The City of Charleston is a community participant in the National Flood Insurance Program (NFIP) and Community Rating System (CRS). Our participation in these programs helps to reduce the risk of current and future flooding, resulting in a more resilient community.”
Flood design elevation increase: Effective July 1st, 2020, all residential & non-residential new construction, and non-residential substantial improvements, in the Special Flood Hazard Area (SFHA) must be designed 2 ft. above Base Flood Elevation (BFE).Residential substantial improvement will remain at 1 ft. above BFE.
Ordinance to Prohibit Slab-on-Grade Foundations (building diagrams 1A, 1B, 2A, and 3) in the SFHA or 100-year Floodplain will become effective for projects applied on or after January 1, 2024
The amendment to the City's Stormwater Ordinance was passed on April 11, 2023with support from Charleston Trident Association of Realtors, the Coastal Conservation League, Charleston Homebuilders, the Southern Environmental Law Center and the Historic Charleston Foundation, as well as City staff and members of City Council.
Fill is used to elevate large portions of development sites, as such, slab-on-grade foundations can be used for new or redeveloped home residential construction.
Large quantities of fill can alter drainage sites, may lessen rainfall infiltration, accelerate runoff and/or displace water onto neighboring properties and downstream communities.
(Image credit: Lincoln Co. WI, Land Services)
To promote, where practical, the natural functions of the floodplain
To reduce loss of life and reduce damage to property from flooding
To mitigate damage to structures in the Special Flood Hazard Area (SFHA) from flood events
Promote, manage, and enforce Federal Emergency Management Agency (FEMA) requirements and recommendations
Promote, manage, and enforce National Flood Insurance Program (NFIP) requirements and recommendations
Promote, manage, and expand participation in the NFIP’s Community Rating System (CRS)
Manage and make available Flood Insurance Rate Map (FIRM) information
Manage development within the Special Flood Hazard Area (SFHA)
Natural and Beneficial Floodplain Functions:
The natural functions of floodplains, when preserved or restored to their undeveloped state, provide a range of benefits to both natural and human systems. These benefits fall into the following categories:
Provides floodwater storage and conveyance which reduces the severity of floods or storm surge
Allows sediment to settle out of stormwater, attenuates excess nutrients, and supports other qualities managed under the community’s National Pollutant Discharge Elimination System (NPDES) permit
Allows groundwater recharge
Provides habitat for feeding and reproduction for fish and wildlife species
Support high rates of biologic production and diversity
Riparian and coastal vegetation helps stabilize river banks and beaches against erosion
Agricultural and wildlife harvesting, including shellfish harvesting
Recreational and aesthetic enjoyment
Spaces which provide natural and beneficial floodplain functions in the Charleston area include salt marsh, intertidal wetlands, coastal barriers (such as dunes and maritime forest), and forested wetlands. Regulating development in these sensitive areas helps to preserve their community benefit.