Madison and a passer-by, 28-year-old Lyle Eagletail, rushed in and saved the boy, but they were then dragged away by the river. Crews recovered Madison's body on Friday, and local ABC affiliate KSFY reports that Eagletail's body was recovered Saturday.
Allisa Huntsman, Madison's aunt, heard the news from her father Thursday evening. She was in shock.
"It took a long time to sink in," said Huntsman, of Utah County. "It's a miracle [Garrett's] alive. We're so grateful."
Huntsman remembers Madison as a shy girl, but she was always loving and close to her four siblings.
"She was always concerned about other people's feelings. Sometimes she would do something that was not a big deal at all and was afraid it would hurt my feelings," but it was always all right, Huntsman said. "I don't think there's anyone who wouldn't like Madison."
Madison was also loved reading and storytelling. A YouTube video on her account shows off her young imagination "The Lost Tales," a trailer for a story she and her sister made up about Madison saving her animal friends from an evil wizard.
The trailer teasingly asks whether Madison will ever save her friends. "Yes she will," her family wrote on a post about the video on Saturday.
In addition to a passion for knitting, stories and music she played the French horn in her South Dakota high school's marching band Madison was also very spiritual, and was looking forward to serving a mission for The Church of Jesus Christ of Latter-day Saints. She didn't have any destination in mind in particular, she just wanted to tell people about the LDS gospel, Huntsman said.
Her family wrote on the memorial website that they are "positive she will serve a mission in heaven."
Madison and her family moved to Vermillion, S.D., from Orem about three years ago, according to her uncle, Jon Wallace.
Huntsman said she is grateful she had a chance to see her niece at Christmas. The family, scattered across several states, still reunites in Utah County for the holidays. Now they're preparing to see each other again to say goodbye to Madison though they're asking for help to cover those expenses.
Her family set up the Madison Wallace Family Fund at Wells Fargo bank for anyone who wants to help them pay for funeral and travel expenses. Her father, who is pursuing a master's degree in printmaking, is currently unemployed, according to a Facebook page about the fund.
As of Saturday morning, the family was almost halfway to their goal, according to a Facebook page about the fund. More information is available at www.madisonwallacefund.com.
The Associated Press contributed to this story.