Floodplain Information

Flooding can occur anywhere.  Alpharetta is susceptible to flash floods where streams and creeks can rise quickly out of their banks.  Because many of  our streams start outside of the city limits, we can experience flooding even if it is not raining in Alpharetta.  Please follow all warning signs in the event of a flood. Do not drive through standing or rushing water.  Water may be deeper than it appears and can hide many hazards (i.e. sharp objects, washed out road surfaces, electrical wires, chemicals, etc.).  Each year more deaths occur due to flooding than from any other thunderstorm related hazard.  Over half of all flood-related drownings occur when a vehicle is driven into hazardous flood water.  Six inches of fast-moving water can knock over an adult.  As little as twelve inches of rushing water can carry away a car. 


The Georgia Department of Natural Resources (GA DNR) and the Federal Emergency Management Agency (FEMA), in conjunction with the City, updated the FEMA maps in 2013.  Copies of the new maps and flood insurance information can be found below.

In accordance with the City’s National Pollutant Discharge Elimination System (NPDES), Municipal Separate Storm System (MS4), and the Permit with the Georgia Department of Natural Resources Environmental Protection Division, the City is required to regulate development in expanded Special Flood hazard Areas and Future Floodplains.  The expanded Special Flood Hazard Areas are based on drainage basins of 100-640 acres at current land use conditions.  The Future floodplains are estimated flood elevations considering land use fully built out per the comprehensive plan.  Regulations for development can be found in the Unified Development Code Article III Section 3.4.  City floodplain maps can be accessed through the link below.

If you have questions for the City, please call 678-297-6200.



FEMA Floodplain Maps  

City Floodplain Maps

How to make a FIRMette  

Flood Insurance Information  

GA DNR Flood Map Website  

FEMA Letter of Map Amendment & Revision  

FEMA Elevation Certificate & Instructions  

No Adverse Impact – NAI 
Flood Inundation Map for Big Creek

Flood Inundation Map Report for Big Creek