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., and May 18, 2024, at 8:28 a.m. Both 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 flows at the treatment plant that were approximately five and four times greater than the average daily flow during the collection of the May 17 and May 18 samples, respectively. These high flow conditions are believed to be the cause of both sample results. The city continues to manage these unusually high flows to the treatment plant through use of the Kaneohe-Kailua Tunnel.
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—
