GONZALES — The owners of more than 1,200 properties in southern Ascension Parish could see lower flood insurance rates after the adoption of new FEMA flood maps, though 340 other properties in the same area could be tagged with higher risk ratings.

Parish officials will hold a community meeting Thursday to explain what will change following a lengthy look at the flood threat. To see the maps, go to https://msc.fema.gov/portal/availabilitySearch?addcommunity=220015&communityName=GONZALES,%20CITY%20OF#searchresultsanchor and look under the categories of “Pending Product, LOMC, LOMR.”

Parish officials have sent letters to property owners or household occupants whose homes or land will move into a higher risk flood zone. Joey Tureau, the parish's chief engineer, told the East Ascension drainage board Monday night that residents who are on the edge of areas being designated a higher risk are being notified as well.

"Those people, if they haven't gotten letters, should be getting them very shortly," Tureau said.   

For the past several months, parish drainage officials have discussed the need to notify property owners impacted by the change so they will have an opportunity to obtain flood insurance at a lower cost before the rate map changes take effect on May 15.

"Once the changes go into effect, that opportunity ends," a parish statement says. 

The Flood Insurance Rate Map designates the areas deemed most at risk of flooding and, as a result, will require flood insurance for homeowners with mortgages.

Last year, Ascension Parish, through its East Ascension drainage board, completed a detailed look at the Panama Canal, Boyle Bayou and Bayou Conway watersheds. They encompass Sorrento and other areas south of Gonzales, including Pelican Point, Pelican Crossing, Ascension Trace, Conway and other subdivisions south of Interstate 10.

The study's results were included in a subsequent request to the Federal Emergency Management Agency to alter insurance flood maps for the region. Older maps did not always establish a height for the base flood elevation. That elevation is the projected height of floodwater in a 100-year-flood, which is better described as a flood that has a 1 percent chance of happening in any year.

Homes with bottom floors below this height, known as the "BFE," and also the subject of a bank mortgage must have flood insurance.

In Ascension, as in East Baton Rouge Parish, new homes must be built 1 foot above the BFE, an elevation that varies depending on the location. 

A listing of the affected addresses wasn't immediately available, but the proposed maps show some large-scale changes.

Under the old maps, the northern halves of the Pelican Point and Pelican Crossing subdivisions along La. 44 fell into an area deemed to be in a high-risk zone requiring flood insurance, but with no base flood elevations set to show what height would be necessary to raise a home out of the risk area.

The proposed maps show those same sections of the subdivisions are now largely in a zone deemed at moderate flood risk that doesn't require flood insurance.  

Parish Councilman Bill Dawson, who represents the Pelican Point area and had pushed for the analysis a few years ago now leading to the map changes, said residents now found to be in the lower-risk areas could be in line for flood insurance reductions. 

Tureau told Dawson letters to those property owners had not gone out yet.

"We just wanted to send the ones to those adversely affected because meeting that May 15th deadline was very important for them if they wanted to take any action," Tureau said. "So that's why we jumped on that pretty early."  

In addition to establishing base flood elevations in parts of Ascension, the maps also established floodways for the first time. Deemed part of the primary flow channel for the parish's myriad bayous and canals, FEMA applies enhanced restrictions in floodways that greatly limit new construction.

Residents in the floodway have also been sent letters from the parish, Tureau said.

Thursday's meeting will be held from 5 to 6 p.m. at the Ascension Parish Governmental Complex, 615 E. Worthey St. in Gonzales.

Follow David J. Mitchell on Twitter, @NewsieDave.