Houston’s pocket prairies: Natural solutions to unnatural flooding

Deep in the heart of the dense steel and glass jungle of Houston’s Medical Center district, you can catch glimpses of what the city looked like some 400 years ago. 

Tall grasses rise up from one corner, sheltering more than 70 different plant and flower species. It looks messy, swampy, and wild – especially compared to the pristine grass lawns that surround many Houston buildings. It looks like coastal prairie.

Prairie like this covered coastal Texas and Louisiana for centuries, stretching from modern-day New Orleans all the way to Corpus Christi. Covering 9 million acres and supporting iconic flora and fauna like bluebonnets, monarch butterflies, and longhorn cattle, it evolved to survive, and thrive, in a corner of the world subject to both frequent flooding and drought. 

The prairie couldn’t survive the growth of cities and agriculture, however, and today less than 1% of the original coastal ecosystem remains. But as the region has experienced four “500 year” rain events in the past five years – including this month’s Tropical Storm Imelda – a prairie renaissance has been blossoming in Houston. 

“Prairies are a completely different way of thinking,” says Jim Blackburn, professor of environmental law at Rice University in Houston. “We tend to be biased towards technological solutions and engineering solutions rather than natural solutions. We don’t think of nature solving our problems.”

But that’s starting to change in Houston, where local officials, conservation groups, and even developers have been talking up prairies and their benefits, from detaining and filtering stormwater, to nourishing wildlife, sequestering carbon, and improving mental health. More than 50 miniaturized “pocket prairies” have been planted around the Houston metro area since 2008.

“That alone is not the answer,” says Professor Blackburn, who also co-directs the center on severe storm prediction, education, and evacuation from disasters at Rice. “But I think it’s part of a long-term solution.”

“A touchy subject”

While pocket prairies effectively mirror the pre-settlement Houston landscape, in many ways they are pale imitations – prairies manicured and airbrushed for the modern age.

Some 20 miles east of the Medical Center, in the suburb of Deer Park, is the real thing. The 51-acre Deer Park Prairie, home to more than 400 species of plants, is “pristine” – never farmed, developed, or touched by humans in any way, according to Della Barbato, director of education at the Native Prairies Association of Texas (NPAT). To the west, in neighboring Waller County, more than 20,000 acres of original prairie has been protected by the Katy Prairie Conservancy. 

In addition to supporting native wildlife, native prairies can sequester between a half-ton and 2 tons of carbon per acre in its root systems, which can reach up to 15 feet underground.

They also can retain significantly more water during heavy rain events than residential and commercial land.

“We call them the hardest working ecosystems in the world,” says Laura Huffman, regional director of The Nature Conservancy in Texas.

When the NPAT bought the Deer Park Prairie in 2013, it was bordered by some homes, a cemetery, and fields. Today the fields have been replaced by subdivisions. Private land around the Katy Prairie that used to cost a few hundred dollars an acre can now cost tens of thousands. And while those prairies are protected, in a business-friendly state like Texas there is always a tension between environmental protection and economic development.

It’s “a touchy subject,” Ms. Barbato admits.

“It’s really difficult to see the sprawl,” she adds. But “if we can preserve or restore prairie at the same time then that would be a win-win for everyone.”

“A new attitude”

There is a general consensus among ecologists and urban planners that prairies can be beneficial, though research has yet to quantify the benefits for Houston. There is likely a limit to their floodwater storage potential. During Harvey, for instance, Harris County’s prairie wetlands only absorbed about 5% of the rain that fell, according to one estimate.

But the importance of pocket prairies, advocates say, should also include their educational and symbolic value.

When Houston conservation groups began working together on prairie restoration in 2009, “one of the first things that people said is, ‘No one knows prairies around here,’” recalls Jaime González, who manages urban conservation programs in Houston for The Nature Conservancy.

“We knew that if we’re going to uplift this story [of prairies and their benefits] we needed to put prairies throughout the city,” he adds.

Schools and highly trafficked areas like Hermann Park – one of the most visited city parks in the country – were targeted as sites for pocket prairies. Local landscape architect Beth Clark worked with the Katy Prairie Conservancy to create a “nine natives” project identifying nine attractive native plants that the average Houstonian could find and plant in their garden – a way for locals to build prairie-like greenspaces that are easier to maintain and not as wild-looking as genuine prairie.

Tapping Texas pride

Conservation groups have also seized on the connection prairies have to Texas identity, focusing on what Ms. Barbato calls “heart-grabber species,” such as bluebonnets (the state flower of Texas) and milkweed (the exclusive nursery of the monarch butterfly).

“If you take these icons of Texas, and you can reconnect it with the landscape, that’s when people will become fervent defenders,” says Mr. González.

In a sense, advocates say, prairies offer Houston residents a connection to their past. Longhorn cattle historically grazed on the prairie. And the prairie’s tall grass even helped secure Texas independence, covering a sneak attack on Mexican General Santa Anna in the pivotal Battle of San Jacinto.

At the same time, advocates see the prairie as key to building resilience into Houston’s future.

A year after Hurricane Harvey, then-Harris County Judge Ed Emmett called on officials to “permanently preserve and protect what remains of the Katy Prairie.”

“Let it be a sponge,” he reiterated this past weekend during a panel discussion on Harvey recovery at the Texas Tribune Festival. 

‘’We can make ourselves as resilient as possible,” he said, “but we have to work with nature where we can.”