LEICESTER/SALISBURY — When the last ice melts off, the annual battle for Lake Dunmore will begin again. On one side: an army of volunteers, paid divers and milfoil specialists. On the other: an underwater invasive plant called Eurasian watermilfoil.
The population of milfoil in Lake Dunmore and Fern Lake has grown tenfold since 2009, and is expected to double again this season, according to Jay Michaels, a trustee of the Lake Dunmore and Fern Lake Association (LDFLA)
The association takes the lead in trying to eradicate — or at least check the growth of — the milfoil, but it is having trouble keeping up with the invasive species. Despite members’ best efforts and expensive arsenal, which includes a specialized milfoil suction boat called Millie, the lakes are in danger of being choked by the plant.
The towns of Leicester and Salisbury have more at stake than an ecological ideal. Cleaner lakes mean higher property values and greater consumer traffic in the area.
“The public recreation area and the town’s grandlist property values are at risk,” said Michaels.
Despite pulling the invasive by hand and using Millie to harvest 1,174 bushels of milfoil last year, the invasive still outpaced its opponents.
“Up until 2008, we could say the milfoil was under control by the end of the season,” Michaels said. “These past few years, there has been a larger and larger base for the milfoil to build on at the end of the season. That’s why you see the exponential growth.”
In 2005, divers pulled only 9.4 bushels from both lakes. Michaels projects that 2012 will see the harvest of 2,500 bushels.
But, better harvesting methods mean higher harvests, so the alarming statistics are partially due to Millie and a similar boat that the association plans to purchase this year. Each pontoon boat and its retrofitting costs $18,000.
This year the LDFLA will focus most of its finances on the suction technique, though Michaels outlined several other control methods.
“We’re staying abreast of the options. There’s chemical treatments, bottom barriers, and biological treatments,” Michaels said. “None of those are in the plan for this season, but the options are there.”
Professor Sallie Sheldon, a researcher of biological milfoil controls, believes that a large ecosystem like Lake Dunmore and Fern Lake will require a cocktail of treatments, of which biological management is only one.
“Typically you’ll use all different types to control milfoil in a single lake,” Sheldon said. “It’s what they call integrated pest management.”
Fifteen years ago, Professor Sheldon published research on a small beetle that ate Eurasian milfoil and nothing else. The insect, Euhrychiopsis lecontei, also called the Eurasian milfoil weevil, may be part of the answer.
Unlike chemical treatments, the weevils slowly balance the invasive population with native milfoils. As a specialist treatment, it leaves the rest of the underwater ecosystem intact while targeting the invasive.
“We can’t say we’ll take it out in one year, like a chemical herbicide,” Sheldon said. “What we can say is that we’ll see significant decline within three years.”
The weevil is a native species, and it’s been used successfully in 18 states and six Canadian provinces to control milfoil. Sheldon has personally seen it at work in several Vermont locations, including Lake Morey, Lake Eligo, Fairfield Pond and Mallett’s Bay.
“Mallett’s Bay is an example of a really great milfoil population,” she said. “There’s native species interbedded with a small amount of Eurasian Water milfoil. The insects are present there, too.”
While the milfoil weevil isn’t as satisfying as ripping the plant up by the roots and tossing it into a floating suction machine, it seems to be effective. Sheldon was uncertain about permitting for this summer, but hopes that the weevil will soon join the ranks of milfoil fighters at Lake Dunmore and Fern Lake.
As the LDFLA gears up for this season’s campaign with a new boat and a bigger crew — they hope to start work by late April or early May — funding is a top concern. In the past, a state grant covered almost 75 percent of the association’s milfoil control costs, but it now provides less than 30 percent. The association will pick up the loss this year, but is asking residents of Leicester and Salisbury to contribute 10 percent of the support, or $16,125 apiece. The funding will be decided on Town Meeting Day.
“Mainly we just want to re-awaken people to the fact that invasive species are still a problem. We don’t think the sky is falling,” Michaels said. “But, if we don’t do more aggressive control, the sky could get pretty close to the ground.”