Updated Flood Zones for Charleston County

At long last and with much anticipation, the Lowcountry has updated a substantial portion of its flood zone maps. 

During nearly five years of review, the process understandably became a bit complicated as a number of agencies – FEMA, Charleston County, and the state’s SC Department of Natural Resources – analyzed mountains of data from flood-prone areas to assess actual risks, sometimes parcel by parcel. 

The purpose of these maps is to provide accurate guidance to insurance providers and building permit offices, and whose ultimate effect on homeowners is a twofold: a better assessment of flood risk for the property, as well as improved data for insurance companies to issue flood policies.

A Better Model for Flood Zones

Charleston County has been operating with flood zone maps that were last updated in 2004, and while these maps needed an update to reflect new data and sea level rise, they were also based on a flawed model of determining flood risk.

The primary determinations of flood zones in the current maps are based on storm surge predictions during a Category 3 hurricane, and while that certainly seems prudent we all know that flooding can also occur during non-tropical rainfall events.

Street flooding in downtown Charleston

More often than not, assessing the flood risks for a home in the Lowcountry is predictable and sane.

Though most homes are constructed to accommodate our subtropical climate, we have witnessed some unsettling events that a smart homebuyer should strive to avoid. 

Some established neighborhoods, despite their modest flood risk, tragically endured substantial water damage in some of their homes.
A smart homebuyer would scrutinize certain areas to understand the history and infrastructure regarding stormwater control. 

Updated flood zone maps will be based not only on storm surge data but also on flooding that results from rainfall accumulation and tidal forces. 

Also, inaccuracies in the storm surge estimates have been improved with data from recent tropical storms, and that data has been incorporated into the maps to adjust the flood zone elevations.

Assessing the Risk

An aerial view of homes on South Battery Street in CharlestonThe new flood zone maps that take effect in January 2021 will impact tens of thousands of properties in Charleston County.

Most assuredly, there are some homes previously listed as low risk that will now be escalated.
However most of the properties in Charleston County with adjusted flood zone designations will be deemed lower risk than on current maps – many of which have been required to carry flood insurance despite having never experienced flooding.

Cumulatively, this means that not only will flood insurance rates be more reflective of actual risk, but also home buyers will be able to assess the potential flooding threats to their home with greater confidence.

Some homes will be subject to higher flood insurance rates while many, many others will see relief from them.

For a deeper dive into how flood insurance works, and assessing the risk when buying a home in Charleston, visit my Flood Insurance Guide.