The child was holding onto her mother.
Police in the state issued a statement saying that the woman in Beaumont, east of Houston, had died trying to escape the floodwaters but had managed to get her daughter to safety, who was recovered by rescue teams.
"Rescue divers in a Zodiac boat, spotted the mother floating with the small child".
Penisson said the child was now in stable condition at Christus St. Elizabeth Hospital.
The mother was unresponsive and efforts to revive her failed.
The report said the rescue boat got to the scene just in the nick of time as the mother and daughter were about to go under a railroad trestle.
Authorities have rescued a shivering toddler clinging to the body of her drowned mother in a rain-swollen canal in south-east Texas.
First responders performed CPR until they could get her to an ambulance.
Beaumont police officials said the toddler was doing well and had been reunited with family. Water was up to the trestle and first responders would not have been able to save the child if they'd floated under it. "The baby also had a backpack that was helping her float on her back, and she was holding on to her mom".
The Beaumont Police Department has identified the woman as 41-year-old Colette Sulcer.
Department spokesperson Officer Carol Riley told People that the woman "absolutely saved the child's life".
At least 10 people, including those in Beaumont and Jasper County, have been killed by Harvey since Friday, when it made landfall in Texas as a Category 4 hurricane.
Emergency workers continued on Wednesday to rescue people as floodwaters continue to rise after six consecutive days of the tropical storm in southeast Texas. Harvey has since weakened to a tropical storm. The storm has now moved into southwest Louisiana, according to latest reports.