Lake Iroquois Milfoil Treatment Unlikely This Year

An herbicide treatment of Lake Iroquois in Chittenden County, Vermont, isn’t likely to occur this year because the state received so many public comments that it will not have time to respond before the window has passed in which the first treatment must occur.

Although representatives from the state say the herbicide won’t unduly harm species other than milfoil, critics of the practice say it does harm fish, even if it works as intended.

Some of the best fishing in a lake or pond occurs at the border between milfoil and open water, said Shawn Good, a fisheries scientist with the Vermont Fish and Wildlife Department. That’s because big fish prey on juvenile fish that live within the milfoil, he said, and juvenile fish live in milfoil because it offers nutrients and protection and the other qualities that define a good fish habitat, he said.

A lake with a milfoil infestation and more than half its area free of the invasive plant still serves as a functional ecosystem. Such a lake provides much better habitat for fish than the same lake following an herbicide treatment, when the milfoil that once provided living quarters for small fish lies rotting on the bottom of the lake.

Fish can’t distinguish between native species and invasive milfoil, Good said, and they flourish in milfoil just as readily as in any other dense aquatic foliage.

When lake associations like the Lake Iroquois Association apply lake-wide herbicide, it kills off all the milfoil, leaving the fish without their accustomed habitat.

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