TRACE LEVELS OF SELENIUM DETECTED IN LAHAINA WATER SYSTEM

HONOLULU - Trace levels of selenium have been detected for the first time in water samples collected from the County of Maui Department of Water Supply's Lahaina water system (Public Water System HI0000214), which serves the Lahaina and Napili-Honokōwai areas on the island of Maui.

The detections of selenium are below the U.S. Environmental Protection Agency (EPA) and Hawaiʻi Department of Health (DOH) Maximum Contaminant Level (MCL) and are unlikely to pose a public health risk.

Selenium was detected in samples collected at the Napili A, B, C, and Honokohua A, B Chlorinator on Sept. 29, and Oct. 23, 2025. The Maui Department of Water Supply notified DOH of the initial detection through an email on Nov. 5, 2025. The detected selenium levels ranged from 6 to 7.4 micrograms per liter (ug/L), which are below the EPA and DOH MCL for selenium of 50 ug/L. MCLs are the highest levels of contaminants that are allowed in drinking water by EPA and DOH.

Selenium is a naturally occurring mineral element that is distributed widely in nature in most rocks and soils. The presence of selenium in drinking water can be attributed to the erosion of natural mineral deposits.

Impacted users can contact the Maui Department of Water Supply.

This news release is issued in accordance with Hawaii Revised Statutes §340E-24(b), which requires notification of previously detected contaminants in underground sources of drinking water or any public water supply.

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