GOING DEEP Resaca restoration begins at Gladys Porter Zoo


The cry of an exotic bird cut through the roar of two large diesel-powered pumps as a yellow-helmeted diver emerged from the green soup of the zoo resaca.

In his hands was a large, muck-covered plastic roof panel, deposited in the resaca by Hurricane Dolly. Much more junk likely will be pulled out of the water as the dredging project proceeds.

It’s part of the first phase of the Brownsville Public Utilities Board’s resaca restoration project,” which started in March 2013 at the OldCityCemetery and covers four resacas in all.

The dredging operation moved to the zoo for a short time after the cemetery dredging was complete before moving to the Dean Porter Park resaca, where dredging is nearly done.

Now BPUB is back at the zoo, where dredging required a different approach due to the narrowness of the resaca, bridges and other impediments. Divers with Fort Worth-based American Underwater Services started work last week at the north end of the resaca near the aviary.

Working in shifts, the divers use a 6-inch-diameter pipe connected to the powerful pumps to suck up silt and other debris that’s found its way into the resaca over the decades since the zoo was built.

Zoo Director Pat Burchfield said the resaca restoration is a “very big deal from the zoo’s perspective.”

“Our resaca, like the city resacas, was doing exactly what nature intended resacas to do, is silt in over time and become land again,” he said. “We had reached a point where we actually had two island exhibits we couldn’t put animals on anymore because the water was too shallow.

“At times it got pretty desperate around here because we actually had animals walking off the island exhibits.”

Another problem is that dead algae creates an unpleasant smell on hot summer days, Burchfield said.

“Even though the zoo was spit-shine clean people would come in and say, ‘Oh, the zoo’s dirty,’ because of the odor from the resaca,” he said.

Burchfield said the zoo project will include planting more native plants to encourage the return of marine animals that used to live there.

“I’m sure some of our zoo visitors will recall coming here and seeing 40- and 50-pound catfish that they fed and big gar and sailfin mollies and Rio Grande cichlids,” he said. “This place was a plethora of native resaca inhabitants.

“The sediment level and the shallowness of the water affected the temperature, particularly on hot days. There’s only a few things — gar in particular — that can survive in that kind of water. We’ve still got probably a couple of 5- or 6-footers out there.”

Burchfield said the dredging should take care of the resaca for the next 40 years. Ideally, they’ll be able to establish a maintenance program to prevent things from getting so bad in the future, he said.

Rene Mariscal, water resource manager for BPUB, said all of Brownsville’s resacas are full of silt and trash — some worse than others. Dredging crews hauled more than 200 tires out of the cemetery resaca alone, he said, while the park resaca was comparatively clean.

No dredging program of this magnitude has ever been undertaken in the city, Mariscal noted. When the zoo is complete in three or four months, dredging will resume at Dean Porter Park before moving on to Resaca Boulevard, he said.

In addition, bank improvements for the cemetery resaca, such as re-sloping and planting native vegetation, will likely break ground in January or February, Mariscal said. Eventually, BPUB plans to dredge the city’s entire resaca system, he said.

The utility company undertook the project in order to create more storm water capacity to ease flooding during heavy rains; to provide more raw water storage capacity for drinking water; and to improve wildlife habitat, beautify the city and improve quality of life, Mariscal said.

Also planned are a couple of storm water management ponds, which will capture sediment and trash when it rains to prevent it from flowing into resacas, he said.

Planting vegetation along banks also slows down the silting process, Mariscal said. Finally, storm water “interceptors” are planned for some locations, he said.

“It’s essentially a big storm drain, but that’ll help catch the mud,” Mariscal said. “It’s like a separator.”

He said BPUB studied resaca fish populations before dredging to see what the impact would be and that, indeed, it seems to be increasing the number of fish.

“We’re noticing a little bit more fish in Dean Porter Park,” Mariscal said. “Now you’ve got a lot more (water) volume.”

He said the park project dredged as much as 9 feet in some pockets before hitting clay, though on average the new depth is 6 to 6½ feet — a vast improvement considering how badly the resaca was silted up in some places.

Mariscal said BPUB estimates that 14,000 cubic yards of material would be sucked out of the zoo resaca before it’s all over and that the average new depth will be around 4 feet.

Initial equipment costs for the dredging project were about $8 million, with around $1.8 million budgeted annually as the project continues, he said.

BPUB spokesman Ryan Greenfeld said $1.7 million has been budgeted for the current fiscal year. The board has received $300,000 in grants from the EPA’s Gulf of Mexico Program and $100,000 from the Brownsville Community Improvement Corporation, he said.

Both grants are tied to the cemetery resaca project, Greenfeld said, noting that BPUB is pursuing additional grants to help fund the restoration project. No rate increases were needed to fund the project, he said.

Lee Malone, project manager for American Underwater Services and a commercial diver for 20 years, said palm fronds and skins have presented the biggest challenge, though the chunky material lining the banks in some spots can be troublesome as well.

“There’s bricks and larger size rocks the size of a bowling ball that won’t go through,” he said. “We have to work around some stuff. … “When they’ve got (BPUB’s) big booster pump going behind our pump it pulls pretty hard. Whenever it gets a hold of something it wants to go.”

Plus, divers can’t really see what they’re doing down there, Malone said.

“For the most part as we get started there’s zero visibility,” he said. “But as we get depth and as we get the sediment removed, we start to see more clarity.”

As commercial diving gigs go — and American Underwater Services has done it all —Malone said the zoo project isn’t bad, plus it’s the company’s first zoo. Malone said.

“We’ve had our hiccups just like every startup, but it’s actually a very nice job,” he said. “It’s going to do a world of good for this resaca and the zoo, so it’s worth the effort.”



Please enter your comment!
Please enter your name here

This site uses Akismet to reduce spam. Learn how your comment data is processed.