Hawai‘i County reaches agreement with nonprofit to address treated sewage entering Big Island waters

Hawaiʻi County is taking steps to address treated sewage discharged from the Kealakehe Wastewater Treatment Plant flowing into Honokōhau Small Boat Harbor six miles south of Ellison Onizuka Kona International Airport.

Hawai‘i County reached an agreement last week with community group Hui Mālama Honokōhau after the nonprofit filed a civil lawsuit in 2023 accusing the county of violating federal laws by discharging treated sewage from its Kealakehe plant to waters around Honokōhau Bay through groundwater.

County officials confirmed Monday they will be pursuing a National Pollutant Discharge Elimination System permit after the lawsuit.

Right now, the county is waiting for the Department of Health to review their application and inform them of the specific steps needed to comply with the Clean Water Act. County officials expect to hear back from the state in the coming months.

Hawai‘i County confirms the average daily flow to the Kealakehe Wastewater Treatment Plant is approximately 1.7 million gallons.

County officials say the plant treats, oxidizes, and disinfects wastewater to meet the state and federal standards for secondary wastewater treatment, then discharges into a percolation basin, a natural disposal pit located in a permeable lava field upslope from the harbor.

The actual volume of treated water discharged from the plant varies depending on operational factors.

This agreement with the nonprofit follows a partial settlement reached last year in which the county acknowledged that it needs a Clean Water Act permit for the treatment plant’s wastewater discharges and committed to applying for the required National Pollutant Discharge Elimination System permit.

“We are thrilled that the county is finally taking responsibility to clean up its discharges and stop contaminating our water and nearshore reef ecosystems so it’s safe for our families to fish, gather, and play along our shoreline,” said Mike Nakachi, president of Hui Mālama Honokōhau.

The county has agreed to upgrade the treatment plant so that its wastewater meets the Hawai‘i Department of Health’s standards for “R-1 Recycled Water” (the highest level of treatment) and also to study options for projects that will allow the county to reuse treated wastewater, rather than dump it into a disposal pit where the polluted wastewater then flows with groundwater into the harbor.

Potential reuse projects include the use of recycled water to irrigate the Old Airport Park, to convert green waste into soil, and to establish and maintain the Kealakehe Regional Park.

“Upgrading the Kealakehe plant to produce R-1 recycled water opens up new opportunities to reuse water where it’s needed most on the leeward side,” said Environmental Management Director Wes Segawa. “I’m hopeful about what we can build together for our community.”

Nakachi said he was happy the county was moving forward with reusing its treated wastewater, saying it is a “valuable resource when used for irrigation, but highly destructive when dumped in our ocean.”

“This settlement is a win-win for the county, for our community, and for ‘āina,” Nakachi said.

The Kealakehe plant has always operated within the standards established by the state, officials stated. Per the Hawai‘i Administrative Rules, the Department of Health is responsible for approving the construction of wastewater treatment facilities in Hawaiʻi, and county officials say they rely on those standards to guide how their facilities are designed, built and operated.

“The county is taking the appropriate steps to come into compliance with the Clean Water Act by tackling wastewater pollution from Kealakehe. This will help to ensure that the Honokōhau marine ecosystem will be healthy enough to support people and wildlife for generations to come,” said Elena Bryant, associate attorney at Earthjustice representing the Hui.”

The Hui, which will be notified of the projects’ progress, is a group of Native Hawaiian cultural practitioners, fishers, paddlers, recreational ocean users, and concerned community members who use Honokōhau Harbor and nearby ocean waters.