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Luther adjusts levee system after last year’s floods

The Upper Iowa River runs through Decorah and was the cause of major flooding last fall.

Annika Vande Krol ('19) I Photo Bureau

The Upper Iowa River runs through Decorah and was the cause of major flooding last fall.

Forrest Stewart, Staff Writer

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Luther College is beginning the process of raising its levee system in accordance to a recommendation from the Federal Emergency Management Agency (FEMA).

Last year, FEMA informed administration that Luther’s dike did not meet the standards necessary for accreditation from the agency. As plans for the raising develop, the school is working with experts to solidify the details of the project.

In a joint statement, Vice President for Finance and Administration Eric Runestad and Director of Facilities Services Jay Uthoff gave an update on the process.

“We are [currently] waiting on information from the latest soil borings and evaluation from the geo-tech engineers in relation to the projected height of the levee system,” Runestad and Uthoff said. “Per FEMA regulations, the engineers have to calculate the proposed levee as if water is at the top of the levee. They are working through what will happen to the soils on the college side of the levee if that were to happen.”

The levee raising is partly in response to a change in the 100-year flood map used by FEMA to set flood insurance premiums.

“When the proposed flood map becomes the map used by FEMA…our premiums will go up by a significant amount,” Runestad and Uthoff said. “This is because we are listed as protected by levee now, and that will not be the case in the future.”

According to the United States Geological Survey (USGS), the 100-year floodplain is “the area covered by a flood that statistically has a one percent chance of occurring in any given year.”

These floodplain calculations are based on recent flooding patterns and can change over time. Associate Professor of Environmental Studies and Chemistry Laura Peterson explained the importance of the changing map.

“Recently FEMA reanalyzed the flood map for Decorah [in order] to figure out what the 100 year floodplain is,” Peterson said. “Their new calculation of the 100-year flood would bring water levels higher than the dike was built to sustain.”

The expanding of the floodplain is due to changes in the frequency of flooding events in the Midwest during recent decades. In the last ten years, the Upper Iowa River, which flows through Decorah, has experienced two major flooding events — first in 2008 and then in 2016.

Forrest Stewart (’20) I Chips
The dike between the Upper Iowa River and Luther’s practice fields currently serves as a barrier for the school.

“Flood risk has changed,” Peterson said. “What this [map update] is saying is that a dike of that size [used to] protect lower campus from this [100-year] flood, and now it doesn’t, meaning that that size of flood is happening more frequently.”

According to Peterson, there are various factors contributing to the increase in flooding frequency, including land use.

Land use refers to the way that landowners impact floodwater’s ability to absorb into the ground. As more land is converted into agricultural fields and developed areas with non-porous surfaces, floodwaters have fewer opportunities to discharge. Without these opportunities, more water remains in the river and flooding becomes more frequent.

Peterson said there are ways of combating these effects, especially in the context of agricultural land.

“There are a lot of options and the good news is that most of these options also provide some benefits to farmers,” Peterson said. “[One option is] buffer strips, putting perennial vegetation between the field of crops and a stream. These deep-rooted perennial grasses usually can help slow the flow of water across the surface and also make the soil more capable of absorbing water so that the water goes down into the soil instead of across the landscape into the stream.”

According to the Iowa Flood Center, an organization through the University of Iowa that helps people understand and be aware of flooding patterns, “conversion from agricultural to tall-grass prairie does not eliminate flooding, but would reduce its severity and frequency.”

Changing climate patterns are also a contributing factor to the expanding floodplain, according to Luther College Sustainability’s Zero Waste Educator Liam Fraser (’18).

“It’s unfortunate that we’re in a position where we need to raise the dikes,” Fraser said. “It means that the climate is changing and it’s having negative impacts on Decorah, Luther, [and] also communities downstream.”

Despite his concerns, Fraser added that he understands why the project is necessary.

“We have buildings, we have a dike in place,” Fraser said. “We have to make this investment.”

Currently, there is no set timetable for the project’s completion.

“We do not yet have that information. There are still the unknowns from the geo-technical evaluations that need to be resolved,” Runestad and Uthoff said. “If there are no complications, the project could move forward as soon as summer of 2018.”

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The student news site of Luther College in Decorah, Iowa