We have received permission to use the herbicide triclopyr to treat the Eurasian milfoil in Lake Fairlee. Although we will be treating only about 30 acres, less than 7% of the lake, for safety we are required to close the whole lake for two days. Notices have been mailed to owners of lakeshore properties, and signs (above) will be erected around the lake to prevent accidental use.
The herbicide we will be using is toxic to certain plants, and particularly hard on the milfoil we want to get rid of. HERE is how it works. On the other hand, it is relatively benign in animals, which makes it a good choice for use in our lake. Before the first lake treatment in 2010 I pulled together this collection of articles [LINK] to help evaluate any risk of its use. Lake water may not be used for irrigation for four months – or until the concentration of triclopyr is below 10 parts per billion. If you are accustomed to watering your lawn with lake water, please make other arrangements.
Vermont is among the most restrictive states, imposing strict regulations on the use of any chemicals. Even so you can see on the sign above that fishing, swimming, and washing in the lake are permitted after the second day. According to their regulation one could drink from the lake (which we do not ever recommend, for a variety of other reasons) once the concentration of triclopyr falls below 75 ppb, which took less than four weeks in 2010.
So please forgive the inconvenience. We have scheduled the treatment as early as we could, so as to minimize conflicts. Bear with us and get ready to enjoy another glorious summer in a (more nearly) milfoil free lake.