How the Iowa City area built a resilient flood control system

IOWA CITY — For nearly a month, Iowa City’s gateway from Interstate 80 sat waterlogged. Nearby, floodwaters destroyed the region’s premier performing arts center and damaged the home of one of Iowa’s most valued paintings, Jackson Pollock’s “Mural.”

To protect against another devastating flood, the Iowa City metro area looked up — literally and figuratively. A project that cost more than $40 million to elevate Dubuque Street and the Park Road Bridge over 8 feet higher wrapped in 2018. A new Hancher Auditorium, costing $176 million in federal and state dollars, insurance and donations, opened on higher ground in 2016. A new $50 million Stanley Art Museum, paid for with state bonds and gifts, opened outside the 500-year flood plain last year.

On June 15, 2008, the Iowa River crested in Iowa City at a record 31.53 feet. Major flood stage is just 25 feet. The flood caused more than $270 million in damage to the area, with the University of Iowa, which straddles the river, bearing the brunt of the damage.

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Recovering from the flood and imagining a flood control system in the metro area took a collaborative approach. The UI, Iowa City and Coralville “were trying to help each other left and right” in the aftermath, said Rod Lehnertz, the university’s senior vice president for finance and operations, as well as university architect.

“A lot of the recovery was in coordination. We weren’t alone in suffering through this flood,” said Lehnertz, who was part of a core team charged with recovering the campus from the flood.

Over the decade after the flood, the cities of Iowa City and Coralville, along with the UI, worked on various flood control projects to protect the cities and campus from future disasters while also embracing the Iowa River as a key feature.

All three communities have since completed their flood control projects.

“We all felt the pain that summer — there's no doubt about it,” Lehnertz said. “I'm very proud of how we recovered, and I wouldn't want to do it again. I look back and wonder how we did it. But it is something for the university and for our communities to be proud of 15 years later.”

Iowa City’s recovery approach

In Iowa City, there were four main parts of recovery: removing hazards, updating the building code, raising Dubuque Street and consolidating the two wastewater plants.

Among the first parts of recovery was to get people out of harm’s way, said Ron Knoche, Iowa City’s public works director. There were two neighborhoods impacted the most by the flood, and this is largely where property buyouts occurred in the years after.

To date, the city has purchased 104 properties and continues to pursue buyouts, Knoche said.

A majority of homes purchased after the flood were in the “Mosquito Flats” and Idyllwild neighborhoods through a voluntary program funded by federal and state dollars. Mosquito Flats is in the Manor Drive/Normandy Drive area, and Idyllwild is between Taft Speedway and Foster Road.

These homes, except for the historic Ned Ashton House, were demolished and are being maintained as green space. Since the program wrapped up, the city has purchased a handful of additional homes, including a home at Manor Drive in February.

The city also modified its building code requirements to reduce future flood risk, Knoche said. Typical construction in the flood plain is one foot above a 100-year event, Knoche said. Iowa City modified its code to be one foot above a 500-year event.

Knoche said residents have asked why it was important to change building codes.

“I think the value in looking at the resiliency as we move forward is … as we look at redevelopment in those areas, the code requirements help remind folks kind of what can happen,” Knoche said.

There were two major projects part of Iowa City’s recovery. Knoche said these two projects are the largest capital project the city has ever undertaken.

The $40.5 million Gateway Project included raising Dubuque Street to protect against 100-year flood levels, as well as replacing and elevating the Park Road Bridge. The street and bridge had to be closed several times since a 1993 flood, impacting travel of a thoroughfare used by thousands of university employees, students and residents.

The other project was consolidating the city's north wastewater plant — where Riverfront Crossings Park is now — with the south plant on Napoleon Street. This project cost $45.6 million and was completed in 2014, Knoche said.

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Voters approved a local-option sales tax to help fund flood recovery, which expired in 2013. More than $34 million was generated for the two high-priority projects.

“Those two projects are key not only to the future resilience but also the future development of our community,” Knoche said.

Coralville’s recovery approach

Conversations in Coralville on how to recover from the 2008 flood actually started before the flood, city engineer Scott Larson said. The city had its primary engineering consultant, HR Green, monitor what was happening as water was rising.

“During the flood event and then right after, we had a lot of information from our consultants, and we were able to start immediately thinking about what projects do we need to invest in,” Larson said.

One of the bigger projects was reconstruction and raising of First Avenue and the bridge over Clear Creek, Larson said.

Other projects included backflow prevention, sluice gates, stormwater pump stations, earthen berms, permanent and removable flood walls and elevating a portion of Fifth Street. The permanent and removable flood walls are largely along where the Iowa River and Clear Creek meet, near First Avenue and Second Street.

The city also completed property buyouts along Edgewater Drive, turning the area into park space.

“Instead of 20 plus homes that were at significant risk of flooding and many had flooded multiple times before 2008, now we have a green park corridor,” Larson said.

The city completed its flood control system in 2018, a decade after the flood. Funding for these projects included city, state and federal dollars.

“We're super fortunate to be past where we're still trying to get funding to build our flood mitigation projects, and we've built what we needed to do,” Larson said. “Now we're in that ‘stay prepared, be ready’ and then make sure we're maintaining our entire flood mitigation system.”

UI’s recovery approach

The university faced eight years of coordination and recovery from the 2008 flood, including 435 meetings among the core flood recovery team, Lehnertz said.

Immediately after the flood, the focus was on working with the state and federal government to fix short-term challenges. By fall 2009, the university was able to start long-term and permanent recovery, Lehnertz said.

There were 22 major buildings on campus that flooded. The recovery work included replacement projects, as well as “repair and protect” projects, Lehnertz said. The projects were largely paid for with Federal Emergency Management Agency dollars, in addition to other state and federal grants.

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“We could not have recovered this campus without our partners at FEMA and the federal government,” Lehnertz said.

The Iowa Memorial Union has a permanent wall system around the outside of the building that created a new plaza. Lehnertz said this “protects the building from flooding, but it also added a place for students to gather outside at a safe distance from the river.”

Walkways on both sides of the river were replaced with wider sidewalks.

Eight years after the flood in fall 2016, the university celebrated the opening of three replacement buildings — Hancher Auditorium, Voxman Music Building and the Visual Arts Building.

“It was a series of recoveries over that eight years and then culminating in the christening of those new replacement buildings that symbolically completed our flood recovery,” Lehnertz said.

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The Stanley Museum of Art, which opened in August 2022, was “really our final recovery project” but it was not part of the work partly covered by FEMA, Lehnertz said. Fundraising and university bonds paid for the $50 million project.

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Embracing the Iowa River

All three communities highlighted the importance of embracing the Iowa River as part of the flood recovery approaches, including adding green space along the river.

Riverfront Crossings Park is where Iowa City’s north wastewater plant used to be. Now, it is a major park area with trails, nature playground and wetlands that highlight the riverfront. The park was designed to protect neighboring residential and commercial properties from flooding.

The university’s recovery philosophy was “not to run away from the river but to make ourselves safe from it, to make ourselves a model for protection from flooding,” Lehnertz said.

“When the river hit us in the face, it was an amazingly painful event and survival. However, the river is what also makes the university very special,” Lehnertz said.

Lehnertz said the university will continue to do projects along the river with flood protection and mitigation in mind.

“We live with the river — we're not running from it,” Lehnertz said. “But … we design for the next flood, not the last flood."

Embracing the river was also a top priority for Coralville, Larson said. This included a combination of permanent and temporary flood walls designed to protect residential and commercial businesses while also providing access to the river and Clear Creek.

Two areas where this was done that Larson highlighted are behind Monica’s restaurant on Second Street and near the Iowa River Power restaurant on First Avenue. The nearby Iowa River Trail was added as a recreational amenity and to allow access by the city to the flood walls.

What happens when there’s another flood?

With a flood control system, there’s often not a chance to test before it’s needed. But the university had an opportunity to do just that during the severe weather in June 2014.

The UI put up miles of HESCO-brand sand barriers on new, wider walkways along the river in a couple of days, as well implement a 12-foot wall that goes around Art Building West during a flood event, Lehnertz said. The water did not go over the walkways and did not hit the barriers, Lehnertz said.

“We practice putting up those HESCO barriers regularly,” Lehnertz said. “We make sure that all of our systems are ready to go.”

Having the Coralville Lake gives the communities some time to implement their flood response. Knoche said Iowa City emergency response measures — such as implementing pump stations and adding barriers — would take less than a week.

All removable flood wall panels in Coralville could be installed in about a week using a combined crew of 20 to 25, said Eric Fisher, the city’s streets superintendent. This timeline could be accelerated by bringing on additional crews if needed.

If the same exact event were to occur again, Larson said, the Coralville areas flooded in 2008 would be dry now because the water from the Iowa River and Clear Creek would be contained.

“Everything we did here was built to protect to the 2008 plus one foot,” Larson said. “ … Even if we had a 2-inch rain event behind that flood protection, that's when the stormwater pump stations kick in.”

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