The Eelgrass Battle
TVA and Partners Work to Wrangle Invasive Species at Guntersville
Roy Bryant reminisced about his crew club days, when he and his teammates could spend an afternoon rowing across Guntersville Reservoir.
It had always been one of his favorite hobbies.
On more than one occasion, however, they’d encounter a tangle of vegetation that made it difficult to enjoy an afternoon of boating.
The culprit? Eelgrass.
Natural Resources specialists know this particular variety by another name.
“The common name is rockstar,” David Brewster, TVA Natural Resource Management – West Operations manager, said. “That’s because it grows so fast and does so well.”
This invasive plant’s resilience has been the bane of many who visit Guntersville Reservoir in Alabama.
It is believed to have first appeared in the reservoir about 15 to 20 years ago, likely originating from Florida. Biologists officially confirmed its presence about five years ago.
In that timeframe, it has spread downstream to Wheeler, Wilson and Pickwick reservoirs, as well as upstream to Nickajack Reservoir. Small populations have been found at Chickamauga Reservoir.
Rockstar eelgrass is a hybrid of two non-native species of aquatic plants, Vallisneria denseserrulata and Vallisneria spiralis.
At Guntersville Reservoir, aquatic plant biologists have recently been unable to find or collect a native species of aquatic plant, Vallisneria americana.
That’s because rockstar eelgrass has displaced it.
While TVA specialists primarily use herbicide treatment to manage eelgrass that grows on the reservoir bottom along developed shoreline, the growing plant itself is less problematic than portions that break free from the reservoir bottom, either naturally or from waves and wind.
Floating eelgrass has become a leading problem at Guntersville Reservoir.
“The floating mats can be acres in size and freely move with the river current and wind on the reservoir,” Brewster said.
Scraping the Surface
There aren’t many efficient options for removing floating eelgrass.
Typically, TVA teams and their contracted partners will physically remove the floating plant from Guntersville Reservoir.
And it’s a never-ending battle.
“Once a mat is removed from an area, another will take its place within hours if there is no significant change in current or wind direction,” Brewster said.
About 95% of the eelgrass removed from Guntersville Reservoir is taken from the water’s surface.
This year alone, work crews have removed a staggering 120,000 cubic yards of floating eelgrass from Guntersville Reservoir.
TVA’s strategy involves removing as much of the floating plant as possible from the reservoir’s open-water areas and the river channel.
In boat lanes and access lanes, TVA teams use a harvester to clear the waterways. While this doesn’t eliminate the problem, it does help reduce the amount of floating plant near shoreline areas.
TVA teams and contractors do not remove floating eelgrass from shoreline areas.
Along private shoreline areas, property owners are free to remove the plant as needed.
It’s imperative, however, they place it on land once it’s removed – preferably at a location above TVA property, noted Stephen Turner, program manager for TVA Aquatic Plant Management.
To properly manage native aquatic wildlife and maintain recreational access and activities, it’s critical to manage invasive plant species.
Rockstar eelgrass and other non-native species invade many areas used for recreational activities, such as water near boat ramps, piers, shorelines and other public access points.
“It’s important to remove invasive species in certain areas to enhance recreational opportunities,” Brewster said. “Removing these plants provides easy access in and out of the water.”
TVA specialists and contractors can use EPA-approved aquatic herbicides to effectively control rooted, growing plants on developed shoreline.
In public access areas such as boat ramps and parks, TVA funds these herbicide treatments.
Along private and commercially developed shorelines at Guntersville Reservoir, TVA partners with My Lake Guntersville, which this year is covering half the cost of these herbicide treatments.
Bryant, a WET Foundation chairperson, is grateful for the work undertaken to combat invasive plant species.
His foundation maintains a schedule of treatment programs at Guntersville Reservoir.
“We appreciate the efforts to keep the lake clean,” Bryant said. “It’s a very difficult job.”