SAN ANTONIO — Erin Cavazos oversees a lot as the San Antonio River Authority’s engineer manager. 

 “So the San Antonio River Authority has the four-county jurisdiction — Bexar, Wilson, Karnes and Goliad counties, and we work to have clean, safe and enjoyable rivers and creeks,” Cavazos said. 

Right now, the River Authority is updating the flood maps for the four counties. 

“All that data and synthesize it to understand when it rains, how much of that goes into the creeks,” Cavazos said. “How deep does it flood? It involves a lot of modeling and engineering analysis.” 

The flood map is still a draft, but so far it’s bad news for some people in San Antonio — 1,900 more structures were added to the floodplain. All in this neighborhood in San Antonio’s Southwest side. That means if a 100-year-flood event were to happen, those structures, including homes, would experience severe flooding. 

In response to a drafted flood map, the City of San Antonio is planning to fix infrastructure — tunnels, drainage and creeks. 

Once the maps are finalized, as many as 158 homeowners could be forced to relocate 

Cavazos says Bexar County-area maps are expected to be finalized within the next 36 months. Other Texas counties are in different phases, but are working to get their flood maps updated soon.  

“In 2018 the National Weather Service, NOAA, released updated precipitation data for Texas and that sparked a lot of movement statewide,” Cavazos said. 

The NOAA report showed floods once categorized as 100-year floods were actually happening more like every 25 years.

The precipitation totals were updated. Cavazos says those clarified totals were a wakeup call to how bad a major flood could be.

“In the flooding, it has a depth, it has an elevation that it’s hitting on the ground, so if you are above the ground, every inch above the ground is going to reduce the risk,” Cavazos said. 

It’s estimated that there’s a 1 percent chance a 100-year-flood can happen in any given year.  

“When we look at that over a 30-year period, that turns into a 97% chance, especially when we are considering in the floodplain. There are areas that are greater risk,” Cavazos said.