Maui County, Hawaii notified federal and state officials of the presence of a banned pesticide in the wastewater at three Monsanto Co. treatment plants during testing in 2016.
Monsanto Co. agreed to plead guilty to using, transporting and storing Penncap-M at its South Maui, Maalaea and Kaunakakai facilities in 2014, according to Maui News.
Testing in 2016 identified the presence of nitrophenol, a metabolite of methyl parathion, the active ingredient in Penncap-M.
The company must pay $10 million in fines and community service payments.
The highest concentration of nitrophenol was found at the Kihei treatment plant, followed by the Molokai and Lahaina plants, according to county spokesman Brian Perry. The chemical was not found in the Kahului treatment plant.
The county does not know how the chemical got into the wastewater. It may have come from excretions from contaminated workers, through the air or purposefully deposited in the sewer system, according to Maui News.
The treated wastewater with the nitrophenol would have gone into the injection wells at the facilities, but whether it reached the ocean is not known.
The Kihei facility test on Oct. 4 2016 showed 53.72 ppb/liter of nitrophenol, reported Maui News. The Kaunakakai and Lahaina facilities both were tested on Oct. 18 2016, with 48.94 ppb/liter and 10.41 ppb/liter, respectively.
Testing in February, May and August of 2017 did not show the presence of nitrophenol, however.
On Nov. 21, Monsanto agreed to plead guilty to a misdemeanor offense of spraying a banned pesticide, methyl parathion, the active ingredient in Penncap-M, on 2 acres of corn seed and research crops at its Valley Farm facility in Kihei in 2014.
The company has agreed to be on probation for two years and to pay the maximum possible fine of $200,000.
Monsanto also agreed to deferred prosecution related to two felony counts of unlawfully storing acute hazardous waste, according to Maui News. Monsanto will pay a $6 million criminal fine and $4 million in community service payments.
The agreement still needs to be approved by a U.S. District Court judge in Hawaii.