A nurse's convention was happening at the same hotel and two nurses in attendance started CPR on the child, police said.
The rescue was caught on camera and may be too disturbing for some viewers.
The 2-year-old's mother, police said, was at the pool, but they didn't say why she didn't notice her child having trouble in the water, WXYZ reported.
The 2-year-old was taken to an area hospital, where he was treated and released, WDIV reported.
The Livonia Police Department has nominated the 9-year-old, her godmother and the nurses for a civilian award for their heroic response.
The Prosecutor's Office could file charges in the case, WXYZ reported.