Tuftonboro milfoil infestations mapped by DES
Chemical treatment recommended for the Basin
|TUFTONBORO’S WINTER BASIN aerial photo showing areas of milfoil infestation (red dots) identified by the Department of Environmental Services (DES) and areas recommended by DES to be treated (green hatching). (Aerial photo courtesy of DES) (click for larger version)|
December 02, 2010TUFTONBORO — "This lake is a challenge," said Amy Smygula at the Nov. 22 Tuftonboro selectmen's meeting, in reference to milfoil control in Lake Winnipesaukee.
"A piecemeal approach won't work," the Department of Environmental Services (DES) scientist continued, as she described her findings when mapping milfoil sites in Tuftonboro.
Milfoil, a species of invasive weed that chokes out much of the competing native water plants, "comes out of Moultonborough Bay in a steady stream all summer long" covering around 400 to 450 acres" she explained.
Selectman Dan Duffy, Tuftonboro's point man on the issue, who represents the town as a member of the three-town Milfoil Committee that includes Moultonborough, Tuftonboro and Wolfeboro, described it as "the perfect weed" for its ability to thrive and spread itself along the currents. Fragments that break off the plants regenerate – one reason Duffy says it is important to "pick it up with a fish net when it floats by and dispose of it."
"The Basin is [Tuftonboro's] problem child," said Symgula. She has provided aerial maps, which can be viewed on the town's Web site or at the town offices, showing numerous red dots – markers of milfoil infestation – throughout 30.5 acres in that area.
The mapping is not yet complete, but she has mapped areas in Winter Harbor, 19 Mile Bay, where milfoil growth is most intense in the docking area, 20 Mile Bay and portions of Melvin Village shoreline.
Areas of sparse growth can easily be hand removed by divers alone or by using the Diver Assisted Suction Harvesting (DASH) methods, according to Smygula, but she recommends the use of aquatic herbicides for the areas of thicker growth, such as the Basin and the 19 Mile Bay area. She labeled some Winter Harbor areas as borderline.
Along with the maps, she provided cost estimates for the various methods. The cost of the DASH method in recommended areas will be based on the cooperative three town agreement, which involves the purchase and maintenance of equipment to be shared.
Herbicide treatments are recommended for the larger areas, to be followed in later years with hand pulling or DASH methods. Without follow up the weed can return "with a vengeance," noted Selectman Chair Carolyn Sundquist, citing the experience in 19 Mile Bay, four years after treatment. Long-term management is key to controlling the presence of milfoil, noted Smygula.
Approximately 37.6 acres to be treated in Winter Harbor, primarily for The Basin, would cost around $18,000. Approximately one acre of recommended treatment in 19 Mile Bay would cost around $5,500. It costs $100 to $150 an hour to hire divers to employ the DASH method, with individual divers working at $25 to $75 per hour.
The systemic herbicide that targets broad-leafed plants, 2,4-D, is an Environmental Protection Agency (EPA) regulated herbicide, and is the most effective treatment for milfoil, said Smygula. It is granular and falls to the bottom, to be absorbed by the roots of the plant. A license is needed to apply it under recommended guidelines, and DES uses a lower dose than recommended on the label. In the monitoring process, "We've never seen a fish or insect killed," she added.
John Trube, a Winter Harbor resident, said that he used to work for the Fish and Game Department, which in the past did not recommend using the chemical. He has been pulling the plants himself in area B (3.8 acres), as designated on the aerial map, a method that Smygula says has a better chance of effectiveness in areas C (2.5 acres) and D (.8 acre) where the soil is less organic and the bottom is more sandy, gravelly and rocky.
Resident Dan Bisson said that he thought Alton Bay used a dredging option. Smygula replied that in the seventies and early eighties, they used mowers, resulting in fragmentation that created a larger issue. Alton Bay is in their second year of monitoring and controlling the weed; Meredith is in its third, according to Smygula, who added, "The best record is Wolfeboro because of its great coordination…I always throw Ken Marschner under the bus and say call him, because they [Wolfeboro Milfoil Committee headed by Marschner] have a great plan."
She reiterated that areas B,C and D in Winter Harbor are "reasonable for harvesting", but to do that in 30 acres would be "daunting."
In answer to Sundquist's query on how soon the town needs to make a commitment, Smygula responded that permits requested in January would be in effect by May and suggested that treatment begin in June in The Basin to "get the biomass knocked back before boating begins in earnest." She noted the possibility of grants for 2012.
"We won't know until March," said Duffy, " but there are groups that want to contribute."
When questioned on toxicity of the herbicide," Smygula says that DES is cautious in having people wait a day before swimming though the label has no such restriction. She also said that DES has the research data collected by the Army Corps of Engineers on 11 aquatic herbicides and data from smaller studies, but no narrative reports to make it easy for laymen to understand. She said would look for some informative links and send them to the town to post on the town Web site.