Sunday Flood Briefing: Water Levels Now Expected Not to Top Spillway, Rural Johnson County Evacuations Ordered

Via Johnson County

With 24 hours of dry weather, and no measurable moisture forecasted for the next 24 hours, local officials welcomed an updated projection from the Army Corps of Engineers that lowered the expected crest on the Coralville Reservoir.  

During the morning briefing of area entities, governments and agencies working to address flood conditions, the Corps reported that the current projection is that the Reservoir will crest on June 7 at 711.5 feet.  This is 1.3 feet lower than the projection provided on Saturday and is slightly lower than the 712 foot maximum capacity.  At this level, the water will not overtop the spillway.

The Corps also reported that current inflow to the Reservoir is at 32,000 cubic feet per second (cfs) and the outflow is at 18,000 cfs.  The peak outflow is expected to reach 19,500 cfs at the peak on June 7. The United States Geological Service (USGS) reported that the flow at the Burlington Street Dam in Iowa City is currently 19,200 cfs as a result of additional input from creeks and streams.

Based on yesterday’s forecast, Shane Hubbard, hazard modeler for Emergency Management, estimated that approximately 64 structures countywide could be impacted by the flooding.  The structures have a value estimated at $23 million and could see damages in the area of $2 million.  

The projections do not take into account protection installed to control the water. Approximately 30 of the structures are in the unincorporated areas of Johnson County.  Additional estimates include up to 15,000 tons of debris and 20 miles of road segments that could be inundated.

Boating and swimming continue to be prohibited on the Iowa River south of the Coralville Dam.  In the last 24 hours, officials have responded to calls of people, including children, being in or near the water.  In one instance, individuals were attempting to launch a canoe onto the river.  All officials were encouraged to continue to warn residents of the dangers in or near the floodwater.

Water activities continue to be permitted at the Coralville Reservoir, Lake MacBride and the Cedar River. The Corps will continue to monitor the situation at the Reservoir and may close several campgrounds as well as access to the dam on June 3 and June 4.

The University of Iowa, and the Cities of Coralville and Iowa City reported progress with flood preparations.  The University has installed seven miles of Hesko barriers and is prepared to install additional protections as needed.  Iowa City is evaluating the need to close Rocky Shore Drive on Monday or Tuesday.  

Johnson County issued two additional mandatory evacuations on Saturday.  One was for Sand Road SE from 560th Street to Street to Highway 22 and the second was for Lola Lane SE and several properties on Tri County Bridge Road in far southern Johnson County.  The affected portion of Sand Road SE also joined the list of County road closures.  The complete list of closures is on the County’s website (www.johnson-county.com).  Several properties on Ely Road and Swan Lake Road near the Reservoir are under voluntary evacuation and are being monitored as the water The United Way continues to operate the emergency volunteer center and disaster call center at the Johnson County Fairgrounds, 4265 Oak Crest Hill Rd SE, Iowa City.  

While the shelter has not been needed, volunteers stand ready to open it if the need arises.  Those needing assistance or wanting to volunteer should contact the center at 319-337-8657. Iowa City residents needing sandbags should call the center.  Residents of rural Johnson County can pick up sandbags at the Secondary Roads location 4818 Melrose Avenue West, Iowa City.  Residents of other municipalities can contact their respective city halls.

The next Emergency Operations Center update will be held on Monday morning with a press conference to follow.