The Nature Conservancy is rebuilding eroded streambanks in Missouri to reduce sediment pollution, which is one of the largest sources of water contamination in the state.
Since the summer of 2017, conservationists have been working with environmental engineers to stabilize streambanks at LaBarque Creek near Pacific. They're also doing so along the Elk River in southwest Missouri, where sediments have polluted the watershed. Through bioengineering techniques, they repair the streams by using deep-rooted native plants, biodegradable coconut fibers and other natural materials, such as wood, to keep the banks from depositing sediments into the water.
The work, when successful, can improve water quality, provide better wildlife habitat and prevent erosion caused by flooding.
After months of monitoring the project sites, the Nature Conservancy has seen the benefits it hoped to achieve. At LaBarque Creek, for example, conservationists have seen fish species, such as the long-eared sunfish, reappear after the restoration work. Sediment pollution can be harmful to aquatic life, said Barbara Charry, the conservancy’s Lower Meramec River coordinator.
“The sediment itself gets into the water and so animals that filter that water get suffocated,” Charry said. “Fish that are spawning and leaving their eggs on the bottom, those are going to be smothered and they’re not going to be so productive.”
Before the bioengineering work, the land surrounding LaBarque Creek was a bare, former ballfield. The stretch where the Nature Conservancy worked is on a property belonging to Washington University’s Tyson Research Center. The center’s staff had informed conservationists about the erosion problems at the creek, said Steven Herrington, the Nature Conservancy’s director of freshwater conservation.
“There was no vegetation out on the site,” Herrington said, ”and as the water would come from upstream that way, come down through this bend, it just kept taking chunks of the stream with it.”
The two sites also have proved resilient to major floods, which is important, given how climate change could bring more heavy rains to Missouri, Charry said.
“This kind of solution reduces that flood risk,” Charry said. “It slows that water down, it allows it to
dissipate more naturally.”
The LaBarque Creek site has not shown signs of erosion, despite three flood events in the past year, according to conservationists.
A more traditional approach to stabilizing streambanks would involve concrete and rip-rap, or quarry rocks, to prevent erosion. Bioengineering is less costly, creates habitat for wildlife and looks more appealing, Charry said.
“This is highly engineered but looks completely natural,” Charry said, as she stood at the LaBarque Creek site.
Because of the wide-ranging benefits to the environment, the Nature Conservancy wants the Environmental Protection Agency to consider making bioengineering as a part of its plan to clean up the Big River Mine Tailings Superfund site.
The Elk River project covered 1,650 feet and cost $652,000. The LaBarque Creek site covered about 300 feet and cost $40,000.
The bioengineering method has been used in past decades to restore salmon and trout populations in other parts of the country, but this is the first time it’s been used in Missouri. The Nature Conservancy plans to use such techniques to restore a portion of Keifer Creek at Castlewood State Park next year.
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