Ongoing processes to map areas in the county at risk of flooding could change the way homes and businesses are built in Hays County.

But high costs and other restrictive factors associated with raising new structures’ elevation standards to reduce flood risk will be considered as regional leaders weigh how to respond to the Memorial Day and Halloween floods of 2015.

San Marcos

Recent storms could bring about regulatory change in San Marcos, where proposed city code updates include language that states that data sources for regulating the flood plain can include the best available information and not just Federal Emergency Management Agency maps and models, which may not be the most current information. For example, the city could utilize information from independent studies or Hays County’s flood-risk study.

City Council will hold a workshop in  February or March to discuss potential changes to the city’s land development code, including clarifying language in the code and 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.

Flooding in May damaged 509 San Marcos properties. Ninety-two properties were destroyed in the event. By contrast, 195 San Marcos properties were damaged in the October event, and no properties were destroyed, according to the city of San Marcos.

Kyle

Most city buildings are designed to withstand a 100-year flood event, which has a 1 percent chance of occurring in any given year.

But regulating development to design to a higher standard—such as 250- or 500-year floods, which respectively have a 0.4 and a 0.2 percent chance of happening in a given year—is costly and would render a lot of developable land unbuildable, City Planning Director Howard Koontz said.

“It’s a balance between what you expect to happen in a rain event versus how much of a property somebody should be able to build on, use or enjoy,” Koontz said.

Mario Perez, who heads the city’s building department, said he may put forward in 2016 a proposal to add a section to the city’s ordinance on flood prevention, which would give the city the ability to raise the minimum elevation for building structures in special flood hazard areas higher than the base flood elevation. Perez said any new height specifications would apply to new construction or substantial improvements.

The ordinance currently stipulates structures must be built at or above the base flood elevation.

Buda

In the midst of a rewrite of its unified development code, the city of Buda is examining whether to increase flood-prevention standards as well, City Planning Director Chance Sparks said. Adoption of the code revision is expected to go to Buda City Council for review in early 2016.

The city is also in the design phase of building new municipal facilities as part of a $55 million bond program approved by voters in 2014. The co-located police department facility, public library and City Hall could be built to withstand a natural event greater than a 100-year flood.

ECM International, the administrator of the bond program, is examining whether to use methods such as underground ditching to guard against severe flooding.

“I think it would just be irresponsible of us to build a new structure and not consider events that are going to happen with the lifetime of that structure,” Council Member Angela Kennedy said, adding council should “push for drainage that would hold the worst event that we have seen.”

Hays County

Clint Garza, Hays County director of development services, said new data—in the form of advisory maps developed by FEMA and maps drawn as part of the county’s own flood-risk study—will help regulators and developers decide how to avoid putting structures and people in harm’s way.

Because new development often alters the way water drains during a flood high-growth areas such as Hays County often take priority over areas that are not experiencing population change.

Preliminary flood-risk maps from FEMA, which will be the first official revision to area flood maps since 2005, are expected to be made public in November. After stakeholder engagement and public forums to discuss the revised maps, the new maps could be up for adoption in mid-2017, according to a FEMA presentation.

Garza said Hays County uses newer but unofficial advisory maps from FEMA to provide information to developers even though the data from those maps are not reflected in the county’s official regulatory maps.

But he acknowledged that in events such as the Memorial Day and Halloween floods of 2015, it is almost impossible to avoid some degree of destruction.

“Even a map update isn’t going to prepare someone for that kind of event,” Garza said.