County proposes West Maui water well

Maui County is proposing to drill an exploratory groundwater well in West Maui that officials hope will provide a potential new water source to meet future demand.

A draft environmental assessment filed last week said that the well would pump 1.44 million gallons of water per day from Honolua Aquifer. The exploratory well, attendant pump and piping, temporary silt basin and a 6-foot-high chain-link fence would be located about four miles east of Honokowai Beach Park and 3,300 feet north of the existing Mahinahina Exploratory Well.

The 0.9-acre project area is located on an abandoned pineapple field owned by Maui Land & Pineapple Co. between Kahaha Stream and Kahanaiki Gulch.

The project would cost an estimated $1.4 million.

“This (project) would add what we refer to as ‘reliable capacity,'” Maui County Water Supply Director Dave Taylor said in an email. “This is a mixture of mechanical backup for existing systems and additional supply for new users. Bottom line, it will allow us to support increased water use to meet future demand.”

If water pumped from the exploratory well meets water quality standards set by the state and federal agencies, the county may convert it into a permanent production well. Water drawn from the well would be tested for water quality and submitted to the state Department of Health. Drinking water should have a maximum contaminant (chloride) level of no more than 250 milligrams per liter, according to Environmental Protection Agency standards.

The proposed project is meant to supplement the water supply provided by the Mahina Surface Water Treatment Facility, which draws surface water from the Honokohau and Honolua streams, as well as from the Kahana Stream, according to the water department’s website. The facility services parts of Lahaina, Napili, Wahikuli and Kahana with an average of 2.4 million gallons per day.

However, during times of reduced rainfall or drought, the surface water system “has difficulty meeting the water needs in the region.”

“As surface water availability is influenced by rain, groundwater provides an inherently more reliable source,” the report said. “The proposed project . . . allows for increased system reliability so that DWS (Department of Water Supply) is able to meet the water needs of residents during those times when water availability is reduced.”

Groundwater pumped from the proposed well would also help accommodate increased demand due to future growth in the West Maui area, the report added.

Lahaina’s population has grown over the last decade and is projected to continue growing in the coming years. According to a county Department of Planning study cited in the draft report, the population in Lahaina increased by 23 percent from 2000 to 2010, from approximately 18,000 to 22,200 people. By 2020, the population for the region is projected to reach 25,100 and 29,000 by 2030.

Water systems owned by the county provide service to most of West Maui, including the coastal areas from Launiupoko to to Napili, Taylor said. Privately owned water systems are also used in a number of areas though, including parts of Kaanapali and Kapalua.

The county Department of Water Supply must complete the environmental assessment process and obtain a well construction permit and a pump installation permit from the state Commission on Water Resource Management before any construction is implemented.

Public comments may be submitted by March 25 to the Maui County Department of Water Supply at 200 S. High St., Wailuku 96793 and consultant Munekiyo & Hiraga Inc. at 305 S. High St., Suite 104, Wailuku 96793.

* Eileen Chao can be reached at