Heavy rain triggers wastewater spills on Oahu, Kauai

HONOLULU (HawaiiNewsNow) – Heavy rain Friday triggered multiple wastewater spills on Oahu and a large overflow on Kauai, according to city and county officials.

The Honolulu Department of Environmental Services said storm runoff and increased inflow into the sewer system led to several overflows:

• Wahiawa Wastewater Treatment Plant: Storage tanks reached capacity around 12:44 p.m., resulting in a spill into Lake Wilson.
• Kaneohe Tunnel Influent Facility: High flows caused a manhole overflow into Kawa Stream at about 2:45 p.m.
• Kailua Regional Wastewater Treatment Plant: At around 9:45 p.m., primary clarifiers were overwhelmed, leading to a discharge into Nuupia Pond.

City officials said crews are responding to the sites and are still calculating the total volume of wastewater released.

On Kauai, officials reported a spill at the Waimea Wastewater Treatment Plant (WWTP) totaling about 285,750 gallons, occurring from 8 p.m. Friday to 6 a.m. Saturday.

Officials said the overflow came from the effluent tank after wastewater had already gone through biological treatment and UV disinfection. The spill was confined on-site, though some overflow may have entered nearby drainage ditches that do not connect to state waters. Additional disinfection was completed in affected areas.

Officials warned additional spills could occur until the storm passes. The Wastewater Management Division said it is working on immediate repair projects and coordinating with the Hawaii Department of Health on options to expand capacity to better handle storm-related flows.

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