Updated at 1:20 p.m. to include a quote from the Department of Health.
The Department of Water Supply says there is no public health threat and will ensure ongoing water sample testing, following the finding of Dalapon detected in South Kona water sources.
In November 2017, during routine compliance water quality monitoring, trace levels of Dalapon were detected and confirmed for the first time in the DWS 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, DWS said Monday afternoon.
The amounts of Dalapon discovered were very low, such 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).
DWS officials say the levels of Dalapon detected was significantly lower than the U.S. Environmental Protection Agency (EPA) maximum contaminant level (MCL) of 200 micrograms per liter or ppb, and therefore does not pose a risk to public health.
“These findings do not represent a health threat,” said Keith Kawaoka, Deputy Director for Environmental Health. “Our Safe Drinking Water Branch is working together with the Hawaii Department of Water Supply to closely monitor these wells and will continue to test the water being served to consumers to ensure that public health is not compromised.”
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
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.
DWS notes that the South Kona Water System continues to be in compliance with all federal and state standards for drinking water.