The National Weather Service is completing a historical rainfall study, called Atlas 14. This study shows that Central Texas is more likely to experience larger storms than previously thought. This means that severe flooding is also more likely.
Changes to the 100-Year Storm
Before the study, we believed that in any given year, there was a 1 percent chance of 10.2 inches of rain falling in 24 hours in Austin. This was the official definition of the 100-year storm. The Atlas 14 study shows that this amount of rainfall is now likely to occur more frequently. The new 100-year storm will be closer to 13 inches of rain in some parts of Austin. This resembles the current 500-year storm. More information about Atlas 14 and the impacts to Austin.
Is Your Property in a Floodplain?
Maps of proposed floodplain changes are online. To view them:
Click the "I want to" button, then "Explore Atlas 14 Changes"
Enter your address and click on "Search."
Areas shown in blue are mapped within the 100-year floodplain currently. Purple areas indicate the interim 100-year floodplain, based on Atlas 14 and our new understanding of flood risk in Austin.
To print or download a map of your property, click the "I want to" button again and select "Print a Floodplain Map." Check the circle next to "Custom Map" and then the circle next to "Atlas 14." Choosing "Print Current" will prepare a map of the area you are currently zoomed in to.
What the City is Doing
We are proposing to change City code to address our new understanding of this increased flood risk. Currently many of our floodplain regulations are based on the 100-year flood. We are proposing to use the current 500-year flood for our regulations until floodplain maps can be redrawn. This change means that the current floodplain regulations will apply to more properties. Property owners and businesses in the 500-year floodplain would have new restrictions if they want to develop, expand, remodel or improve their properties.
There will be public meetings in September and public hearings about the code changes with the Environmental Commission, Planning Commission and the Austin City Council in the fall. Please leave us a message or send us an email with your comments or questions. Contact information can be found on the right-hand side of this page.