An employee of a metal manufacturing company found the 5-foot-long reptile Friday in the river's South Branch.
The alligator didn't try to attack anyone and was safely pulled from the river by a reptile expert, said Anne Kent, director of the city's Animal Care and Control Department.
The alligator was probably a discarded pet, officials said. It's now in the custody of the reptile expert.
The alligator was probably attracted to the river by carp, Kent said.
A coyote surprised customers when it walked into a Chicago sandwich shop last year. And police shot and killed a cougar found roaming the city in April.
