Updated 1pm 6/22/18
People have fled floodwaters that threaten their homes in Rock Valley, Iowa along the swollen Rock River.
Churches have been designated as emergency shelters in the Sioux County community of about 3,300 residents.
Mayor Kevin Van Otterloo says residents of about 40 homes on the north side of town were strongly encouraged to evacuate.
About 400 volunteers and emergency workers worked through the night filling sandbags and creating berms.
The National Weather Service says the Rock River is expected to crest later Friday about a foot below the 2014 record of nearly 23 feet.
The service says the river rose rapidly Wednesday after nearly 7 inches of rain fell along the Interstate 90 corridor in South Dakota.
Photo by City of Rock Valley
Mayor Kevin Van Otterloo issued a state of emergency for the City of Rock Valley due to the rising floodwaters.
Mayor Van Otterloo says despite the best efforts of the 400 plus volunteers on Thursday evening, they were not able to hold the water back.
Mandatory evacuations have been issued for parts of Rock Valley for over a dozen square blocks.
The city called for volunteers to establish berms and fill sandbags Thursday evening.
The Rock River is predicted to crest at 21.5 feet, which is the second highest crest in recent history.
The river crested at 22.72 feet in 2014 when many homes were damaged in floodwaters.