Johnson County responds to flood threat

Outflows at Coralville Lake to be gradually increased; more rain in forecast

IOWA CITY – Jan Omann isn’t panicking, but she isn’t going to wait for flooding, either.

She has lived in her home on Iowa City’s Normandy Drive, with the Iowa River flowing past her backyard, since 1968, through the floods of 1993 (no water in her home) and 2008 (38 inches).

With flooding again a possibility, Omann on Tuesday afternoon was moving family photographs, movies and documents to the attic above her garage.

“I don’t know what to expect,” she said. “I just pray for no rain.”

Many local officials expressed similar sentiments Tuesday as they undertook planning for possibly significant flooding almost exactly five years after the record 2008 flood.

The Army Corps of Engineers is predicting Coralville Lake, which it oversees, will come within inches of its emergency spillway next week. Officials are not yet saying there’s a concern a major flood will occur, but with rain in the forecast all week, the threat is at least there.

“This thing can go either way,” said Rick Fosse, Iowa City’s public works director.

Iowa City removed the amusement park rides it has in City Park and was formulating plans in case conditions worsened, including for the possible closure of a flood-prone section of Dubuque Street by City Park.

The University of Iowa was taking the most action, installing temporary barriers around Mayflower Residence Hall, Art Building West and a UI water treatment plant – all in low-lying areas near the Iowa River.  (See related story.)

Coralville is comparing the forecasts with computer models it has to see where it may be vulnerable, City Administrator Kelly Hayworth said. The biggest concern right now is the neighborhoods along Clear Creek, where flood-protection efforts undertaken after the 2008 floods are not as far along as those on the Iowa River, he said.

A lot of the worry comes from the situation at Coralville Lake. The Army Corps of Engineers increased the lake’s outflow from 1,000 cubic feet per second to 3,000 cfs Monday morning and then 6,000 cfs in the afternoon in order to increase storage capacity, said Dee Goldman, the lake’s operations manager.

Outflow is expected to increase to 10,000 cfs Wednesday morning. The corps has a protocol it follows, and Goldman also said it must balance flooding concerns downstream from Iowa City when deciding whether to increase the amount of water leaving the lake.

Coralville Lake is forecast to crest at 711.28 feet above sea level on June 7. The dam’s emergency spillway is at 712 feet and has only been topped in the floods of 1993 and 2008.

That prediction takes into account the weather over the next 24 hours. There is a chance of rain in the Iowa City area each day the rest of this week.

“It’s definitely a concern,” Goldman said.

Dave Cousins, a meteorologist with the National Weather Service in the Quad Cities, said this week’s rain total could be anywhere from 2 to 5 inches in the Iowa City area, with the best chance Thursday through Friday. Next week the area is looking at normal to slightly above normal precipitation, he said.

The weather service is predicting the Iowa River in Iowa City will remain below flood stage. Cousins said that’s in part because the river’s height is determined not just by rainfall but how much water the corps is releasing from Coralville Lake.

Fosse, Iowa City’s public works director, said the situation should be manageable if lake outflow can stay at 10,000 cfs for the next two weeks. But that’s contingent on no significant rain over that period, something he acknowledged is unlikely in early June.

At this time, however, officials are not expecting a repeat of 2008 or 1993, said Dave Wilson, Johnson County’s emergency management coordinator. The flood-protection projects and home buyouts that have occurred since 2008 puts a lot less property at risk should there be flooding, he said.

“What I don’t want to undersell, though, is there’s no risk,” Wilson said. “There is a risk.”

Private property owners in flood-prone areas will want to consider their risk and take the necessary precautions, he said. Iowa City and Johnson County both have sandbags available for residents.

Johnson County Tuesday night asked the governor's office to add it to a list of 13 counties included in a disaster proclamation issued earlier in the day.Representatives from local governments, the corps and the National Weather Service discussed the flood outlook Tuesday morning. They will continue to meet each morning for the foreseeable future.

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