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‘Aggressive noxious aquatic weed’ infests Gapway ponds

Giant Salvinia chokes Richardson Pond in this image from state DEQ manager Rob Emens


     Giant Salvinia, described as “a very aggressive noxious aquatic weed,” has been found in two ponds in the Gapway area of Columbus County, west of Tabor City, county leaders are learning.

     Rob Emens, Aquatic Weed Program Manager with the state’s Division of Water Resources, Department of Environmental Quality (DEQ) offered details on his findings in an e-mail Friday to County Manager Mike Stephens and Cooperative Extension Director Dalton Dockery.

     Emens said an infestation at Richardson Pond in the Gapway area off of Sidney Cherry Grove Road.

     “After my initial site inspection I discovered that Buffkin Pond is also heavily infested,” Emens said.

     Richardson and Buffkin ponds are relatively near each other, separated by Gapway Church Road.

     “Cursory survey work of the area” indicates the infestation may be limited to the two ponds “and areas downstream,” Emens wrote. He described the plant as “regulated, therefor, illegal to propagate, sell/trade, transport, etc.  NCDA&CS is the state agency that holds regulatory authority.”

     Giant Salvinia floats, and “due to the heavy infestation in Richardson Pond a significant number of plants have been pushed through the water-level control structure and have been carried downstream,” Emens wrote.

Previously eradicated?

     North Carolina has limited experience with Giant Salvinia, a plant Dockery said is indigenous to South America. Discovered in North Carolina some two decades, it was “removed from several sites and since 2008 we considered NC to have no known infestations,” Emens wrote.

     It was listed by the US Department of Agriculture as a “noxious weed” in 1983, Dockery said, and found in a small pond in South Carolina in 1995.

     “Infestations currently exist in Texas, Louisiana, Mississippi, Alabama, Georgia, Florida, Arizona, California, and since 2000, North Carolina has been added to this list,” Dockery said.

Real threat

     Leaves of the plant are small, Dockery said, similar in size and shape to fingernails.

     “Leaves of young plants tend to lie flat upon the water,” Dockery said. “The largest leaves may grow to about two inches. Giant Salvinia can grow very rapidly. Under favorable conditions, infestations will double biomass in 4 to 10 days. Imagine if the tree in your yard doubled its size every week.”

     When mature, the plants “create a dense floating mat,” Dockery said. “In places where Salvinia has not been controlled, mats have grown to be two feet deep.”

     That, Dockery said, chokes other vegetation, displaces fish, and can impact reptiles, amphibians even wading birds and other waterfowl.

     Impacts to recreation and drinking water supplies are also common, Dockery said.

     While it’s not clear how the Giant Salvinia made its way into local ponds, “boats and other personal watercraft” also carry the weed from one body of water to another. Just a small amount can multiply rapidly, Dockery said.

     Dockery said planning has begun to deal with the issue.

      For more on this story see today’s Tabor-Loris Tribune in print and online.