The 14-month-old boy fell down into an open manhole in Kawameeh Park in Union last month.
The manhole cover had been swept aside by floodwaters.
The boy's mom says they were playing when he suddenly disappeared from her sight.
"As clear as I see him is as clear as I don't. He's just gone, gone," she told "Good Morning America." "There was no sign of my son, and so I ran. And the only thing you could hear was, 'Mama, mama,' and I'm going, 'Where did he go?'"
"Henry! Henry! Henry!" she could be heard screaming as she called 911. "I need someone. I need someone to come. There's an open manhole."
But while she was on the call, she noticed that her boy began to drift away. She then jumped into the hole and grabbed the child before water could sweep him down a tunnel and into an underground area that would have been too small to access.
"She put down the phone, jumped into the manhole and was able to reach him before he got to a part of the sewer that was too small for her to get into," said Anthony Schmidtberg of the Union Fire Department.
They were taken to the hospital, but neither was seriously hurt.
RELATED | Video shows moment after mom jumps into manhole to save 1-year-old boy
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