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Why Central Texas is known as ‘Flash Flood Alley’

We’re talking about how Austin earned the nickname Flash Flood Alley and became the Flash Flood Capital of the US.

A sign reading "Watch for Water on Road"

Austin lies in the heart of the Flash Flood Alley, which stretches from Dallas to Uvalde.

Photo by ATXtoday

When it rains in Austin, it pours, and sometimes it flash floods.

Austin sits in the heart of “Flash Flood Alley,” a stretch of land from Dallas to Uvalde that is very prone to rapid flooding and the flash flood capital of the US.

With some light rain in the forecast — and because October is one of the stormiest months of the year — we’re talking about how Flash Flood Alley got its name.

ATX_MansfieldDam

The Mansfield Dam was completed in 1941 to help alleviate downstream flooding.

Photo by shanntastic

Unique terrain + rainfall events

The combination of Central Texas’ hilly landscape, clay-rich and thin soil, and high rainfall intensity make the area susceptible to flooding — especially during a drought.

Although we Austinites like to bemoan the lack of rain, rapid intense rainfall (when we get it) can fall too fast for the soil to absorb it all, causing the water run to the nearest stream.

Of the six Highland Lakes — which includes Lakes Travis, Austin, and Lady Bird — only Lake Travis, via the Mansfield Dam, is designed to contain flood waters that flow downstream. Learn more abouthow the Highland Lakes System works.

Between June 2022 and June 2023, more than 300 flash flood events were recorded in Texas. Of them, 13 were in the Austin area. Major flash flooding in Austin happened as recently as last April, when rising water left 21 cars stranded in northwest Austin.

Stay safe during a flash flood

Like any other time it rains in Texas, avoid driving as much as you can. If you must drive, stick to higher ground, never attempt to drive on a flooded road, and observe all barricades. Just two feet of rushing water can carry cars away.

Follow ATXFloods for up-to-date information on flooding.