Thousands Evacuated, National Guard Deployed as Iowa Braces for Major Flooding More than 1,400 homes and 400 businesses are threatened in Cedar Rapids, Iowa.

 -- Residents of Cedar Rapids, Iowa watched warily Tuesday as floodwaters continued to rise to levels not seen since record flooding in 2008 that caused some $10 billion of damages and claimed one life.

The Cedar River approached 22 ft. in the city Tuesday morning, on its way to a crest of 23 ft later in the day, according to National Weather Service predictions. The water was causing major flooding already, with a growing list of streets and highways being shut down

The city laid some 250,000 sandbags in preparation of Tuesday's crest, constructing 10 miles of temporary levees around low-lying areas of the city.

"Residents are reminded that 16 feet is considered major flooding, and the river is predicted to crest at 23 feet," city officials warned. "Temporary flood control measures have been constructed over the last 2-3 days in an effort to contain rising water, but are no guarantee of safety."

"We have seen the system working," mayor Ron Corbett told KCRG, a local ABC affiliate. "We built this [barrier] to 26 feet... so it isn't an issue of the water going over the temporary system. It's really more of pressure over a 48-hour period that we're worried about a breach or a compromise in the system."

Even as the mayor praised the city's preparations, he warned about the lingering danger of the floodwaters.

About 1,400 homes and 400 business could be inundated if the temporary flood wall fails, the Des Moines Register reported. A breach in the barrier could send a dangerous surge of water streaming into the city.

"The crest is the peak but the river is going to fall slower than it has risen," Corbett said. "So really we have this critical period now. If we can get through this, if the system works, we will have saved Cedar Rapids from the second largest disaster in our community's history."

Members of Iowa's National Guard arrived in the city on Monday to assist in the flood preparations, KCRG reported. Guardsmen helped police patrol evacuated areas, and enforce an 8 p.m. curfew.

Col. Greg Hapgood of the Iowa National Guard told KCRG the hard lessons from 2008's disaster helped bring about a higher level of preparedness.

"2016 is a totally different year," he said. "The water is not nearly as high. The city of Cedar Rapids has done an amazing job preparing for it. They are so far ahead of this particular flood than 2008, when they were trying to play catch up."