Study: Apartments worsened flooding in San Marcos neighborhood

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San Marcos City Council members cited a “moral obligation” to assist those whose homes received elevated water levels during the Memorial Day weekend flooding as a result of the Woods apartments.

The Woods apartments, located near I-35 and River Road, caused as much as 2.3 feet of additional water to enter homes along River Road, according to a study by Halff & Associates.

“The questions is what do we do now?” Council Member John Thomaides said. “Where do we go from here? Now that we know what’s happened here, what going to happen again, I think clearly the Woods apartment complex has got to step up to do something. I don’t know what yet. They clearly in my opinion exacerbated the flooding in that neighborhood.”

The findings of the study reversed those of an earlier analysis presented to City Council in September. At that time, Halff & Associates representative Michael Moya said the Woods had little or no effect on flooding in Blanco Gardens.

The analysis Moya presented to City Council Jan. 5 used a 2-dimensional model to map how water moved through the city during the May flood event. The previous study was a 1-dimensional analysis, which did not use high water marks or rates of flow on the San Marcos and Blanco rivers.

The 2-dimensional analysis used 200,000 data points to provide what he called a more robust analysis of what occurred during the Memorial Day weekend flood.

Thomaides asked why the city received a presentation of the 1-D model in the first place. Thomaides asked Moya why he was so confident at the time he presented the 1-D study. Moya said the 1-D model was based off the best available data at that time.

“With the tools that we had at the time, I believed there was no impact based on the model we had,” Moya said. “We felt confident given those tools we had at our disposal that there was no impact.”

According to the analysis, the severity of the Woods’ impact on flooding lessened further north of River Road, away from the apartments. According to a map Moya showed during the presentation, houses north of Clair Drive did not take on any additional water as a result of the apartments. Council Member Lisa Prewitt said she was skeptical of that and wanted to make sure the analysis was correct.

“We’re going to have to make huge decisions about developing in that neighborhood, leaving development as it is, doing buyouts in that neighborhood, and this is huge,” Prewitt said. “If you’re telling us from Clair on back that [the apartments]had nothing to do with [additional flooding], that’s going to be a huge conversation, so let’s make sure this data is totally perfectly correct.”

With a more definitive study than the 1-D analysis now indicating the Woods did effect the severity of flooding, the city will turn its attention to how to prevent similar issues in the future. Council Member Melissa Derrick suggested the Woods may be able to pay to have drainage on its property improved, citing a similar instance in Tuscaloosa, Georgia, when the same developer of the Woods, Dovetail Companies, built an apartment project that flooded a neighborhood. In that case the developers worked with the city to add additional drainage on their property, she said.

Council Member Scott Gregson said he wants to see how the process of approval happened in the first place and find ways to improve that process.

Moya said the city could make a few short-term, relatively inexpensive adjustments that would help the Blanco Gardens neighborhood and the area near the Wood apartments better withstand typical floods. To mitigate future damage during larger storms like the Memorial Day weekend flood or a 100-year flood, the options get more expensive.

“If you want to look at something like the May event or the 100-year [flood], you’re looking at substantial improvements like levies,” he said.

City Council will hold a workshop in the next two months to discuss potential changes to the city’s land development code that would further regulate developments within the floodplain. Potential changes include increasing the elevation at which residential structures must be built—from 1 foot above the 1-percent flood level to 2 feet above that level—and clarifying existing language in the code.

“This year is devoted to coming up with a permanent solution, a fix-it-forever solution, for this area,” Thomaides said. “It’s big, and it’s expensive, and it’s not going to happen tomorrow. But we’re starting on it right now and we’ll continue on it through the month.”

The map presented during the Jan. 5 City Council meeting shows the effect the Woods would have on Blanco Gardens during a flood event similar to the Memorial Day weekend flood.

The map presented during the Jan. 5 City Council meeting shows the effect the Woods would have on Blanco Gardens during a flood event similar to the Memorial Day weekend flood. (via Halff & Associates)

This map, presented during the Jan. 5 City Council meeting, shows the actual effect the Woods had on Blanco Gardens during the Memorial Day weekend flood. The apartments were still under construction at that time and large dirt mounds blocked some drainage features in the complex.

This map, presented during the Jan. 5 City Council meeting, shows the actual effect the Woods had on Blanco Gardens during the Memorial Day weekend flood. The apartments were still under construction at that time and large dirt mounds blocked some drainage features in the complex. (via Halff & Associates)

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COMMENT
  1. Sherry Francis

    There is no way the city engineers didn’t know this would happen. Looks like a plan to buy out and sell to apartment complex builders. The whole city of engineers need to be fired. This was not something that should have happened.

  2. In response to Sherry Francis:
    The waters in this flood rose above the levels predicted for a 500 year flood. In other words, the likelihood of this type of flood is expected to occur once, only every 500 to 1000 years.
    Of course, the city engineers knew that houses would be flooded during a 500-1000 year flood. Everyone knows and expects damage to occur in residential neighborhoods during a flood of this magnitude.
    Also, engineers are responsible for different things. Some design buildings, some roads, some the water treatment facility, others determine floodplains and the effects buildings will have on water flow. However, to say that all of the city engineers should be fired when most are not involved in flood analysis is a very strange thing to say.

  3. The neighborhood behind LA Quinta and the new storage building should be looked as well. Never been flooded before these went up. Terrible.

Brett Thorne reported on education, business, economic development and city government in San Marcos, Kyle and Buda from 2012 to 2017. Thorne attended Texas State University in San Marcos, where he graduated in 2010. He joined Community Impact Newspaper as a reporter in 2012 and was promoted to editor in 2013.
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