Department of Environmental Services

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Department of Environmental Services

Ka ʻOihana Lawelawe Kaiāpuni

UPDATED: Notification of elevated bacterial level shown in single sample of treated effluent taken at Kailua Regional WWTP

Notification of elevated bacterial level shown in single sample of treated effluent taken at Kailua Regional WWTP – Updated Notification

HONOLULU – An elevated count of a specific type of bacteria, enterococcus, was measured in single samples of treated effluent taken at the Kailua Regional Wastewater Treatment Plant (WWTP) May 17, 2024, at 10:13 a.m., May 18, 2024, at 8:28 a.m., and May 19, 2024, at 9:39 a.m.  The single samples were higher than the single sample daily maximum limitation for enterococcus under the National Pollutant Discharge Elimination System (NPDES) permit for the Kailua Regional WWTP.  Sequential storm events with extremely heavy rainfall associated with the recent Kona Low event resulted in high flows at the treatment plant that impacted treatment process efficiency, and are believed to be the cause of the sample results.  Although the WWTP is still experiencing elevated flows due to inflow and infiltration from the ground being saturated with storm water, the treatment process efficiency is improving.

The samples were taken at the effluent monitoring station, within the plant, before discharging at the deep ocean outfall located approximately 5,000 feet from the shoreline at a depth of 105 feet below the surface of the water.  Enterococcus analysis requires a 24-hour test.  The single sample taken May 16 was within the normal range and within permit limitations. 

The city has been collecting additional daily samples of the treated effluent at Kailua Regional WWTP and will continue to do so until the data confirms that effluent enterococcus levels remain within the permit limit.  During this time, signs are posted to stay out of waters around the outfall. 

The city has been conducting additional daily sampling at the shoreline stations since May 14.  To date, the city’s monitoring results continue to show that there is no shoreward movement of effluent from the outfall, and the elevated bacterial results are likely being caused by storm runoff.  The state Department of Health (DOH) issued a brown water advisory for the island of O‘ahu May 16 as a result of the heavy rain, which remains in effect.  Per DOH’s brown water advisory, the public is advised to stay out of flood waters and storm water runoff.

 

—PAU—

 

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