Flood Update: Corps of Engineers Likely to Lower Dam Outflow by Week's End

Via Johnson County

Minimal rain over the weekend has aided the continued decrease in levels of area waterways, easing Johnson County officials’ immediate flooding concerns. 

According to Maren Stoflet, service hydrologist with the National Weather Service (NWS), the Iowa River Basin area received less than 1/10 to 1/3 inch of rain over the last 24 hours, which had very little impact on the levels of the Iowa River and area creeks. 

Starting Tuesday night, there is a possibility of an overnight complex of showers and thunderstorms developing, Stoflet said. 

This rainfall could produce ½ inch of precipitation from Interstate 80 northward, with some areas possibly receiving 1-2 inches.

The level of the Coralville Reservoir today is at 706.30 feet, a 24-hour decrease of .66 feet, according to Dee Goldman, operations manager at the Coralville Reservoir with the U.S. Army Corps of Engineers. Water outflows and inflows continue to drop, with today’s outflow at 17,800 cubic feet per second (cfs) and inflow at 11,500 cfs. Goldman added that 37.5% of the Reservoir’s storage capacity remains available.

Jim Stiman, chief of water control for the Corps, said they are planning to cut back water outflows from the dam on June 15 to 14,000 cfs. On June 16, outflow would be reduced to 10,000 cfs and held at that level. Stiman emphasized that plans are dependent on rainfall in the area.

Janelle Rettig, chairperson of the Johnson County Board of Supervisors, said officials recognize that residents still under mandatory evacuation orders are understandably anxious about getting back to their homes to assess damage and begin recovery efforts.

However, Rettig pointed out, NWS forecasts continue to show possible rain for several days, which has her concerned.

“We  need to get that water out of the Reservoir,” she said. “We want to avoid a second crest.”

Terrence Neuzil, public information officer for Johnson County Emergency Management, agreed with Rettig’s concerns. 

“I’d rather see residents inconvenienced a bit longer than cleaning up, then having to go back and do it again if a flooding situation returns,” Neuzil said.

Sand Road SE from 560th Street to Highway 22 and Amana Road between Blain Cemetery and Highway 965 have reopened. Amana Road between Falcon and Blain Cemetery remains closed. 

Updated road information is posted on the County website at www.johnson-county.com. 

Johnson County’s three mandatory evacuation orders remain in place.

Empty sandbags for residents in rural Johnson County will continue to be available through 4:30 pm today at Johnson County Secondary Roads, 4810 Melrose Avenue West, Iowa City.

The FEMA preliminary damage assessment team, which will examine impacts to public infrastructure such as roads, bridges, waste water treatment plants, parks, schools and other public buildings, is in the area this week. These damage assessments are the first step in helping the Governor determine whether the scope of the damages are beyond what the state is capable of handling and if additional federal assistance is needed.

Dee Goldman, from the Corps, also reported that the road across the Coralville dam, as well as access to Tailwater East and Cottonwood campgrounds, will reopen tomorrow as scheduled, around noon.

The Emergency Operations Center (EOC) will conduct daily briefings through Wednesday, June 12, with press conferences following at approximately 9 am.