The Hilo Wastewater Treatment Plant, located on Hawai’i Island, discharged an estimated 607,000 gallons of effluent into Hilo Bay on June 21, 2024.
The Hawaii Clean Water Branch System described the cause as a chlorination process failure. Treatment plants use chlorination to disinfect wastewater by killing viruses and bacteria that may be in it.
The discharges released into Hilo Bay did not undergo chlorination.
The spill started at 8:15 am local time on June 21, 2024 and process was restored at 12:30 pm local time on June 21, 2024.
The Department of Health issued a water quality advisory for Hilo Bay, and advised the public to stay out of the affected water until the advisory has been cancelled.
The Hilo Wastewater Treatment Plant is currently part of a consent decree served by the U.S. Environmental Protection Agency (EPA) to ensure that pollution discharge requirements are met at the Hilo plant, along with two other plants located on the island of Hawai’i.
The consent decree, served April 1, 2024, states that the EPA identified significant operation and maintenance deficiencies which have affected treatment systems, leading to violations of limitations on what the plants can discharge as well as sewer overflows.
The order requirements include the rehabilitation and repair of the Hilo wastewater treatment plant.
The EPA has worked cooperatively with the County and Hawai’i Department of Health to identify needs for capital improvements, strengthened planning efforts and asset management of the county’s wastewater infrastructure systems.
