Floodplain maps help identify where flooding is likely to occur and help us prepare for and communicate the risks of flooding. Floodplain maps are also used to regulate development and for flood insurance purposes.

We periodically update our maps to reflect changing conditions and improved technology and data. To update a floodplain map for one of Austin’s creeks, we study the whole watershed draining to that creek. Such a study is called a floodplain study. It typically takes a few years from the start of the floodplain study until new floodplain maps are issued by FEMA.

Status of Floodplain Studies

We have begun the process to update floodplains citywide as a result of the Atlas 14 study. This study found that Austin is at increased risk for flooding due to heavier rainfall rates. There is more information about this floodplain remapping effort at ATXFloodplains.com.

Appeals and Comments

Before new floodplain maps become effective, there is a 90-day public appeal and comment period. Comments are intended to correct small issues such as mislabeled streets. Appeals must be based on engineering analysis. 

Flood Insurance in Newly-Mapped Areas

Mortgage companies usually require flood insurance for homes and businesses in the floodplain. There is a Newly Mapped Policy available for the first year when there are changes to floodplain maps. Download this FEMA document for more information: Policies for Buildings Newly Mapped into a High-Risk Area (pdf).

Video about Floodplain Changes


Process for a Floodplain Study

The City of Austin works closely with FEMA to revise floodplain maps when such revisions are necessary. There is a formal process to revise a FEMA floodplain map. You can expect to see the following steps:

  • Engineering study that includes surveying, data collection, floodplain modeling and mapping.
  • New floodplains used for City of Austin development regulation.
  • Submittal of the study to FEMA as a Letter of Map Revision.
  • Initiation of a Physical Map Revision (PMR) by FEMA to update the FEMA FIRM maps.
    • Preliminary maps available for public review
    • 90-day public appeal and comment period
    • Letter of Final Determination issued by FEMA to the City of Austin and other affected counties, cities and towns
    • Map effective date (six months after Letter of Final Determination)

Current Floodplain Maps