Austin and other communities within Upper Brushy Creek Water Control and Improvement District have updated the floodplain maps for Upper Brusy Creek, including portions of Lake, Rattan and South Brushy Creeks.

Updates to Floodplain Maps

Map and link to online floodplain viewer

Click on the map above to view the changes to the floodplain maps. To download a pdf or data from the study, go to this FEMA Map Service Center web site and select Texas and Williamson County from the drop-down menus.

Use of Floodplain Maps

Floodplain maps indicate which areas are likely to flood when a creek overflows its banks. The maps are used to help plan and prepare for floods. FEMA uses them to administer the National Flood Insurance Program.

Austin maintains a second set of floodplain maps that are slightly different than the ones FEMA issues and uses. Austin’s floodplain maps are based on the assumption of increased development in the future, called fully-developed conditions. Austin uses these floodplain maps to regulate development and to issue permits for building and remodeling. Find out more about floodplain regulations.

Both the FEMA and City of Austin floodplain maps were updated by this study.


  • 2017 – FEMA release of preliminary maps for internal review by impacted communities. The City of Austin begins to use the maps for regulatory purposes.
  • February 2018 to May 2018 –  Preliminary maps made available to the public for appeals and comments.
  • Summer 2018 to Spring 2019 – Appeals and comments were resolved.
  • December 20, 2019 – Maps became effective for flood insurance purposes.