Sinking Houston suburbs: How groundwater extraction is causing neighborhoods to sink

BAYTOWN, Texas (KTRK) -- You have to know where to look, but signs of the old Brownwood subdivision still exist at the present-day Baytown Nature Center.

There are old remnants of roads and driveways, an old bathroom floor and even an exposed pool that was once below ground.

"This was actually referred to as the River Oaks of Baytown," Christina Butcher, who is a naturalist at the Baytown Nature Center, said. "This was a neighborhood that had oil executives, doctors and lawyers, upper-middle class families."

The neighborhood, which was built in the late 1930s, received its knockout punch courtesy of Hurricane Alicia in 1983, but years of sinking are what led to the subdivision's ultimate demise.

"Baytown experienced a population boom, and until 1976, the City of Baytown got its water from the ground," Butcher explained. "When you're pumping out groundwater, and you have a population boom, that caused the land to subside."

The National Oceanic and Atmospheric Administration defines subsidence as "the sinking of ground because of underground material movement," and experts emphasize the story of Brownwood is an extreme example of the effects subsidence can have on a community.

"We're still studying it today," Butcher said on subsidence and the impact it had on Brownwood.

In fact, the University of Houston released a survey in August examining subsidence across the Houston area from May 2016 through December 2020.

"I got to the University of Houston in 2003, and we saw this problem," geology professor Dr. Shubab Khan said.

A member of Khan's team said their work used cutting-edge technology to investigate subsidence in the area at "unprecedented detail."

"What we are doing is we are using all these new tools," Khan said. "We did this for a larger area - Harris and all surrounding counties.

It found large parts of Katy, Spring, Fresno, Channelview, and Mont Belvieu experienced subsidence anywhere from about three to nine centimeters over that four-year timespan. The Woodlands also saw sinking at that level, but not as widespread.

Overall, the study found an average subsidence rate of about two centimeters a year for communities who experienced sinking.

"Subsidence exacerbates flooding," San Jacinto River Authority General Manager Jace Houston said. "We're already in a low-lying flat coastal area, so if you begin to lower areas that are susceptible to periodic flooding, that's dangerous."

The San Jacinto River Authority provides water to areas like Conroe and The Woodlands.

They say their yearly goal is to get half of their water from underground, and the other half from sources such as lakes and rivers - or surface water.

The study done by UH found that most subsidence in the area resulted from overreliance on groundwater, with areas like Mont Belvieu experiencing more subsidence due to oil-and-gas extraction.

"When you see subsidence, we know what it's caused by," Houston said. "It's caused by pumping too much groundwater too quickly in that area."

On the contrary, Dr. Khan's study showed areas like Spring Branch, as well as places around downtown Houston, have been able to slow subsidence down to nearly non-existent levels over the years by regulating the use of groundwater and resorting to more surface water.

The survey found most examples of subsidence took place in suburbs outside of the City of Houston.

"Since (1975), where regulations by the Subsidence District have been in place now for decades, those are areas that are now stable," said Harris-Galveston Subsidence District General Manager Mike Turco. "Subsidence rates are down near zero."

It's an issue everyone involved in this story will continue to tackle, as population growth and the soil in Southeast Texas mean subsidence is a constant threat to this area.

A threat they know all too well at the Baytown Nature Center.

"This is a very unique situation," Butcher said about the neighborhood where she spent her earliest years. "We've learned from it."

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