Tree roots are to blame for a sewage overflow in 'Aiea Heights last night, the city Environmental Services Department said.

Roots clogged an 8-inch vitrified clay pipe, discharging an estimated 2,800 gallons of untreated wastewater from a private cleanout. About 800 gallons was absorbed into the ground while 2,000 gallons reached a storm drain leading to 'Aiea Bay, the department said in a release.

The agency cleaned, disinfected and deodorized the affected area. The city also notified the state Department of Health Signs are posted while water sampling and monitoring are done.