The number of confirmed fatalities from the flooding in Colorado stands at four but is expected to rise.
The widespread flooding, from the Rocky Mountain foothills to the plains of northeastern Colorado, has led to hundreds of missing person reports.
But officials expect the numbers to drop as cell phone service is restored and those unaccounted for check in.
People who have been out of touch for several days are being asked to call the Red Cross.
Meanwhile, more rain is threatening to complicate search and rescue efforts.
Twenty military helicopters planned to expand the search Sunday from Boulder County east to Fort Morgan, but a forecast of up 2 to inches of rain is putting that in doubt.