City and County of Honolulu, HI

05/18/2024 | Press release | Distributed by Public on 05/18/2024 20:08

05/18/24 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

HONOLULU - An elevated count of a specific type of bacteria, enterococcus, was measured in a single sample of treated effluent taken at the Kailua Regional Wastewater Treatment Plant (WWTP) May 17, 2024, at 10:13 a.m., which was 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 times greater than the average daily flow, and are believed to be the cause of the May 17 result. The city continues to manage these unusually high flows through use of the Kaneohe-Kailua Tunnel.

The sample was 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 most recent prior single sample taken May 16, 2024, was within the normal range and within permit limitations.

The city initiated collecting additional daily samples at the seven (7) shoreline stations located near the WWTP. Additionally, 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. This notification will be updated upon confirmation of the city's additional monitoring efforts.

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.


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