The child was reported missing in the water at the private lake at 5 p.m., according to a release from the Indiana Department of Natural Resources.
Witnesses said the girl was swimming from a platform near the shore when she began struggling in the water.
Lifeguards were on-duty and immediately started a search, officials said.
Emergency personnel from the Portage Fire Department, Porter Fire Department, Chesterton Fire Department, Portage Police Department and Indiana Conservation Officers joined the search.
The girl's body was recovered from a section of the lake that was about 15-feet-deep by a member of the Chesterton Fire Department at around 5:30 p.m., officials said.
Kelly Solomon, 10, was pronounced dead at Porter Regional Hospital at 6:09 p.m. Sunday. The Porter County Coroner said she was from St. Paul, Minnesota.
Indiana Conservation Officers are investigating the drowning.
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