The U.S. Environmental Protection Agency has issued a consent order to the City and County of Honolulu to ensure pollutant discharge requirements are met at the Kailua Regional Wastewater Treatment Plant.

The “administrative order on consent” follows a previous one in December 2022, the EPA said, and is necessitated by the fact that the plant has continued to exceed National Pollutant Discharge Elimination System effluent limits for bacteria.

In April and May of this year, the plant exceeded limits for enterococcus bacteria in its effluent on 13 different days. Enterococcus is an indicator of fecal material in water and possible pathogens that can sicken swimmers.

This was a violation of the NPDES permit, according to the Hawaii Department of Health, which in June fined the city $434,350 for the discharges and late submission of a required discharge monitoring report.

Based upon condition assessments, maintenance evaluations, and additional monitoring requirements of the previous order, the EPA said it is requiring additional treatment and maintenance be performed at the treatment plant.

“This order ensures that the Kailua Treatment Plant continues to take steps to prevent any further bacteria exceedances in what the plant discharges into the ocean,” said EPA Pacific Southwest Regional Administrator Martha Guzman in a news release. “Compliance with the Clean Water Act permit is essential to protecting public health and Hawaii’s coastal waters. With our partners at Hawaii Department of Health, we will continue to provide vigilant oversight over Hawaii’s wastewater plants.”

To prevent further exceedances, EPA is requiring the facility to:

>> Install and operate new disinfection treatment technology to treat all effluent from the plant to ensure compliance with bacteria levels established in its Clean Water Act permit.

>> Perform major repairs to the biological treatment units or “biotowers” to prevent additional failures.

The city-operated Kailua treatment plant treats up to 15 million gallons per day of wastewater collected from the Ahuimanu, Kaneohe and Kailua communities. It is authorized by the NPDES permit to discharge treated wastewater to an outfall off of the Mokapu Peninsula.

The city has said it plans to install an ultraviolet disinfection system at its plant, which should be operational on or before December 2025, to significantly lower enterococcus levels.

Separately, EPA has a consent decree with Honolulu requiring upgrades to the Sand Island and Honouliuli wastewater treatment plants, which must be completed by 2035.