The sinkhole now measures 20 feet wide and 10 feet deep. It spans the entire width of a street and has started destroying a driveway near 25th Street and 6th Avenue.
Repairs could run close to $220,000.
City spokesman Don Gross says the collapse of a sewer is to blame, which was cause by the high water table because of flooding along the Missouri River.
The sinkhole is not the first for Council Bluffs, and Gross expects there will be more.
He says when the water table is high, water surrounds underground pipes and seeks out cracks. The process eventually creates an underground cavity, leading to a collapse.