IOWA CITY, Iowa (AP) - The University of Iowa and cities along the Iowa River installed flood barriers Thursday amid concern that a key reservoir could overflow and inundate the area next week.
Coralville Lake, a reservoir built to control flooding on the river, was projected to crest next week less than one foot below its emergency spillway. Authorities said they can limit flood damage as long as water doesn't rise above the spillway.
But emergency managers cautioned that rainfall in coming days could change the forecast and cause waters to top the spillway, which was breached during devastating floods of 2008 and 1993. They said that no rain was expected until at least Saturday evening, but after that a forecast of possible storms was concerning.
"The lake is doing exactly what it is supposed to do right now: holding those waters back," said Dee Goldman, operations manager at the lake. "But once we get within a foot or so of that spillway crest, then we really start looking at the sky and depending on Mother Nature. It's really in their hands at that point."
The record 2008 flood caused hundreds of millions of dollars in damage to the university, closing key buildings such as its art museum and music school. Hundreds of homes and businesses in Iowa City and surrounding areas were also ravaged by flood waters. City and university officials say they are in better position to fight flooding now, after residents accepted federal buyouts of low-lying homes and new safety measures have been adopted.
Workers finished installing a four-foot temporary flood barrier along the banks of the Iowa River on the university campus, a measure that wasn't deployed in 2008. A new 12-foot flood wall also went up to protect an art building rebuilt after sustaining heavy damage in the 2008 flood.
Heavy rains in the upper Midwest have caused the Mississippi and many of its tributaries to rise sharply, causing significant flooding in Iowa, Illinois and in Missouri north of the confluence with the Missouri River near St. Louis.
A Mississippi River lock and dam was set to be shut, the U.S. Army Corps of Engineers said, as it tries to protect the town of Clarksville, Missouri, where the river is already 6 feet above flood stage and rising.
The rising rivers cast a shadow over the Fourth of July weekend.
Officials in Davenport, Iowa, cancelled their Red, White & Boom fireworks display that had been scheduled Thursday night over the Mississippi River, which is expected to crest there Friday and drop slowly through next week. Some downtown streets were closed, but city officials say the barriers they have installed should limit the damage.
The popular National Tom Sawyer Days festival in Hannibal, Missouri, will go on as planned, although parts of a highway south of town are expected to be closed because of flooding. Iowa City's popular three-day jazz festival started Thursday, but attendees had to take an alternate route to downtown after the city closed a key street.
Authorities warned boaters, who are expected at Coralville Lake in large numbers over the weekend, to use caution because of heavy debris. Boating has been banned on the Iowa River below the lake.
The Corps of Engineers, which manages the lake, opened the gates Thursday to increase the outflow of water to 18,000 cubic feet per second, near its maximum.
The lake, six miles north of Iowa City, is rising as a result of heavy June rainfall. The Iowa River upstream has reached record levels in some places, and those waters are flowing into the reservoir at a rate of more than 30,000 cubic feet per second.
The lake's water levels were at nearly 704 feet on Thursday and expected to crest July 10 or July 11 at 711.3 feet, below the top of the 712-foot spillway. In 2008, the water reached 717 feet.
Associated Press writers Jim Salter and Jim Suhr in St. Louis contributed to this report.