 BELGRADE -- Using an herbicide to eliminate the spreading Eurasian water milfoil on Salmon Lake is not the best option -- but it may well be the only option left that stands a chance of actually working, officials and some advocates say.
"We can't have one plant survive," McGrath Pond Salmon Lake Association president Rick Swanson said at a meeting hosted Wednesday by the state Department of Environmental Protection. "If this gets into Great Pond, the party's over."
The DEP is considering using herbicide in Kozy Cove near the Salmon Lake outlet to control the spread of Eurasian milfoil, a highly aggressive aquatic plant that can form dense mats and congest waterways.
"If Eurasian milfoil is left unchecked, it is capable of displacing native plants and altering the lake's habitat," DEP environmental specialist Paul Gregory said. "Given the situation (at Salmon Lake), we feel appropriate use of herbicide will provide the most effective means available to prevent its spread and allow us better opportunity to control this infestation manually."
Milfoil spreads readily by fragments that float downstream or that are transferred by animals, boats and trailers.
Maine has been virtually untouched -- the only other known Eurasian milfoil infestation in Maine was in a small, private pond in Scarborough. A different variety -- variable leaf milfoil, a similar invasive plant species -- is prevalent and spreading in Messalonskee Lake.
Eurasian milfoil was discovered in Salmon Lake by a summer visitor last August.
DEP divers began removing plants within a week and conducted a total of four dives into September, said John McPhedran, invasive aquatic plants specialist for the DEP.
Divers have removed 325 plants, more than twice what was removed last year, during five dives since May of this year.
Control efforts have also included restricting boat access to only residents along the Kozy Cove shore, placing mats on the cove bottom to restrict sunlight to the plants and installing nets at the cove's mouth and outlet to capture floating plant fragments.
"We're finding more plants on each dive," McPhedran said. "As a staff, we feel we need to apply herbicide to the cove in order to achieve our goal, to prevent the plant from spreading. We're not going to get it with mechanical control."
The applications can only begin with a permit from the DEP's Division of Water Quality Management, McPhedran said. The application should be completed within two weeks and the water quality division must make a decision within two weeks of receipt.
The permit, if approved, can be appealed for 30 days -- but treatments can begin immediately. Gregory hopes treatment will begin by the middle of August. But officials are hesitant to say just how effective the herbicide will be.
"We don't use the 'eradication' word," McPhedran said. "Eradication is very difficult to achieve."
The herbicide may suppress the plants enough to allow it to be controlled through diving and other "mechanical" methods, Gregory said. "Right now, we've lost that advantage," he said.
While residents expressed concern about the herbicide's unintended consequences on other plants, animals and people, there was no vocal dissent.
"We wanted to avoid pesticides if it was possible to do so," Swanson said. "We had to make a good-faith effort. If we don't want to be doing this 10 years from now, we need to turn up the heat."
BY CRAIG CROSBY
Staff Writer Kennebec Journal & Morning Sentinel 07/23/2009 |