SOUTHWICK – The annual treatment of Congamond Lakes for invasive plants is set for Tuesday, May 19.
The town has contracted with Aquatic Control Technology (ACT) once again for the chemical treatment aimed at reducing and eliminating invasive plants, Eurasian milfoil and Curlyleaf pondweed in particular.
Michael Lennon, a biologist with ACT, reported that “invasive plant cover continues to decline” on the lakes but recommended treating about 15 acres of the lakes now and suggested the town budget for treatment of an additional five acres along the western shore of Middle Pond “in the event that more growth develops before treatment.”
Lennon found milfoil in Turtle Cove, which he said was expected, and curlyleaf pondweed was found in limited areas where it has historically been an issue.
Residents are warned that using the water for cooking and drinking is prohibited until May 21, swimming is prohibited until May 20, watering livestock is prohibited until May 20, and irrigation is prohibited until May 22.
“It will probably be too cold for swimming and people don’t normally use it for drinking or cooking. There’s no livestock right there, so irrigation is really the main thing people have to be aware of,” said Lake Management Director Richard Grannells.
The lakes have historically been treated with a selectively targeted herbicide called Diquat.
Eurasian watermilfoil is a non-native invasive plant. It has feathery underwater foliage and was once commonly sold as an aquarium plant. Eurasian watermilfoil originates from Europe and Asia, but was introduced to North America many years ago and is now found over much of the United States.
Grannells said the plant is widely distributed and difficult to control.
The sheer mass of plants can cause flooding and the stagnant mats can create good habitat for mosquitoes. The mats can rob oxygen from the water by preventing the wind from mixing the oxygenated surface waters to deeper water. The dense mats of vegetation can also increase the sedimentation rate by trapping sediments.
Grannells said people couldn’t swim or boat in it.
“It grows so rapidly it can go unchecked,” he said. “It can grow from the bottom of the lake to the top surface and form a tent on the water. It can take over other good plants and kill fish.”
Grannells said Eurasian watermilfoil also generates its own fertilizer, which aids to its rapid growth. It can also grow from cuttings, so if a boat runs through it and cuts it, the leaves can start a new plant.
