In the worst hit parts of the town the water is five- to six-feet deep.
Up to 1,500 people have been evacuated, about a third of the town's population.
Those evacuated lived in 230 houses and a nursing home. Officials say the water has begun to recede.
"The water, the river has crested," said Marseilles Police Chief Jim Hovius. "As it begins to lower we'll allow people back in their homes, damage assessment, that sort of thing."
They are hopeful the town may be back to normal in about a week.
The U.S. Coast Guard and the Ingram Barge Company said Saturday that the Marseilles Dam is structurally sound after barges broke loose from a tugboat on the Illinois River and struck a levee on Friday.