Vernon Town Council Approves Spending For Herbicide

By JOSEPH A. O'BRIEN JR.

Special to The Courant
April 21, 2010

The town council has approved spending $16,625 on herbicides to battle the invasive plants that have taken hold in Valley Falls Pond and Walker's Reservoir.

Members of the conservation commission agreed in March to follow the recommendation of George W. Knoecklein of Northeast Aquatic Research in Mansfield, who urged the town take action against the variable-leaf milfoil that's thriving in Valley Falls Pond and the milfoil and fanwort that have infested Walker's Reservoir East.

"These plants," the commission wrote in a memorandum to Mayor Jason L McCoy, "if left unchecked, can potentially degrade natural habitat and disrupt or eliminate native plant and animal species, including the wild trout population, in the Tankerhoosen River, in Tankerhoosen, Dobsonville and Talcottville ponds and potentially in the Hockanum River."

The town council this week voted to spend $3,350 to treat Valley Falls Pond and $13,275 to treat Walker's Reservoir East.

The town has applied to the state Department of Environmental Protection for the necessary permits to apply the herbicides. Public notices will have to be published and signs posted at both locations informing people about the intended pesticide use.

The commissioners had considered other eradication methods but concluded that the herbicides would likely be the most effective one.

Mechanical harvesting would make the problem worse because both species spread and propagate through fragmentation that would occur during harvesting. Also, harvesting is good for only one growing season. Officials considered introducing sterile grass carp to dine on the invading plants but were concerned that these fish would get into the river ecosystem and raise havoc with the trout.

Suction harvesting, in which a diver uses an underwater, venturi vacuum to remove the plants, was deemed too slow and too expensive. Vacuuming the 6 acres of Walker Reservoir would probably take 12 weeks and cost about $108,000.

The commissioners acknowledged that there would probably be concerns about the herbicides' effect on the environment and "that citizens may question their use." The herbicides "can be expected to eliminate fanwort and milfoil from the ponds for a period of three to five years," the commission said.

The commissioners also urged that the town develop a long-term, comprehensive management plan to control invasive species. "We specifically recommend that in the intervening years before these plants return to their present density, the town consider planning and budgeting for the future use of suction harvesting, which we understand may become more cost-effective."