CEDAR RAPIDS, Iowa – The dark, filthy water that flooded Iowa’s second-largest city finally started to recede Saturday after forcing 24,000 people to flee, but those who remained were urged to cut back on showering and flushing to save the last of their unspoiled drinking water.

A sandbagging siege saved the last of the city’s four collection wells from contamination by the record flood. But officials warned that if people didn’t cut back the water will run out within three to four days.

“Water is still our primary concern,” said Pat Ball, the city’s utilities director. “We’re still using water at a greater rate than we’re producing.”

An estimated 9.2 square miles, or 1,300 blocks, were flooded in Cedar Rapids, Fire Department spokesman Dave Koch said. Early estimates put property damage at $736 million, Koch said.

While the Cedar River ebbed in hard-hit Cedar Rapids, a levee breach in the state capital of Des Moines flooded a neighborhood of more than 200 homes, a high school and about three dozen businesses.

In Iowa City, more than 200 homes were evacuated because of the flooded Iowa River, expected to crest Monday or Tuesday. People filled thousands of sandbags at the University of Iowa but officials were conceding some buildings to the expected flooding.

“We’ve pretty much just abandoned any effort to try and protect the Arts Campus because we are just overwhelmed by the amount of water,” university spokesman Steve Parrott said. “It’s just too unsafe.” Valuable paintings have been removed from the art museum, he added.

At least three deaths in Iowa have been attributed to the storms and subsequent flooding, and 12 more have died in two recent tornadoes. The storms have prompted the governor to issue disaster proclamations for 83 of the state’s 99 counties.