Variable milfoil (Myriophyllum heterophyllum) is an invasive plant that became established in Lake Winnisquam sometime around 1995. Milfoil growth has been primarily confined to the northern end of the lake near the loon sanctuary, Winnisquam Marine, Jay’s Marina, Sunray Shores (a dredged channel to developed land in Belmont), Ephraim’s Cove and Mallards Landing. NHDES surveys the lake each year to document where the areas of infestation are, and to determine if there are any new areas of growth. See the 2020 Milfoil Management Map for herbicide treatment, the Map for Diver Assisted Suction Harvesting (DASH), and the most recent Long Term Variable Milfoil Management Plan 2020 documented by NHDES.
Prior to the creation of the Winnisquam Watershed Network in 2017, milfoil management in Lake Winnisquam was conducted on a localized basis and some areas of infestation had not been treated in more than 10 years. The WWN’s approach is to conduct milfoil management throughout the lake each year with the ultimate goal of reducing or eliminating the milfoil growth in infested areas and preventing further spread. Funding for the program comes from State grants, local matches from each of the five municipalities on the lake, and contributions from neighborhood associations and members. For more details on variable milfoil, see the Environmental Fact Sheet from the NHDES.
The 2020 Milfoil Program is underway and so far we’re seeing a definite reduction in growth in the areas previously treated. Aqualogic spent several days in May conducting diver-assisted removal of milfoil in the channel at the north end, Mallard’s Landing and several other locations around the lake. They will return later this summer to do any additional work that is needed. Our weed-watchers will be on the lookout for signs of milfoil in any new areas and will report back to our weed watcher coordinator. In June SOLitude Lake Management will be applying ProcellaCOR to milfoil in Sunray Shores, Jay’s Marina and an area of the southern basin near the outlet in Tilton, where the milfoil growth is heavier and the roots are embedded in rocks making it harder for divers to get at. This is the same “reduced risk” herbicide that we used last year at the north end of the lake and in Jay’s Marina with good results. We’re happy to report that the reduction in milfoil at the northern end of the lake requires only diver assisted removal.
For the second consecutive year the WWN implemented a Lake-wide Management Plan for invasive variable milfoil. The plan called for a controlled herbicide application in approximately 30 acres of the lake (primarily in the northern channel, Jay’s Marina and Ephraim’s Cove), and up to 20 days of professional diver-assisted harvesting in areas of the lake with less-dense milfoil growth. View the 2019 Milfoil Management Areas Map. Bids for the 2019 program totaled about $46,000. The WWN has was awarded an $11,600 Exotic Plant Control Grant from NHDES that funded 25% of the work, and received contributions from each of the five municipalities on the lake. In order to fully fund the program we solicited contributions from neighborhood associations and received donations from WWN members as well as local businesses and citizens interested in helping protect Lake Winnisquam.
The 2018 Comprehensive Variable Milfoil Management Program for Lake Winnisquam included the removal of variable milfoil from a number of locations along the lakeshore (including new locations identified by our new Weed Watcher Program volunteers) by diver-assisted harvesting by Gilford-based Aqualogic Inc. Throughout the summer a total of 843 gallons were removed. This was followed in September by a controlled herbicide application by SOLitude Lake Management in 19.5 acres where the milfoil growth was the densest. We were not able to treat the milfoil in Jay’s marina this year due to the recent reactivation of a public water supply well in close proximity to the treatment area there. We’re looking to treat this area next spring with an alternative herbicide that has recently become available and does not have the same use restrictions.
Our milfoil management program was funded through a grant from the New Hampshire Department of Environmental Services (NHDES), local matches from the towns of Meredith, Belmont, Tilton and Sanbornton and the City of Laconia, and contributions from several neighborhood associations, as well as our members. We extend our deep appreciation to all. This is the first time that management of variable milfoil has been undertaken on a comprehensive, lake-wide basis on Winnisquam, and it’s our intent to continue this collaborative effort for as long as is necessary to control the growth of the milfoil and prevent further spread. We’re currently working with the NHDES to finalize next year’s comprehensive milfoil management plan and have begun soliciting bids for the work.