Authorities have identified a Dubuque man who went missing on the Mississippi River as they continued to search for him Thursday. Emergency crews spent Thursday searching for 51 year old Alan Hartig but have been unable to locate him. He is presumed to have drowned. The Grant County Sheriff’s department received a report at about 5:30 p.m. Wednesday of a man who had gone missing on the Mississippi River. Reports say Hartig was in Wisconsin waters just off the shore of Finley’s Landing in Dubuque County. He was wading in shallow water with his pontoon beached on a sand bar. The pontoon dislodged and began drifting down river, and he was last seen pursuing it in the shallow waters. The empty pontoon was recovered a short distance down river. Multiple agencies immediately began searching for Hartig, which continued into the evening before eventually being suspended. Authorities resumed their search Thursday but have been unable to locate Hartig.