Man-made wetlands are new water source for Tarrant
06/28/2014 5:53 PM
06/28/2014 5:54 PM
The water moving through the Trinity River is murky to say the least.
Churning from recent rains, it is a muddy brown.
But that dirty-looking river water about 110 miles southeast of Fort Worth is giving Dallas-Fort Worth a valuable new supply while also providing a key habitat for wildlife.
After beginning with a small 2-acre test facility in the early 1990s, the man-made wetlands have grown to 2,000 acres. The largest phase — 1,600 acres — was completed in October, making this the first year that the wetlands’ full impact has been felt.
Last week, the wetlands were providing about 55 million gallons a day — or about 17 percent of the supply for the Tarrant Regional Water District.
Officially called the George W. Shannon Wetland Water Reuse Project, it pulls water from the Trinity and has it slowly migrate through the wetlands in about a week’s time. Wetland is a generic term for land near streams, rivers, lakes and coastlines where water is naturally trapped. A wetland’s vegetation, soils and micro-organisms filter out pollutants as water passes through.
In these man-made wetlands, the water is first pumped into one of the sediment basins, where much of the sediment drops to the bottom, then goes into wetland cells, which look like ponds or pools that contain vegetation.
“These plants are taking those constituents out of that water and using them for their growth,” said Darrel Andrews, assistant director of the water district’s environmental division. “The soil binds some of those nutrients as well. These act as the filter. That’s what’s removing those nutrients before it gets to the end of the wetland system and it’s pumped into Richland-Chambers Reservoir.”
Texas has seen an increased emphasis on conserving and reusing water. Under the state water plan, reuse projects like the wetlands are expected to grow ninefold over the next 50 years.
Tarrant Regional, which has 1.8 million customers, plans to build similar-size wetlands at the Cedar Creek Reservoir, but that project is at least a decade away.
The North Texas Municipal Water District, which serves suburbs east and north of Dallas, also has The East Fork Wetland Project in Kaufman County.
Enough water to serve Arlington
Ken Kramer, water resources chairman for the Lone Star Chapter of the Sierra Club, said reuse projects will become increasingly common as water providers search for alternatives to reservoirs. Tarrant Regional’s wetlands project cost $75 million, a fraction of the estimated $3.4 billion it would take to build the controversial Marvin Nichols Reservoir in Northeast Texas.
“I think those kind of reuse projects are going to be part of our near-term and long-term water supply strategies,” Kramer said. “As environmentalists, we certainly have to be careful about reuse projects not having unintended consequences on necessary in-stream river flows for certain habitats and certain species, but I think those things can be managed.”
While it took two decades to complete, Andrews said, this type of wetlands project can be duplicated in any place with access to water from a wastewater treatment plant and a nearby reservoir to store the filtered water.
In the long term, the wetlands project can not only delay the need for new reservoirs but also ease the strain on the West Fork reservoirs of Eagle Mountain Lake and Lake Bridgeport, which have been hit hard by the drought. The wetlands produce about half the annual yield of the two reservoirs, nearly enough water for Arlington, with a population of 379,577, according to the latest census estimates.
“The wetlands produces 63,000 acre-feet per year, which equals about 56 million gallons a day, so it supports about 343,000 people,” said David Marshall, engineering services director for the Tarrant Regional Water District.
The wetlands are permitted to have a capacity of about 90 million gallons per day.
Good for wildlife
But the project is about more than just water — it’s about serving as a haven for wildlife.
Part of Texas Parks and Wildlife’s Richland Creek Wildlife Management Area, the wetlands have attracted more and more birds through the years.
Matthew Symmank, a wildlife biologist who oversees the wildlife management area, estimated that thousands of birds were at the wetlands last week, including several types of egrets, great blue herons, wood storks, white ibises and American white pelicans.
During a drive through the wetlands, hundreds of birds could be seen roosting in the trees while others waded slowly through the water. Gators, deer and feral hogs also roam the area.
The bird show isn’t limited to the warmer months.
In winter, the number soars even higher because thousands of migratory birds descend on the area. Symmank said the bird counts have steadily increased as the wetlands have grown.
“From our perspective, these wetlands are very beneficial to all sorts of native wildlife,” Symmank said. “The main thing we try to focus on here is habitat for migratory birds.”
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