She was rushed to hospital but died five days later.
The girl’s death is not being treated as suspicious by police,but investigators want to speak to a woman who may have seen the child leaving the playground between 2.30pm and 2.45pm.
Located on the south bank of the Maribyrnong River,Footscray Park is a popular picnic and play spot for families.
Victoria Police said the drowned girl had dark hair and was wearing a khaki jacket at the time.
The appeal for witnesses comes four days after a two-year-old boy was left fighting for life after beingpulled from a swimming pool at a Crown hotel in Southbank.
Emergency services were called to the hotel complex in Whiteman Street about 10pm on Friday,following reports a boy had been discovered unresponsive in the pool.
The toddler was treated at the scene by paramedics and taken to the Royal Children’s Hospital.