The 3-year-old-girl had gone missing earlier in the day and police discovered her body late in the afternoon. The accident happened just off Day Street in San Mateo.
San Mateo Police Department Lt. Pat Molloy said the child was located in the water and pulled from the lagoon. Officers and emergency personnel tried to revive the child but were unsuccessful.
Molloy said investigators will now interview the family. They will try to find out how the girl, who has other siblings, managed to get to the water.
There are a lot of other families in the area with children and the neighborhood has been hit hard by the tragedy.