Why does it flood?
We live in a region known as Flash Flood Alley. It stretches from Del Rio in southwest Texas, east to San Antonio and follows the IH-35 corridor north through the Dallas-Fort Worth metroplex. Heavy rainfall and drainage off this landscape, also known as the Balcones Escarpment, combine to make this part of Texas one of the most flood-prone regions in North America.
In the San Antonio River Basin of South Texas, steep terrain, shallow soils, and narrow river channels send runoff quickly downhill. The result is deep, fast, and erosive flood waters. These destructive forces have the potential to penetrate communities downstream, threatening lives and property throughout the basin.
The San Antonio River Authority is meeting the challenge head-on with a multi-level approach to flood risk management.
Hover or touch the map below to view the counties in Texas that are part of "Flash Flood Alley."