The Illinois Department of Transportation has closed Illinois 100 near Grafton because of rising flood waters, and additional closing are likely within the next 48 hours.
According to IDOT spokesman Joe Monroe, Illinois 3 in Grafton also seems that it is in the path of expected flooding.
"The department will continue monitoring state roadways in the counties of Calhoun, Greene, Jersey, Madison and Randolph throughout the weekend, Monroe said. "Over the next several days we will provide updates, as warranted, when developments occur."
According to the National Weather Service, moderate flood stage on the Mississippi River at Grafton is 24 feet. As of Wednesday morning the river stood at about 25 feet. It is expected to crest, barring any unexpected rain upstream, Saturday at about 26.3 feet.
In Alton minor flood stage is 21 feet. The river there, as of Wednesday morning, stood at 23.78 feet. It is expected to crest at 26 feet Saturday, about three feet short of moderate flood stage.
But flooding doesn't seem to be a serious problem on the St. Louis riverfront or to the south.
As of Monday, the river was at 28.64 feet, nearly a foot and a half below minor flood stage, 30 feet. It is expected to crest Saturday at 32 feet. National Weather Service Hydrologist Mark Fuchs said that is enough water to cover Lenore K. Sullivan Boulevard on the St. Louis Riverfront and to reach the lower entrance to the Laclede's Landing parking structure. But there is no threat that levees in the area will be breached.
Fuchs said the reason the Mississippi isn't overflowing at St. Louis is because the river has more capacity there than to the north and also because, while the upper Mississippi River is flooding, the Missouri river isn't. Usually, Fuchs said, it takes the Mississippi and the Missouri flooding at the same time to cause severe water flow issues at St. Louis.
Motorists in the Grafton area should follow posted detour signs to take Illinois 3, Illinois 109 and Illinois 16 to get around the Illinois 100 closure.
Contact reporter Scott Wuerz at firstname.lastname@example.org or call 239-2626.