Officials close campsites, adjust outflow as Coralville Lake rises

EDITOR'S NOTE: An earlier version of this story included an incorrect outflow figure regarding a boating ban on the Coralville Reservoir. The figure has been corrected as of 9:24 a.m. Friday, June 26, 2015.

CORALVILLE — Heavy rainfall in Eastern Iowa has officials at Coralville Lake making adjustments to reduce outflow at the reservoir for the next few days.

The decision has some officials downstream of the lake concerned the outflow reduction, which is expected to bring the lake behind the reservoir up to about 701 feet above sea level, will limit flexibility in water management in the event of any future rain events.

The Army Corps of Engineers, which manages the Coralville reservoir, on Thursday reduced outflow from 6,000 cubic feet per second to 1,000 cfs, where it will remain until Sunday, according the Corps website.

Janet Lewis, Supervisory Park Ranger with Coralville Lake, said outflow at the reservoir was reduced to lessen the impact downstream, in particular near Kalona, where the English River is swelling to its banks.

The lake, which was sitting at about 693.9 feet above sea level Thursday morning, is expected to crest around July 3 at just below 701 feet as water continues to flow in from the Iowa River Basin. The reservoir spillway sits at 712 feet.

'The lake level will be coming up so we are planning for, and making adjustments for, a level around 700 feet, maybe a little bit more than that,' Lewis said.

However, Johnson County Emergency Manager Dave Wilson said he feels the reduced outflow is unnecessary and limits the lake's ability to hold additional water in the coming days.

'Obviously that frustrates us,' Wilson said. 'We would rather they maintain 6000 cubic feet per second out and keep flood storage available at the lake when we don't know what the weather is going to hold in the next 7 to 10 days ... We feel we should save that capacity for later.'

It's not until outflow surpasses 10,000 cfs that the Iowa River swells beyond its banks below the reservoir — Dubuque Street is submerged at roughly 11,500 cfs and a boating ban is implemented around 15,000 cfs, Wilson said.

Holding back water in the Coralville Lake also impacts the nearby campgrounds and lake officials are planning to reduce the number of campsites available surrounding the lake for the Fourth of July weekend.

'That is going to impact some low-lying campsites.'

Lewis said between 30-35 campsites — mostly RV sites in the Sugar Bottom and West Overlook areas — will be closed during the July 4 weekend, which is the lake's busiest weekend by far. The campsites are traditionally filled on a first come first served basis and cost roughly $20 per night.

The beaches in the West Overlook, Sandy Beach and Sugar Bottom areas also will be closed, along with some boat ramps, she said.

Boating will still be allowed on the lake, which doesn't close until water reaches roughly the 710 feet level, but boaters are urged to exercise added caution on the water.

Rising water levels can dredge up logs and other debris into the lake and campsite amenities like picnic tables or grill fixtures can become hidden below the surface.

'We always encourage boaters to be more cautious, there are submerged hazards in some of those camp areas,' Lewis said.

High water levels have become an almost annual occurrence on the Coralville Lake, which ideally sits at 683 feet in the summer. The water behind the reservoir crested above 708 feet above sea level the last two summers. Those two summers saw some flooding above and below the reservoir, closures at the Coralville Lake and a boating ban on the Iowa River below the dam.

The most memorable year was 2008, when the lake crested at a record-setting 717.2 feet that June, causing severe flooding along the Iowa River.

'We are getting a lot of practice,' Lewis said. 'It's becoming somewhat of a routine.'