. Officials have also noticed less rainfall in West Maui over the last 20 years.

According to the USGS, the agency has limited information from wells inland above sea level at Launiupoko, where a study indicated groundwater levels are hundreds of feet above sea level. The agency said a deep monitor well in the Launiupoko area will help to provide more information and track changes in the freshwater lens.

“Direct information on the thickness of the freshwater lens in the area is lacking, which creates a void in understanding the current status of the groundwater resource,” a USGS study said.

According to the state Commission on Water Resource Management, the sustainable yield of the Launiupoko aquifer is 7 million gallons a day.

State officials said about 1.2 million gallons a day of groundwater is pumped daily from Launiupoko.

The availability of water remains a major issue as Lahaina residents look at ways of having a ready supply to fight future wildfires and increase the nearby affordable housing inventory. The Launiupoko aquifer system area also contains much of Lahaina town.

The federal agency said mean annual rainfall in the Launiupoko aquifer system ranges from 15 inches near the coast to greater than 360 inches above an altitude of 5,600 feet toward the summit in the east.

West Maui is comprised of six aquifers, including Honokohau, Honolulu, Honokowai, Launiupoko, Olowalu and Ukumehame.

The resident population of Maui has increased from 38,691 in 1970 to 154,100 in 2020, increasing the demand for water and groundwater withdrawals, the federal agency said.

The proposed work at Launiupoko involves looking for a place to build a monitoring well and eventually drill additional wells to collect more information and refine the existing model for groundwater, the USGS said.