Trooper Guy Gill said Mello was pulled over for a lane violation just after midnight Sunday when the trooper smelled alcohol in the car.
Mello, who was driving with several passengers, volunteered to take the field sobriety test. The trooper determined Mello was impaired and arrested him.
The council member was processed for DUI, then released.
Mello has not been charged; the Pierce County Prosecutor's Office will decide whether to file charges.