Paradox Lake to become latest to be treated with milfoil herbicide

Adirondack Park Agency approves permit for 3rd Adirondack lake to use ProcellaCOR

By Zachary Matson

Use of an aquatic herbicide to kill one of the region’s most invasive plants continued to gain momentum Thursday.

The Adirondack Park Agency approved a permit for the Paradox Lake Association to use ProcellaCOR EC in 2024 or 2025 in Paradox Lake. APA board members also highlighted growing interest in applying the chemical from communities across the park and suggested exploring more coordinated strategies.

The Paradox Lake approval follows use of ProcellaCOR EC on Minerva Lake in 2020 and Lake Luzerne this summer.

Officials said the herbicide rid both lakes of large populations of Eurasian watermilfoil, which threatens recreational uses and ecosystem health throughout the Adirondacks. A plan to use the herbicide on Lake George is tied up in court after its approval was challenged by the Lake George Association. 

“There is a growing track record for the use of ProcellaCOR nationally, regionally and locally,” said Aaron Ziemann, an APA staffer overseeing the permit application.  

RELATED READING: What is ProcellaCOR herbicide and how does it work?

The Paradox Lake permit allows for two applications of the herbicide in the 60-acre lake along state Route 74 north of Pharaoh Lake Wilderness in the Town of Schroon.

The lake association plans to deploy around 13 gallons of the herbicide near the lake’s eastern inlet and another 11 gallons in a narrow stretch of water between the eastern and western basins – areas of the highest density of the invasive plants. 

Eurasian milfoil was first spotted on the lake near a boat launch in 2008. Since then the lake association has supported hand harvesting of the plant with volunteers and contractors, spending $190,000 on the work over the past three years. Despite those efforts, invasive milfoil has continued to spread and multiply in recent years. 

The permit expanded water sampling requirements compared to previous permits as APA staff aims to gather more data about potential impacts in parts of the lake light cannot reach. The herbicide also impacts waterlily and a smattering of other native plants, but those plants are expected to recover after a quick die off of invasive milfoil. The permit requires follow-up monitoring as the herbicide dissipates in the water column and a plant survey later in the season.

The herbicide mimics a growth hormone, causing rapid and uncontrolled growth that kills the plants within days. Herbicide users in other lakes have reported nearly complete removal of the invasive plants and only sporadic return following growing seasons. Ziemann said treatment at Minerva Lake has resulted in a “suite of native plants redefining the space” in subsequent years. 

The town of Lake Luzerne pursued APA approval in May amid the ongoing litigation over Lake George. The board approved that request, and the community applied the herbicide May 30.

Jim Niles, a Lake Luzerne town board member, said a visual survey conducted the day before and 30 days after the herbicide use showed impressive results. 

“It really showed exactly what was predicted,” Niles said in a recent interview.

The Lake George Association raised concerns that there were still too many uncertainties about how the herbicide would respond to that lake’s circulation patterns and impact native insects, plankton and plants. The Adirondack Council and Protect the Adirondacks, two parkwide advocacy groups, have also urged caution, and both organizations opposed the Paradox Lake permit.

Dave Wick, executive director of the Lake George Park Commission, attended the agency meeting. In an interview after the Paradox presentation, Wick said park commission and Lake George Association leaders planned next month to discuss herbicide plans for Lake George outside the confines of the ongoing litigation, now under appeal. 

Wick said he plans to target next year for application. “The hope is still 2024, it’s the right thing to do,” he said. “It’s really difficult to see what concerns are left after you hear a third-party, unbiased presentation.”

During the meeting Thursday, board members predicted a surge in requests to use the herbicide from around the park. They discussed the need to expand the scientific study of the herbicide’s use and assist communities attempting to manage widespread milfoil infestations. 

“We are all dealing with the same issue, so why can’t we come together to think through a solution?” board member Zoe Smith said. 

Board members also learned some Paradox Lake trivia: When spring flows rise high enough on the Schroon River, the water in the lake’s outlet can reverse and head back into the lake.

“It’s a paradox,” Ziemann said. 

Gwendolyn Craig contributed to this report. Photo at top: Paradox Lake as seen from atop Severance Mountain in Hoffman Notch Wilderness. Photo by Zachary Matson

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