Iowa City Council approves changes to flood plain rules, wording

IOWA CITY - Many construction projects in Iowa City will now have to be above the 500-year flood level, except it won't be called that.

The City Council voted 7-0 Tuesday night to adopt changes to the city's flood plain ordinance.

It had been written to meet the risks of a 100-year flood. New and substantially improved structures now must be elevated at least one foot above the 500-year flood levels. Commercial buildings can be elevated or floodproofed.

Also, the city is doing away with the terms “100-year” and “500-year” floods, saying they are misleading. 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.

The city will use those percentages when referring to those levels of flooding and will call those flood boundaries a “flood hazard area.”