Austin Spent Millions Taking Them Out Of The Floodplain. A New Map Puts Them Back In.

Sep 26, 2018

A massive update to Austin’s floodplain map shows about 3,000 properties are at higher risk of flooding than previously thought. 

But a review of the map shows the new threat is most concentrated in some neighborhoods where the city has already spent millions to mitigate flood risk.

One of those places is the Las Cimas neighborhood, off Loyola Lane in East Austin.

“As soon as it used to rain ... no traffic could come in this area,” longtime resident Franklin Jackson says. “There was no way in. All the residents had to stay in until the water drained out.”

Before the Crystalbrook wall was built, Franklin Jackson says, no one could get in or out of the neighborhood during heavy rains because of flooding.
Credit Gabriel C. Pérez / KUT

His neighbor Noemi Everett remembers those days.

“Me and my kids used to push people out of the water,” she says.

In the early 2000s, the city improved drainage in Las Cimas. In 2004, it built the Crystalbrook flood wall on Walnut Creek, which runs along the neighborhood.

The price tag was around $15 million, and neighbors say it was worth it.

“It’s become a very boring, dry neighborhood,” Everett laughs.

According to city documents, the project allowed 175 houses to be removed from the 100-year floodplain, a high-flood-risk area where there are extra permitting and building requirements.

The Crystalbrook flood wall also freed Las Cimas residents from having to buy flood insurance.

Before the wall went up, insurance cost about $500 a year, Everett says, “a lot for those of us that don’t make that much money.”

But now, Austin officials say she should consider getting insured again: 14 years after the wall was built, the properties in Las Cimas are going back in the floodplain.

“It all ties back to the new rainfall data,” says Pam Kearfott, the engineer in charge of creek flooding for Austin’s Watershed Protection Department.

Kearfott is referring to a new National Weather Service study called Atlas 14, which added about a quarter-century worth of rainfall data to local weather models. That data showed heavier rains around Austin are more common than previously thought.

For Las Cimas residents, that means rainfall assumptions considered when building the wall were wrong.

“The walls were designed for this 100-year flood level,” Kearfott says. “What we know through Atlas 14 ... is that we are slightly more likely to have a rainfall event of that size to cause that flood wall to overtop.”

The impacts of Atlas 14 go well beyond Las Cimas. In the Southeast neighborhood of Dove Springs, hundreds of homes near the $8 million Creek Bend flood wall are also back in the floodplain. And other parts of town that are not near flood walls or creeks are also impacted.

A city website shows residents what their new risk is. Kearfott says the map will be revised in two years – but folks shouldn't assume that update will bring any good news.

She says those who live in newly designated floodplains should "talk to their insurance agents and consider flood insurance.”

Everett says she probably won’t get insurance again. After all, the flood wall’s been working since the city put it up 14 years ago.

“If I was concerned about flooding here, I’d definitely have it," she says, "but I’m not concerned at all about it."

Experts say she should be.

City officials say the flood walls have worked well in storms so far, but eventually a rain will come to overtop them – and the new map shows that storm may come sooner than we thought.

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