DES MOINES — Officials in eastern Iowa on Wednesday ordered residents to evacuate some rural homes along the Iowa River because of the threat that rising water from a nearby reservoir could spill over a dam’s spillway and flood the area.
The Johnson County Emergency Management Agency issued the evacuation order for several unincorporated neighborhoods in low-lying areas due to concern about the Coralville Lake Reservoir, located several miles north of Iowa City. Recent heavy rains have caused the reservoir level to climb and projections show it will rise to within a foot of the spillway.
If it tops the spillway, water would pour uncontrolled into the Iowa River. However, scheduled increases of water flow from the reservoir will also mean low-lying areas will be subject to flooding.
“This is getting pretty serious around here,” said Johnson County Supervisor Terrence Neuzil.
The reservoir was about 10 feet below the spillway on Wednesday and rising.
An earlier projection showing that the reservoir level would exceed the spillway prompted the evacuation order, as officials planned to increase the flow of water entering the Iowa River in the next few days. Electricity and natural gas will be turned off in the affected areas.
The reservoir level is rising due to repeated thunderstorms that have dumped up to 5 inches of rain in parts of eastern Iowa. Water has topped the spillway only twice, in 1993 and 2008, and it led to significant flooding in the area.
Last year, county officials also warned the reservoir might spill over and issued an evacuation for many of the same neighborhoods. It eventually crested a few feet below the spillway.
The potential for flooding meant Iowa City officials went door-to-door Wednesday to speak with people in low-lying areas to warn them about the swollen river. Officials planned to issue recommended evacuations Wednesday for homes and businesses on the north and west side of the city. There are no mandatory evacuations in place.