DEC Details Standards For Herbicide Permits

Fishermen enjoy recreation on Chautauqua Lake near Lakewood Beach during the time SOLitude Lake Management began treating waters with herbicides Aquathol K and Navigate last month. P-J photo by Eric Zavinski

Herbicides Aquathol K and Navigate were used by SOLitude Lake Management to treat about 400 acres of Chautauqua Lake last month, and the New York State Department of Environmental Conservation revealed more of its thought process on permitting areas that have been treated.

On behalf of DEC media relations, Maureen Wren told The Post-Journal that multiple divisions of the department are involved in a “comprehensive decision-making process” for the permit applications.

Wren listed consideration for public health and preservation of the lake’s natural resources as the two major reasons to restrict where herbicides were allowed to be used this year and in previous years’ applications.

“The particular herbicides chosen for the treatment are not expected to have a significant adverse impact to native vegetation,” Wren explained. “The timing of the pesticide treatments allows these herbicides to selectively target invasive species.”

Navigate was used to target Eurasian watermilfoil, and Aquathol K was used to target curly-leaf pondweed. Both nuisance plants are considered invasive species, and some stakeholders were concerned that the herbicides would potentially kill native aquatic plants.

“DEC staff observations of aquatic vegetation in Chautauqua Lake following herbicide treatment in the years 2017 and 2018,” Wren said, “showed little impact to non-target vegetation from ‘drift,’ allowing continued growth of desirable native vegetation in those same areas following the herbicide treatment.”

She said that concentrations, formulations, dosages, locations, treatment plans and application rates for the herbicides were designed to remove invasive species from the lack without heavily impacting lake wildlife.

“The chosen herbicides have low to no toxicity to fish and mammals, including bats that may drink lake water,” Wren said.

According to the DEC’s Ecotoxicant Research Unit, neither Navigate and Aquathol K were found to have toxic effects on the spiny softshell turtle, an endangered species native to Chautauqua Lake.

Surveys indicated fish spawning and nursery areas, in which herbicides were not applied. For fish that rely on invasive weed species in part for habitat, they are expected to adapt to native weeds that are expected to replace watermilfoil and pondweed, Wren said.

Drinking water setbacks for areas treated with Aquathol K were greater than or equal to 600 feet, and the setback distance for areas treated with Navigate was greater than or equal to 1,200 feet.

“The closest proposed herbicide treatment area is approximately 15,000 feet away from the water intake for the Chautauqua Institution,” Wren said. “A restriction on drinking water (had) been set at 50 parts per billion for both pesticides, and appropriate testing will be conducted to protect drinking water resources.”

Treated areas in the waters of the towns of North Harmony, Ellicott and Ellery and villages of Lakewood and Celoron were shallow littoral zones in water up to 6 feet in depth. Areas and channels were selected to enhance boat navigation as well, and a channel leading into the Chadakoin River was also treated for that reason.

Wren said Environmental Conservation Law, DEC pesticide policy and the Chautauqua Lake Macrophyte Management Strategy were used as guiding documents for setting up permitted treatment zones. Other than North Harmony’s permitted zones, all permitted areas were 100% treated with Navigate and Aquathol K last month.

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