LAFAYETTE — The first updated flood map for Lafayette Parish since 1996 could be in effect before the end of the year, city-parish officials said Wednesday.

The new Federal Emergency Management Agency map, which is used to determine flood insurance rates and building elevations, is expected to shift the boundaries of some flood zones and classify large undeveloped tracts as floodways — a designation that can limit what can be built on the land.

“I’m sure some people will have heartburn, but I believe the maps will be accurate,” City-Parish Director of Public Works Tom Carroll said.

FEMA unveiled a preliminary flood map for the parish in 2007, but the changes had been on hold while city-parish government mounted an appeal that stretched for more than 3 years, challenging the process used to create the new map.

FEMA has agreed to some revisions, and the updated map is expected to soon be released to city-parish officials and could be in place before the end of the year, Carroll said.

The draft map released in 2007 sparked concern because several large tracts of undeveloped land were classified as being in a floodway.

Unlike normal flood zones, where development is generally allowed if structures are elevated to a certain height, floodways bring much tougher restrictions and can make some large developments nearly impossible.

Large swaths of land in the Scott area and areas along the Vermilion River in north Lafayette were labeled floodways, including undeveloped commercial property at the interchange of Louisiana Avenue and Interstate 10.

The revised maps are expected to still include substantial new floodway areas, but city-parish government was successful in taming some of the flood zone changes for an area in southern Lafayette Parish along Verot School Road, said Larry Broussard, an engineering supervisor with Public Works.

“It was a lot of give and take,” Broussard said of the FEMA appeals process.

About 90 percent of the flood designations in the draft map released in 2007 will remain in place, although there has been some fine-tuning throughout the parish, Carroll said.

Broussard said he thinks the give-and-take with FEMA has produced a much better flood map than the parish is now using, even if some residents might not want to see it.

“I think people might have always been in a flood plain but they didn’t know it,” Broussard said.

Beyond serving as a guide for flood insurance rates, the new FEMA flood map will also come with a high-tech digital model that can be used to gauge the effects that future developments might have on drainage and flooding, Carroll said.

He said engineers will be able to plug details about a proposed subdivision or shopping center into a computer model to determine how the new development will affect drainage in the surrounding area, offering ready answers to what might otherwise require an expensive engineering study.

Carroll said the computer model will also allow city-parish government to ask FEMA to adjust the new flood map if drainage improvements, such as dredging a coulee, lessen the risk of flooding to an area.

“It will be an ongoing process,” Carroll said.