Flash Flood Alley Segements

San Antonio, Texas "One of the most flood-prone regions in North America"

San Antonio River Authority

San Antonio River Authority (SARA) ---->Watershed Map
San Antonio is a populated area in one of the most flash-flood prone regions in North America. SARA manages a series of structural controls (dams and drainage systems) to help prevent and/or reduce flood problems. For example, the San Antonio River Tunnels (see illustration) proved invaluable as they diverted water safely underneath downtown during the 1998 and 2002 floods.

Read more About SARA (PDF document)

Read more about Bexar Regional Watershed Management program (BRWM) (PDF document)

Soon to be live: www.bexarwatershed.org

See the San Antonio Area's Historic Streamflow Data

Flood tunnel
Tunnel Full Size

Compare the 1998
and 2002 storms

Be Careful

San Antonio Fire Cheif

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San Antonio's Fire Chief has a message about low-water crossings.


The majority of flood-related deaths are caused by people attempting to drive through moving water. This interactive segment explains the most common ways people die in these situations.
See this Interactive Segment

Flood Interactive


Flash Flood Alley - Interactive

Flash flood Alley Interactive


Texas is prone to extremely heavy rains and flooding with half of the world record rainfall rates (48 hours or less). Central Texas (known as Flash Flood Alley) is particularly vulnerable because storms stall out along the Balcones escarpment. read more >

Links to historical photos of floods in the San Antonio region:

Flood Photos

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San Antonio River Authority Flood Control Structures

San Antonio Flood Tunnel Cut-Away
Olmos Dam
Smaller Retention Dams:Salado Martinez Calaveras
Salado Dam Explained

An explanation of the effects of impervious cover on flooding -- by the San Antonio Express News.