Watson Okubo, chief of the monitoring and analysis section of the Health Department's Clean Water Branch, said people should avoid contact with the affected waters for at least four days.

Okubo said the Fort Kamehameha wastewater treatment plant lost electrical power beginning at about 6:50 p.m. Saturday evening.

Before the power was restored, some 20,833 gallons of treated but not disinfected effluent was discharged into the ocean through the plant's outfall.

During the power outage, the treatment plant's ultraviolet disinfection unit was knocked offline, Okubo said.

Denise Emsley, a Navy spokeswoman, said ultraviolet light disinfection is normally the last step prior to effluent discharge and completes the plant's requirements to kill any residual bacteriological organisms that were not eliminated during the advanced secondary treatment process.

Effluent was discharged into Mamala Bay through the plant's 12,500-foot-long outfall line at a depth of 150 feet, Emsley said.

She said the Navy immediately notified the state Department of Health as required by the wastewater treatment plant's operating permit. It was determined that warning signs were not needed and the bypassed effluent would be naturally dispersed with minimal human health and environmental impacts, Emsley said.