Remodeling Nature’s Landscape

What’s Happening to the Banks in Buffalo Bayou Park

Will It Last? Removing Invasives is a Good Thing

April 20, 2023

It looked terrible. Dead stalks sticking out of the ground, banks denuded and sprayed with blue-green herbicide.

People have been wondering what’s been happening in Houston’s beloved Buffalo Bayou Park between Sabine and Shepherd streets.

It’s the work of the Harris County Flood Control District and the Buffalo Bayou Partnership, the public nonprofit which manages the 160-acre city-owned park along with Flood Control. The good news is that a large part of what they have been doing is removing invasive species, like Johnson grass and other noxious, domineering stuff that floats down the river from yards and fields. They’ve been “stabilizing” the bank with biodegradable coir logs and in the last few weeks spraying native seed mix on the bare banks.

South bank of Buffalo Bayou downstream of the Dunlavy in Buffalo Bayou Park, April 10, 2023.

It’s all part of a $960,000 Harris County plan, in the works since 2019, called the “Buffalo Bayou Park Revegetation and Biostabilization Project.” The goal is to revegetate the banks of Buffalo Bayou from Shepherd Drive to Sabine Street and provide enhanced natural infrastructure to Buffalo Bayou Park, particularly in those areas scraped and bulldozed by Flood Control in 2019-20.

For that $10 million federally-funded “repair” project, Flood Control removed native vegetation and lined sections of the banks with concrete rubble, known as riprap, even though the design engineer, Jones Carter (now known as Quiddity), apparently rejected riprap, (p. 4). Even Flood Control in the past has rejected riprap, (p. 6) as well as the US Army Corps of Engineers (p. 4), and numerous other federal agencies. For more explanation of why riprap damages the stream, the environment, can even contribute to bank failure and increase flooding, see page 7.

Of course, the river has its own ancient and purposeful landscaping plan: first colonizing and stabilizing plants, working in succession, turning sand into soil, preparing the way for drifting willows and other native trees. But humans have other landscaping ideas. We’ll see how long those human plans last.

The Planting Project

We visited the project with Gabriela Sosa, since 2021 the conservation manager for the Buffalo Bayou Partnership. Dr. Sosa grew up in Brownsville, on the Texas coast, where she was inspired to pursue a career in ecology by the Sabal Palm Sanctuary. “I didn’t know ecology could be a career,” she said.

Her vision for the park is a “wildlife corridor” for birds and other creatures, including humans. A “greenspace in the middle of downtown.”

“Most people don’t get to see nature,” she said, as we toured the project in a golfcart, getting out to inspect elderberry bushes, Maximilian sunflowers, lantana, sorrel, late boneset, and more.

Dr. Gabriela Sosa loving elderberry in Buffalo Bayou Park. March 16, 2023

She was enthusiastic about keeping the elderberry, as we inspected the bush along the Greentree Nature Area on the north bank. “Previously we would have mowed the elderberry. But it’s great habitat for birds. We’re keeping it.”

In addition to killing off or removing invasive species like Johnson grass, elephant ear, castor bean, and Chinaberry trees, the project has removed swathes of native plants like ragweed, goldenrod, other types of sunflowers and more. Her objection was that those plants take over and dominate, shading out other plants. The goal is more diversity. And more deep-rooted plants, she said, pointing to the roots of an uprooted sunflower. Workers have been carefully picking out ragweed and sunflowers on the lush banks of the bayou. In other areas, however, the banks have been sprayed with an “aquatic-label” herbicide, meaning it’s been approved for use near streams. Technically, according to Flood Control, it’s Roundup Custom for Aquatic and Terrestrial Use, which is glyphosate, a controversial herbicide banned in some countries, cities and states.

Lots of Trees

The project has some fifteen replanting/monitoring areas on the north and south sides of the popular park. Sosa says the plan is to monitor the planting by taking photos every month. Flood Control’s contractor is planting hundreds of more than thirty different species of native trees, as well as shrubs and grasses, seeding the banks with a mix from Native American Seed company that includes cereal rye and Riparian Recovery Mix.

The cost of the project includes two years of maintenance and weeding out undesirable species, according to Flood Control.

The work is being done by Resource Environmental Solutions (RES), which in 2021 bought out Lecon, the firm that did the original scraping and bulldozing of the bayou in the park for Flood Control in 2013-2015.

Fields of Dreams and Sandy Banks

Field of wild pepperweed and other wonderful stuff on north bank of Buffalo Bayou in Buffalo Bayou Park, March 14, 2023

On a stroll through the park some weeks ago, we saw bright, lovely meadows of pepper weed and tasty wild garlic, dewberry vines, willows, hawthorn, Mexican plum, Eastern redbud (also tasty), magnolia, verbena and wild geranium, and much more.

We also saw drainpipes sticking straight out of the recently seeded bank, potentially dropping stormwater directly onto the nearly bare soil. As we have previously reported, stormwater outfalls at right angles to the bank cause turbulence and erosion, effectively damming the flow, and are a violation of federal and local regulations. Perhaps this issue was outside the scope of the fluvial geomorphic assessment of the bayou conducted for Flood Control by a Houston-based firm, HydroGeo Designs, in 2019-2020. Dated July 2021, the assessment, which focused on the river from Shepherd through downtown to Jensen, was intended to better understand the shape and movement of the bayou and nature’s very specialized riparian zones adjacent to it, “with the objective to improve the overall stability and resilience.” (p. 34)

Stormwater pipe draining onto newly planted banks on south bank in Buffalo Bayou Park. Photo April 16, 2023.

Something else not generally understood: Buffalo Bayou, like many rivers, has always had sandy banks, as opposed to idyllic park-like grassy green banks. (See this 1912 photo of the banks near Memorial Park by landscape architect Arthur Comey.) See also this 1900 photo of boys swimming off the high sandy bank near what is now the Hogg Bird Sanctuary and the Bayou Bend Collection and Gardens. (Caution: no bathing suits, expensive then.)  

It is common for consultants, including engineers and landscape architects, to claim that the bayou’s sandy banks are the result of prolonged high-flow releases from the 1940s federal dams upstream drowning the vegetation. The 2021 geomorphic assessment concluded something similar. (p. 10) Interesting to note that HydroGeo Designs, the firm that conducted the assessment, is a specialist in “natural channel design” and the controversial Rosgen Method. The original $5 million scraping and rearranging of the park’s channel and banks by Flood Control in 2013-2015 was billed as a “natural stable channel design” project. It has failed repeatedly ever since. (See also here and here.)

But no doubt things are looking up.

Left image: Buffalo Bayou north bank below Shepherd Bridge on Sept. 9, 2020, before 2020 “repairs” by Harris County Flood Control District. Right image: the same bank on April 16, 2023, during recent restoration work by Flood Control.