In addition to continued efforts to eradicate Giant Salvinia from the Barnett Reservoir, Pearl River Water Supply District (PRVWSD) officials are also considering long-term strategies for preventing the spread of non-native, invasive plant.
According to Barnett Reservoir General Manager John Sigman, the PRVWSD has already spent more than $250,000 over the past year attempting to rid the reservoir of Giant Salvinia since it was first discovered in October 2018.
The next steps for treating the Giant Salvinia are lowering the lake level to 295 feet beginning December 13 and beginning another round of burning and spraying.
The Giant Salvinia task force – a combined effort of the PRWSD, Mississippi Department of Wildlife, Fisheries and Parks and Mississippi State University – recommended that the lake level be dropped four feet, to 293.3, to dry out all areas of Salvinia growth for up to three months.
However, Sigman said they agreed to drop the water level to 295 at the urging of reservoir leaseholders, both residential and commercial.
“Our experts doing the treating and doing the work would have preferred 293 to get at some of the pockets of Giant Salvinia, but they have agreed that they can work with 295,” Sigman said.
Last year, the lake level was lowered with the hope that the winter weather would freeze the plant and kill it off. Sigman said they are not counting on that this year.
“A freeze would be beneficial, but we can’t count on that,” Sigman said. “So, we are going to lower the lake and go with the herbicides.”
Looking at long-term options, Sigman said they will likely keep the currently infected areas boomed off. A baffle system is also being considered for underneath the bridge, so that Pelahatchie Bay can eventually be reopened to the rest of the lake.
Sigman said a boom system for deterring wind-blown Salvinia is also an option.
Many of these efforts come with a hefty price tag. Sigman said they have purchased $100,000 worth of booms over the past year, which they have used to block off infested areas and close off the Pelahatchie Bay from the rest of the lake. The booms cost approximately $10 per foot.
In addition to the booms and herbicides, three boat cleaning stations were purchased to help prevent the further spread of the plant by boat.
Two of the cleaning stations, which cost approximately $38,000 each, were purchased with a grant.
While treatment has been quite costly, Sigman said the biggest challenges PRVWSD has faced have been the inconvenience for lake users and leaseholders and raising awareness among boat owners about the process of cleaning, draining and drying.
“The cleaning stations will help if people will use them,” Sigman said. “You have to look at your boat and trailer. That’s a challenge.”
“It only takes a few minutes before and after each boating trip to inspect a boat for hitchhiking plants,” Sigman has said. “Remember: clean, drain, dry. Clean your boats, trailers and accessories. Drain your holding tanks. Dry all your equipment.”
According to a report from Mississippi Department of Wildlife, Fisheries and Parks, Giant Salvinia has been found in several other Mississippi waterways, including Pickwick, Bay Springs, Columbus and Aberdeen Lakes, Okhissa and the Pascagoula River marsh.
Sigman said many of these are following similar treatment plans as the reservoir. However, none have gotten as close to eradication as the Barnett Reservoir.
“We have been successful in eliminating what our experts say is about 98 percent of the Salvinia and controlling 98 percent of its range,” Sigman said.
He attributes that success to the task force’s plan and recommendations.
“As most of the Southeastern United States is learning, this is a horrible threat to our waterways and one that we will be fighting from now on,” Sigman said. “It is imperative that all our partners, including our boaters and fishermen, residents and visitors, become part of the solution. Preventing the spread of Giant Salvinia should be on the minds of everyone.”