A City of Evanston Parks and Recreation employee found an unresponsive person in the water south of Lee Street Beach, near 901 Edgemere Court, just after 11:30 a.m.
Evanston police officers and investigators responded and are working to identify the man, whose age was not immediately known. Authorities canvassed the surrounding area.
A preliminary investigation indicated that the man did not have obvious signs of trauma, but the Cook County Medical Examiner's Office will determine his cause and manner of death.
Officials did not immediately provide additional information.