Ossipee — November 19, 2009 — A state expert on milfoil control this week fielded questions about the safety and effectiveness of a widely used herbicide that targets this aggressive weed. Amy Smagula, the state’s exotic species program coordinator with the NH Department of Environmental Services, spoke at Monday’s select board meeting at the invitation of the Ossipee Conservation Commission. Members of neighboring lake associations from Freedom and Effingham also attended the session.
While state funding for invasive species control has dried up this year, the town could choose to replenish its milfoil control fund via a warrant article. But the board did not take action at the Monday meeting. Groups such as the Ossipee Lake Alliance has used non-chemical methods to remove milfoil from the late, but state officials believe the extent of the new and rapid spread of weeds requires more aggressive action.
Infested areas of the Ossipee Lake system include 8.7 acres of Pickerel Cove, 4.1 acres of Phillips Brook, a tributary in Leavitt Bay, and an inlet in Broad Bay. New milfoil infestation has been detected in Pickerel Cove and the weed has been spreading from Phillips Brook into Leavitt Bay. Smagula discussed chemical and nonchemical treatments, and spent much of the time fielding board members’ and residents’ questions about the safety and effectiveness of the herbicide, 2,4-D. Select board chair Kathleen Maloney inquired about the safety of this herbicide.
“When all the plants are dying what’s going got happen with the fish? How far is the herbicide going to spread? How will it affect water quality?” she asked.
Smagula replied that 2,4-D has been used since the 1920s in agricultural settings and on crops around the world; it has been used in aquatic systems since the 1940s, and in New Hampshire since the 1060s. She said the herbicide has been extensively studied.
“Two-four-D and 10 other (herbicides) were reviewed by the U.S. Army Corps of Engineers Environmental Research Center and of those, 11 total, 2,4-D was proven to be the most effective on milfoil, the most selective to milfoil, with no impact to non-target species. 2,4-D doesn’t migrate to groundwater. It binds quickly to sediment and doesn’t really move through the soil to the wells,” said Smagula.
She said the state conducted a study on lower Sunset Lake in Barnstead, which has very sandy subsoil. The state tested a well very close – about 10 feet – to the herbicide application area.
“We pumped that well routinely and that well did not draw the herbicide in even though the herbicide was applied adjacent to where the well was. So we no longer have that concern,” said Smagula.
She added that other New England states have conducted studies with satisfactory results. Another problem with milfoil is that fragments can float or be blown from one part of a lake to another, or can spread when weeds hitch a ride on the bottom of uninspected boats.
Select board member Harry Merrow questioned nonchemical treatments, such as hand pulling and barriers that seemed to have worked well in other areas. Smagula said barriers work well in small areas with limited water flows; but in sections of the lake where there is significant flow and shifts in water levels, barriers can be pulled out. She said barriers are most effective in areas no larger than 10 by 20 feet.
Another problem is that even though the barriers are netted and weighted down to just above the bottom of the lake, gases released by the vegetation come up and cause the barriers to billow. This billowing creates a navigational and swim hazard. She noted as well that the state is working with towns and community groups such as the Ossipee Lake Alliance on ways to control the spread of milfoil.
Some control work is planned for Danforth Bay in 2010. She said the state might take further action to restrict movement of the weed, such as apply netting to contain fragments. One other issue for Ossipee Lake is that it is a very large, interconnected lake system.
“The potential for milfoil spread is still there, and so action is definitely recommended in terms of containment and control,” she added
The following editorial by Larissa Mulkern also appeared in the November 19th issue of the Independent.
Kudos for an excellent presentation
We’ve hung around enough town halls to know that “the State” gets bashed around a lot by some elected officials and residents who complain about mandates, over-regulation, funding or lack thereof, and so on and so forth. The state Department of Environmental Services is often the target of scorn for – gasp! – imposing regulations designed to protect our water bodies, the environment, wildlife habitat, from pollution and over-development.
We were reminded earlier this week of the value of the services this agency provides, however. On Monday, Ossipee Selectmen, conservation commission members, and residents of towns bordering Ossipee Lake were treated to a fascinating presentation by NH DES Limnologist Amy Smagula, the exotic species program coordinator.
She spoke at length – and in plain English – about the problems with invasive milfoil control in the Ossipee Lake system, which includes infestations of the ugly choking weed in Danforth Pond, Broad Bay, Pickerel Cove and Leavitt Bay. Ossipee select board members expressed their concern with the use of the herbicide, 2,4-D, which is applied in pellet form in waterbodies with milfoil infestation.
Is this herbicide safe? Is it effective? Will it affect drinking water or public health? Will scientists learn down the road that 2,4-D is harmful after all? Valid questions, for sure, and the impressive thing was that Smagula was able to address all of these concerns with straight answers based on real data.
She explained the history of use, and all the scientific data that shows 2,4-d is safe for humans, fish and native plants as it targets the milfoil specifically. The “no swim zone” guideline after application has actually been reduced after studies show the herbicide dissipates quickly.
Smagula showed grace under pressure – it’s not easy standing up in front of skeptical board members and residents. She deserves credit for her poised and informative presentation.
We came away from the session with a much deeper knowledge and understanding of the milfoil problems and solutions. And in the event the select board does indeed propose a warrant article to set aside additional funding to combat the invasive species to protect a very valuable natural resource – our lakes – we hope that citizens support the effort. The combination of herbicide and non-chemical treatments and prevention is the way to go, and it won’t be free.