Unified Police Detective Jared Richardson says a woman who lived nearby heard what she thought was a kitten meowing in the trash bin on Tuesday morning.
She called out another woman to help her retrieve it, and the two found the baby.
Richardson says the boy was airlifted to Primary Children's Hospital in Salt Lake City, where he's now on a ventilator and fighting for his life.
Police say the 24-year-old mother later returned to the scene and told officers that she'd left the baby there about an hour before he was found.
Richardson says police detained the mother and are investigating.