Although the annual rainfall amounts have not been significantly higher in recent years, the number of large rainfall events has increased. The 14 inches of rain that fell over the course of four days in August led to one of the most costly natural disasters experienced by Ames and Iowa State.

The damage resulting from the flood of 2010 was so immense that the city of Ames does not yet have a complete cost estimate. Iowa State officials said the university suffered from $40 million to $50 million of damage.

Yet the frequency of major flooding events has caused many residents to be concerned with the ability of Ames to protect property from flooding.

“When we get a large flood like this, the waterway openings for our rivers were not big enough for the amount of water,” said Stephen Jones, ISU Extension communities specialist in civil, construction and environmental engineering.

The fact is that the physical attributes of Ames and the surrounding land combine to create an attractive floodplain in the center of the city. The shape of the watershed in northern Iowa and the row crop agriculture that covers the surrounding area respond quickly and negatively to a large, single rainfall event.

Jones said the flooding this year was due to Squaw Creek escaping its banks and joining with the Skunk River, which caused a historic backup of water.

Ames has witnessed major flooding events three times since it flooded in 1975 including 1993, 2008 and this year.

Long-time Ames resident Mayor Ann Campbell said she remembers watching the floodwaters rise in 1975 from her house south of the greek houses and about a block away from Iowa State Center.

“I was with young children at home then,” Campbell said. “I can remember being very close to the floodwaters, but the flood of 1993 is more firmly in my mind.”

Her experiences as a City Council member and mayor have allowed Campbell to understand that flood mitigation is a complex process that does not have easy solutions.

“If we were to plan Ames today would it look different? Yeah, it would,” Campbell said. “Weather patterns have changed and the city is a different shape than it was in 1993.”

As the city expanded, it effectively choked both rivers, Jones said. Builders and engineers have created choke points on both rivers, which constricts the ability of floodwaters to stay within the flood channel. Jones said although bridge engineers included a margin of safety in order to accommodate high levels of flooding, the margin wasn’t enough for the unprecedented rainfalls recently witnessed by Ames.

After the rainwater pushed over bridges and beyond flood banks, they entered parts of the ISU campus, residential buildings and businesses, some of which has been flooded before.

“At the time Iowa State Center was built, the buildings were certainly located in the Squaw Creek floodplain,” Jones said.

The combination of cheap land and a need for expansion ultimately led to the construction of Iowa State Center, which received the majority of the flood damage this year.

Hilton Coliseum was flood-proofed following the 1993 flood, but the efforts were not enough. Together with Scheman and Lied Recreation Athletic Center, the area accounts for around half of the flood recovery costs.

“It’s a risk thing,” Jones said. “You have to assess what kind of risk you are taking when you build in or near a floodplain.”

Although the city and Iowa State are in the process of obtaining a flood mitigation report similar to the one completed after 1993, Jones offered some analysis based on his extensive waterways-related research.

He said Lied could be protected with flood walls that proved useful in keeping Maple-Willow-Larch dry this year. Hilton Coliseum’s site of initial flooding was different in 2010 than in 1993, Jones said. Water seeped through the west side, Jones said, which indicates that flood mitigation strategies can be effective.

“We can’t just move these structures out of the floodplain, but we can look into a variety of flood-proofing strategies,” he said.

It is unlikely Ames will be able to afford major construction that widens the floodway, he said.

“I’ve heard a lot of discussion about whether we should raise the university,” Jones said. “It would certainly protect ISU, but you’re narrowing the floodplain. Where does that water go? Downstream to the next lowest area like Brookside, SUV or South Duff [Avenue].”

Following the 1993 flood, the city enacted flood plain development ordinances. Campbell explained that buildings constructed after the flood had to be elevated 3 feet above the flood plain area. The companies, including Target and Walmart, also had to make provisions for the detention of storm water. The city also offered incentives for buildings that erected a floodwall.

“It’s cheaper to limit development in designated floodway than year after year go in and fix up buildings,” Jones said.

The city of Cedar Falls decided to disallow future development in the floodplain following the devastating flooding of 2008. New businesses and homes will have to comply with 500-year-flood levels, which is far beyond what is required of Ames buildings.

City officials have expressed an interest in discussing new ordinances in order to protect residents and buildings from future damage. Yet officials maintain that no decisions on flood mitigation will be made until engineers and scientists formally provide data and suggestions.

Officials and residents agree that the 2010 flooding was not merely a result of the floodwaters traveling downstream from the watersheds in northern Iowa. Some Ames residents experienced flooding due to the failure of storm sewers and sanitary sewer pipes, which caused basements to flood in unprecedented numbers.

City Manager Steve Schainker said the city has to obtain a comprehensive list of basement backups, which would help the city prioritize inquiries into both the sewer and sanitary systems. He suggested that the city might need to take steps to repair problematic areas with public funds, particularly an increase in the storm water fee paid by Ames residents.

“Before we have data there are no solutions on the table,” Campbell said during a September City Council meeting.