Herbicide in the Hudson? Officials look to eradicate invasive species with drones

On a frigid winter afternoon like today, it is easy to dream of warm summer days spent kayaking on the Hudson. It is also easy to remember the struggle of cutting through thick swaths of water chestnuts near the river’s shore to reach open waters.

Water chestnuts, Trapa natans, an invasive aquatic species released inadvertently into waters of the Northeast in the late 1800s, continue to take over sections of the Hudson River. In Germantown, officials are looking to eradicate 156 acres of invasive water chestnuts that blocks off nearly two miles of waterfront and stretches 1,000 feet into the Hudson River.

Despite efforts to cut the water chestnut’s long tangle of roots under the water’s surface using a special cutter rig constructed by the town historian, access to the river continues to be matted with this invasive species. “This water chestnut blockade dates to about 2010 and has gotten steadily worse every year.”

Last week, the New York State Department of Environmental Conservation approached the Town of Germantown to discuss potential for a pilot program to help remove 156 acres of invasive water chestnuts using a herbicide.

According to the town’s waterfront committee:

This proposed pilot would include the use of an herbicide which is no one’s first choice but maybe one of the only viable options in our case. The proposal is to do a targeted, foliar (on the leaves only) application of a chemical called Imazamox. This would be done by drone (for minimal water disturbance) with a licensed pilot trained in wind and tide considerations on site. Once the chemical has dried on the leaves in a few hours, little is said to wash into the water. This chemical is considered to have low impact to marine life and can be used around drinking water intakes which we consider important even in a very diluted form for our downstream neighbors in the Hudson 7. This chemical renders the plants unable to grow or produce seeds which may not always be achieved with our current chopping methods. The DEC would monitor for oxygen levels as the plants decompose as well as water testing daily for residual chemical.

The pilot program also includes “extensive native habitat restoration efforts the likes of which Germantown would not able to do on its own.” Native plant samples would be propagated by the Cary Institute in Millbrook and planted yearly until the water chestnuts have died off.

The proposal will be discussed at the Germantown Waterfront Advisory Committee meeting on Monday, January 6, 2025 at 7pm, as well as the Town Board meeting on Tuesday, January 14, 2025 at 7pm. Both meetings are open to the public and Zoom links can be found on the town website meeting section: https://germantownny.org/

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