CEDAR RAPIDS, Iowa (CNN) -- Floodwaters inundated Iowa City and the University of Iowa arts campus on Sunday despite what one official called a "Herculean effort" to hold back the water with sandbags. 

Residents surround Lt. Tobey Harrison at a Cedar Rapids checkpoint as they wait to see their homes Sunday. 

"We've had the [National Guard] working next to prisoner inmates, sandbagging," said David Jackson, the university's facilities manager. "Students, faculty and staff, leaders of the university, the president of the university -- out sandbagging." 

Some 500 to 600 homes were ordered to evacuate and others faced a voluntary evacuation order through the morning, said Iowa City Mayor Regenia Bailey. 

The Iowa River in Iowa City crested at 31.5 feet and was expected to remain at that level until Monday, city and state officials said Sunday. 

Classes at the university have been suspended until next Sunday, according to its Web site. 

"All of our theaters, our music building, Clapp Recital Hall, our fine arts building [the] new Art Building West designed by Stephen Holl, has taken on significant water as well," said Sally Mason, president of the university. "Fortunately we were able to save all the art," she said. 

The art was placed in crates shipped out of state last week. 

"We anticipated the worst a week ago." At least 8 feet of water rushed through the campus, officials said. Among the school's 30,000 students, Ann Barber told CNN she has been sandbagging for nearly seven days. 

"It's very hard to watch the devastation of our university," she said. 
How many stidents
Among the school's 30,000 students