The Onion Creek Flood Study has two main goals: to update the floodplain maps for Onion Creek and to evaluate options to reduce flooding in the Onion Creek Neighborhood.

For more information about the floodplain maps, please keep reading. For information about reducing the risk of flooding, visit the Upper Onion Creek Flood Risk Reduction Project web page.

The current floodplain maps for Onion Creek are based on data from the 1980s. The floodplain study updates the data for more accurate floodplain maps.

Study Location

Onion Creek is Austin’s largest watershed. In fact, most of the watershed is outside of Austin in Hays County. The floodplain study focuses on the part of Onion Creek within Austin and Travis County. It also looks at three of the creeks that feed Onion Creek: Bear, Little Bear and Rinard.

Proposed Updates to Floodplain Maps

Use the map above to view the proposed updates to the Onion Creek floodplain maps or click here for a larger version of the map.


The City of Austin began using the updated maps for regulatory purposes in January 2017. New FEMA floodplain maps, used to administer flood insurance, will become effective on January 22, 2020.

FEMA has an established process to update floodplain maps. There is more information at

More Info

Questions? Please leave a message at 512-974-2843 and a staff member will call you back or send an email. To sign up for email updates, please email Stephanie Lott.