Group questions herbicide plan for Adirondack lake (update)

ALBANY – An environmental group called on a state agency today to hold a formal public hearing before deciding whether an Adirondack town can use a chemical herbicide to kill aquatic weeds that have formed choking masses in a popular lake despite intensive efforts to control it with divers hand-picking plants and smothering them with plastic mats.

The Adirondack Council wants the Adirondack Park Agency to hold a hearing on the Warren County town of Chester’s request to use the chemical triclopyr, with the trade name Renovate. It would be used to kill Eurasian watermilfoil in Loon Lake. The agency is scheduled to consider the permit request at its monthly meeting on Thursday. Its staff has recommended approval of the plan, which was subjected to a public comment period.

The Adirondack Council argues in a statement released today that the chemical would harm other plants, including a threatened species, and has killed large numbers of snails in another Adirondack lake, Lake Luzerne.

“The APA should not grant another permit to use chemical herbicides in any Adirondack lake until it figures out what went wrong at Lake Luzerne in 2011,” Diane Fish, Adirondack Council’s acting executive director, said in a prepared statement. “This chemical killed alarming numbers of snails and suppressed dissolved oxygen to dangerous levels, putting other organisms at risk.”

Fish said chemical herbicides “should be used only as a last resort, when all other methods have failed.”

Eurasian watermilfoil is a highly invasive aquatic plant that can form dense mats in lakes, choking out other vegetation and making swimming and boating difficult. Several chemical herbicides have been used to control it in many lakes, but environmental groups have strongly opposed using herbicides in the 6-million-acre Adirondack Park. In Adirondack lakes infested with Eurasian watermilfoil, control efforts are typically limited to hand-pulling by paid or volunteer divers

Fred Monroe, town supervisor of Chester, said the town, with a population of 3,500, has been using volunteer divers for several years to pull watermilfoil in Loon Lake, a popular summer vacation destination ringed with camps and cottages. Despite the efforts, the weed kept spreading, so the town hired professional divers to help harvest the plants and spread plastic mats to smother them. Last year, 60,000 plants were harvested, he said.

But there’s one 15-acre bay in the 500-acre lake where the weeds are too thick to control through harvesting or mats, Monroe said. A consulting firm, Lycott Environmental, advised the use of Renovate, saying it has been used successfully throughout the Northeast and is very selective at targeting watermilfoil while not harming other plants or animals.

The plan is to use a curtain barrier to confine treatment to the area of dense growth. One homeowner who has a drinking water intake near the treatment area has agreed to shut it off and use bottled water provided by the town during the treatment, Monroe said.

The town’s attorney argued in a letter to APA last week that grounds for holding a formal hearing hadn’t been met, and that it’s critical to do the treatment this year to prevent rapid, uncontrolled spread of the vegetation.