Iowa City considers new construction rules for floodplains

New construction and structures undergoing significant renovations in floodplains would face stricter standards under provisions being considered by the city of Iowa City.

City staff is proposing that the standards and requirements in the city's flood ordinance, which currently are written to meet the risks of a 100-year flood, be increased to 500-year-flood levels. The 2008 flood reached the 500-year boundaries in Iowa City.

New construction occurring in a floodplain would need to be elevated at least one foot above the 500-year-flood elevation. Commercial buildings would have to be elevated or flood-proofed.

Existing structures that are to be expanded by more than 25 percent of their original floor area or undergo renovations in excess of 50 percent of their assessed value also would have to meet the new standards.

Depending on the location in Iowa City, this would require an additional elevation of between a couple of inches to a couple of feet, according to the city.

The city's Planning and Zoning Commission will discuss the proposals at its June 17 meeting. The city is seeking feedback, and comments can be e-mailed to julie-tallman@iowa-city.org or bob-miklo@iowa-city.org.

The City Council would have the final say on any changes.

Julie Tallman, the city's development regulation specialist, said the changes would make some construction projects more expensive, and she expects objections. But she pointed to the millions of dollars in damage caused by the 2008 flood as a reason to increase the standards to reduce the risk in future floods.

“The state of Iowa can't afford to keep responding to these disasters,” she said.

The standards came out of a committee organized by the Legislature, she said, and the city of Cedar Falls recently adopted similar changes.

City staff also say that the terms “100-year floodplain” and “500-year floodplain” are often misunderstood and want them replaced with “flood hazard area” in the city's zoning ordinance. A 100-year flood has a 1 percent chance of occurring in any given year, and a 500-flood has a 0.2 percent chance.

More details are available at

www.icgov.org/boardagenda/2181.pdf.