The Illinois River at La Salle is expected to rise until Tuesday night.
The impact is expected to result in flooding Water Street in Peru, Dee Bennett Road between Utica and La Salle, flooding the lower parking lot of Starved Rock State Park, which is closed, and threatening the pump station in La Salle.
Heavy rainfall Saturday night and Sunday saturated already high river levels.
The river is expected to be at 30.5 feet, or 10.5 feet above flood stage, at about 7 p.m. Tuesday night, then it is expected to go down.
The river is forecast to come short of threatening structures in Utica by about 0.5 feet.
To La Salle's east, the river is predicted to reach as high as 7.5 feet above flood stage along the Illinois River in Ottawa, before it starts to go down Tuesday morning.
Flooding along the Fox River at Dayton will affect residents in Wedron as well as those downstream of the Illinois and Michigan Canal. The Fox is expected to reach as high as 5.5 feet above flood stage at about 7 p.m. Monday, before it starts going down Monday night.
Low agricultural areas are expected to flood along the Vermilion River at Leonore, as the river is expected to be about five feet above flood stage Monday night before going down.