DWS: S. Kona Drinking Water Safe Despite Presence of Dalapon

During routine compliance water quality monitoring in November 2017, trace levels of Dalapon were
detected and confirmed for the first time in the Hawai‘i County Department of Water Supply’s Keʻei Well A and Keʻei Well B.

As required, the public is to be notified whenever any previously undetected chemical contaminant is found in a groundwater source.

The DWS reassures the public that there is no health threat and will ensure ongoing water sample testing.

The amounts of Dalapon discovered were so low that the laboratory equipment was unable to quantify the exact concentration. Therefore, the November 2017 Dalapon results have been recorded as
non-quantifiable (NQ), which would place the concentration of the Dalapon between 1.0 to 2.5 micrograms per liter or parts per billion (ppb).

The levels of Dalapon detected was significantly lower than the U.S. Environmental Protection Agency maximum contaminant level (MCL) of 200 micrograms per liter or ppb, and therefore does not pose a risk to public health.

Dalapon is an herbicide used to control grasses in a wide variety of crops, including fruit trees, beans, coffee, corn, cotton and peas. It is also registered for use in a number of non-crop applications such as lawns, drainage ditches, along roadways and in industrial areas.

Per the EPA and DOH, “Some people who drink water containing Dalapon well in excess of the MCL over many years could experience minor kidney changes.”

Keʻei Well A and Keʻei Well B, along with Keʻei Well C, are backup wells in the South Kona Water System.

During normal operations, Halekiʻi Deepwell and Keʻei Well D are the primary sources.

Again, the trace levels of Dalapon detected in Keʻei Well A and Keʻei Well B were significantly lower than the EPA’s maximum contamination level and do not pose a risk to public health.

DWS will continue to work together with the DOH and plans to increase monitoring above what is
currently required by federal and state laws.

The DWS ask the public to be assured that the South Kona Water System continues to be in compliance with all federal and state standards for drinking water.

For more information, contact the DWS at (808) 961-8050 or dws@hawaiidws.org.