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You can rip them out, poison them, vacuum them up, or smother them with sheets of plastic, but your chances of eradicating the exotic plants that are invading the region’s ponds and lakes are slim, according to environmental officials.
“Once they are in your lake, you are very unlikely to get rid of them,” said Anne Carroll, director of the Office of Water Resources in the Massachusetts Department of Conservation and Recreation. “You just have to deal with them — like mowing your lawn.”
Lake Cochituate is battling milfoil. Whitehall Reservoir in Hopkinton is covered with fanwort and milfoil. And parts of the Charles River lakes district from Waltham to Newton are so choked with water chestnut that you can barely see the fanwort weeds underneath.