Residents were advised to stay out of Kaukonahua Stream and Kaiaka Bay on the North Shore while 1.2 million gallons a day of treated waste water normally used for agricultural irrigation was diverted to those waterways early this week.

The diversion began Monday at 3:50 p.m. after a fallen tree blocked a ditch that carried irrigation water and treated effluent from Schofield Barracks Wastewater Treatment Plant. It could end as early as today.

Alec Wong, chief of the Clean Water Branch of the state Department of Health, said yesterday that warning signs were posted as a precaution, but the waste water has been through tertiary treatment, including disinfection, so it looks like drinking water and is odorless and quite clean.

“;We believe that the discharge is cleaner than the water coming from the Wahiawa Reservoir,”; Wong said yesterday. “;Because of the treatment process, the ultraviolet disinfection, there are virtually no bacteria in there.”;

Primary treatment of sewage entails screening out floating objects and removing solids that settle to the bottom. Secondary treatment uses microorganisms to remove organic matter. Tertiary treatment includes disinfection.

Tom Larabee, who lives on Kahaone Loop off Waialua Beach Road, complained yesterday that the beachfront near his house next to Kaiaka Bay smells and is filled with debris from trees and shrubs.

“;I can tell you our beach stinks,”; he said. “;The water is thick with debris. It looks like trees, nuts and branches, but it smells terrible.”;

Larabee said the beach was just cleaned up over the weekend, with workers hauling away more than 10 truckloads of branches and other debris that collected after recent storms. “;All of a sudden we had all this stuff over the beach again,”; he said.

Wong said his staff at Kaiaka Bay reported no smell in the area yesterday. He suggested that the odor reported by Larabee could be due to stagnant water or rotting leaves and wood.

Asked whether the waste-water diversion could have pulled down more debris, Wong said he did not think so because even with the discharge, the water level in the stream was low compared with stormy weather.

The waste-water diversion will end once repairs are complete on the ditch, which belongs to Dole Food Co. Hawaii.