The discharge of about 1,280 gallons of wastewater out of a manhole at Victoria and Beretania streets Thursday afternoon was being blamed on a blockage caused by tree roots.

It was the third release of sewage water in as many days on Oahu. The spill began at about 12:53 p.m. and was stopped within the hour. About 700 of the 1,280 gallons entered the stormwater system, the city Department of Environmental Services said. An Environmental Services crew cleaned, disinfected and deodorized the affected area.

The state Department of Health was notified of the incident but chose to waive the requirement for signage and water sampling associated with the discharge.

At about 8:30 a.m. Wednesday a wastewater overflow was reported at Mayor Wright Homes at 521 Kukui St. The overflow was stopped at about 10:09 a.m., after approximately 3,345 gallons of wastewater was released — more than 3,100 gallons entering the stormwater system.

The cause of the discharge remains under investigation.

An Environmental Services crew cleaned, disinfected and deodorized affected areas, and signs were placed along various points of Nuuanu Stream. Water samples are being collected, and the public is advised to heed warning signs.

At about 9:30 p.m. Tuesday about 4,275 gallons of wastewater overflowed at 319 Walker Ave. in Wahiawa, most of which entered a storm drain at the end of Olive Avenue, the city said. An Environmental Services crew retrieved about 300 gallons.

That discharge is being blamed on the buildup of grease in a sewer line.