Flood projections have been adjusted upward for the Mississippi, thanks to rain in the forecast for the upper Midwest and central Missouri.
About 2 inches of rain fell in Iowa over the weekend and more rain is in the forecast this week. And storms forecast for central Missouri could dump about three inches more of rain into the system, according to the National Weather Service.
U.S. Army Corps of Engineers spokesman Mike Petersen said flooding has been minor in the St. Louis region because -- so far -- the Missouri River hasn't contributed to the flooding situation.
"The flooding on the Mississippi River is pretty significant above Grafton," Petersen said. "But there's less potential for flooding on the lower end because there isn't a major amount of water being dumped into the Mississippi from the Missouri River."
But National Weather Service hydrologist Mark Fuchs said the Missouri River could change dramatically this week if as much rain falls as has been predicted.
"You're not going to get major flooding at St. Louis if the Missouri River isn't doing it's part," Fuchs said. "The Missouri is at least half of the equation. And, so far, it hasn't been an issue. But the water level could come up quite a bit. We should know a lot more about what is going to happen over the next 15 hours or so."
Even if it storms in Missouri over the next couple of days, leaders don't expect major flooding in St. Louis.
Petersen said the other things accounting for the lack of flooding on the lower Mississippi from St. Louis to the south are a wider channel than up north that can contain more water and flood control devices that help limit the river's impact.
"We still have lots of room in the river flood control reservoirs in the St. Louis area," Petersen said. "Even when we see major flooding in the area like we did last year, we have much more ability to contain the water than we did back in 1993."
In June 2013 the Mississippi River had the sixth-worst flood recorded on the waterway since 1785 when it topped out at 40.52 feet. The worst flood occurred in 1993 when the river reached 49.58 feet at St. Louis.
The National Weather Service adjusted its forecast at midday Monday, projecting the Mississippi would crest Saturday at 32.1 feet in St. Louis. Minor flood stage in St. Louis is 30 feet while moderate flood stage is 35 feet.
At that stage, Fuchs said, Lenore K. Sullivan Boulevard on the St. Louis riverfront would flood and the water would reach the lower entrance of the Arch parking garage.
As of Monday afternoon, the Mississippi was at 27.16 feet at St. Louis. It is expected to reach 30 feet by Thursday as rainwater from up north finds its way into the river and heads south.
Flooding is expected to be worse to the north of St. Louis.
Minor flood conditions are already have been reached at the Mel Price Lock and Dam near Alton, where the river was at 22.2 feet Monday afternoon. It was expected to crest there at 25.6 feet Friday or Saturday. But, with the new rain water factored in, the Saturday crest is expected to reach 26.3 feet.
Minor flood stage at Alton is 21 feet. Moderate flood stage is 29 feet.
At Grafton, the water was on the brink of minor flood stage Monday afternoon, which is 24 feet. The ferry across the Mississippi River there river there has been closed since the weekend due to high water. The river is expected to crest at 26.9 feet there on Saturday, well into minor flood stage. The major flood stage at Grafton is 29 feet.
The Brussels Ferry was open as of mid-day Monday. But operators said the water level was 6-8 inches from the point where Illinois 100 would close which, effectively, shuts down the ferry because traffic has nowhere to flow to the east.
According to the Illinois Department of Transportation, Illinois 96 north of Hamburg is the only highway that is currently closed due to high river conditions.
At Lock and Dam 24 about 90 miles up the river at Clarksville, Mo., the Mississippi River is already in major flood stage at 33.73 feet and Petersen said the lock is currently closed because of high water.
"We had to close Lock and Dam 24 early Sunday and we're prepared to close Lock and Dam 25 if necessary," Petersen said.
Currently, only one levee, a small agricultural barricade that protects about 1,000 acres of Missouri farm land near Clarksville, Mo., has been over-topped, Petersen said.
Some levees in Missouri that have been undergoing repairs have been covered in plastic to protect them from flood waters and 100,000 sandbags have been delivered to the Clarksville area. But Petersen said no flood barricades are currently in danger of failure.
Contact reporter Scott Wuerz at firstname.lastname@example.org or call 239-2626.